My excellent adventure through some battery builds

Batteries, Chargers, and Battery Management Systems.
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ElectricGod
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 19, 2016 3:42 pm

Okami wrote:Ok - so I got a quick reply for you, perhaps you will get the chance to reply soon!

A very clever way to measure the cells! Indeed. I think you have changed my understanding now on how to check cells for high load use..

Ok, some conclusions I got when I tried to discharge my Panasonic CGR-CG pack 4s2P pack (~16v, ~2250mah per cell, when new and 2-3c discharge - datasheet data)

I got to about 3.1 -3.2 volts under load per cell (~25w) and the cells became considerably weaker, if they were pulling the mentioned 25w of load before, then now they pulled only 21-22w of power)

When I disconnected the load.. the charge went up to even 13.43v
I forgot to monitor the total voltage when under load but it was around 12v..

Anyways - I concluded that the performance is quite bad when the cell is below 3.3 under load.. (same conclusions can be found on the net, of course)
And the load voltage is about 3.5v when the cell should be stopped discharging probably

The capacity I managed to sqeeze is out was about 2.650 mah, out of 60-70% full pack when I started monitoring the discharge.

---

So - anyways when I connected to the balance charger, the different between highest and lowest cell was about 0.08v I believe, so almost 0.1v (~3.44 and 3.36)

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@ElectricGod, though, Im writing all of this to ask you - so what exactly happens when you have different capacity parallel groups? This was the thing why I wanted to test each cell, so that I can arrange them in a manner, the capacity levels are somewhat equal..

How will the pack act when one group has 2ah, another one has 1.8ah and the last one, for example, 2.2ah..

--

I actually wanted to make new topic about mixing high discharge cells with low discharge cells (like laptop batteries).. and what would be the effects of doing so, it looks like there are ppl who have even mixed lipo and li-ion, li-ion and lifepo, and even Pb and lifepo.

So yes, another thing im looking for is, what I should be beware of besides monitoring the cell voltage when connecting two different packs in parallel (same voltage of course but perhaps a little weaker capacity). I do believe that the weaker pack will probably drain faster and will have to be disconnected, while the bigger one will probably have more juise and otherwise.. just supplement the weaker pack, when it has reached its low point.
I run mixed. I have the battery box over the back wheel and then the battery bay under my feet. The battery bay has LIPO cells in it and the box is full of used LION laptop cells. I have in the past run both sets of batteries without a BMS on either one of them. IMHO LIPO will drift out of balance more quickly than will LION so it always made me nervous to not have a BMS on my LIPOs, but never the less I ran for a couple of months with no BMS on them. I was just way more hawkish about checking them every other charge. The LION cells went 2 months between checking if they were still in balance or not and they were fine. By then I had purchased a couple of BMS and didn't worry about it anymore. I still run mixed, bu there is a single BMS for the LIPO packs and another for the LION packs. LIPO is cheap and wont last very long. LION is definitely the better technology and will last for years..even laptop cells. I use a LION BMS on my LIPO pack. LIPO charges like LION except the end voltage is 4.2 rather than 4.1 volts. My charger is set to 82 volts or 4.1 volts per cell at 20S. As a result the LIPOs charge to 4.1 volts for a very small loss in capacity, but longer life span.

LIFE charges very differently from LION and LIPO so as long as I had a LIFE BMS on those batteries, then I wouldn't be afraid to run mixed with them as well.

In my configuration I have LIPO and LION. Pretty much any cell type you get...including alkaline and SLA batteries, they get saggy towards the end of their charge. I expect that as I am nearing the bottom of my charge that acceleration is going to be weaker than normal and that if I do crank the throttle that I am going to sag sufficently to cause the BMS cut-off to happen or the protection voltage level of my controller to stop me..and they do. I also have noticed many times three behaviours. The first is that close to low battery charge that under load, the batteries sag quite a bit. Lets say I am running at 65 volts or 3.25 volts per cell at 20S. I have to hit the throttle slowly and gradually or I will drop below 60 volts very quickly and then bounce back up to 65 volts again. That's a decent amount of sagging! The second thing is I use regen...who wouldn't...so just coasting if battery voltage under load was 65 volts, now it jumps up to like 72-75 volts. Then coming to stop...or no load and no regen, battery voltage settle to like 68 volts. I never look at my resting voltage as true battery voltage. In fact I call this the "recovery voltage". Any partly discharged battery if you let it sit for a little while will slowly increase in voltage as electrons slowly migrate towards the negative pole. It's not magic happening, the battery has exactly the same charge it had before, just the electrons are a little bit more available for a second or 2 and then the battery returns to whatever it's charge state was before. The only battery voltage I care about is the one I read when I am loading the batteries. All the rest are momentary numbers.

All my LION packs are in parallel at a cell level so they can run on a single BMS. I have 6 20S2P battery holders, each with four 5S balance cables. The balance cables are all connected in parallel. So starting from the negative most end of each pack, that's connector 1 to the positive end of the pack where connector 4 is. All the connector 1 cables are connected together. All the twos are connected together and so on. Electrically it's the same thing as welding up a pack with 12 cells in parallel by 20 cells long. The stronger cells and the weaker cells can't discharge at different rates. Being that all 12 cells are connected together in parallel, they act as a single cell...a single cell that is the aggregate of all 12 cells. IE: it doesn't matter that there is a weak cell or not, it can't discharge faster than the rest of the cells it is in parallel with. This is precisely why when I do load testing I only do 2P at most. One or both of those two cells in parallel are weak on a channel that discharges too quickly, but I won't know which cell until I try both of them individually. Most of the cells I harvest that actually charge to 4.1 volts are good for 1800mah at least. It's not dead set to be true all the time, but most of the time it is. Don't ask me why that is, but it seems about 80% reliable. Cells that won't fully charge typically wont get close to 1800mah. A fair percentage of cells charge to 4.1 volts, but are less than 1800mah so I can't depend on fully charging as proof of a good enough cell...just that if a cell doesn't fully charge,that it's already a throw away. Assuming I get the Ah for the entire pack that I am looking for (4000mah) and the cell voltages for each channel are above 3 volts when I get to 4000mah, then it's safe to assume that all the cells used in that load test are at least good enough or 2000mah. I usually load test until the RC battery monitors start alarming. It's quite possible to measure more than 4000mah as a result. It is possible to get a strong cell in parallel with a weak cell and as a result a weak cell slips through if I stop at 4000mah. By going until the monitors alarm, that usually means a channel or 2 has dropped faster than the rest of the channels. Those cells on that channel or channels contain one or more weak cells and need further testing. The rest of the cells in the other channels...assuming I have reached 4000mah are all good enough. It has happened many times that I don't get to 4000mah before alarms start going off. I keep a stack of charged up, but weak cells on hand that are marked as weak. When a channel dips too quickly, I pop out the cells in that channel and pop in charged cells in their place and then let the load test continue. The result is the rest of the 40 cells continue their load test where they left off.

Hi and low discharge cells used simultaneously...
Since all the battery packs are electrically the same being they are in parallel, the same load that goes to a 1C cell goes to a 5C cell and a 100C cell. In my LION pack I have a string of 40 18650PF cells. If I remember correctly, they are good for 5C. They are electrically cell per cell in parallel with the laptop cells so no one cell can discharge more quickly than another. If the 18650PF measures 3.9 volts, the other 11 laptop cells are going to measure 3.9 volts as well...even if I disconnect everything and measure them separately. AS far as mixed capacities is concerned between different packs...I have a 20C 20S2P 20,000mah LIPO pack in parallel with a hodge podge of laptop cells that all meet the "good enough" criteria. Since the load can't choose which battery source to pull current from because the LION and LIPO packs are in parallel, whatever load there is gets spread evenly among all the battery sources there are. If I'm pulling 50 amps...more or less each cell sees 1/14th of that 50 amps or 3.57 amps each. Fortunately, the laptop cells are just fine with that load. and at most I pull 60 amps. However, there is another factor that plays into things. IR is the internal resistance of the cell. Cells with low IR are going to see more current loading than cells with higher IR. That's just basic ohms law. Lets pretend my LIPO pack has a 1 ohm IR for the entire pack and the LION pack has a 2 ohm IR for the entire pack. That effectively means the LIPO pack is going to see 2X the current load that the LION pack is seeing. By the way, my LIPO IR is a tad lower than the LION IR, but not 50% lower. The result is the LIPOs will run down first and then their BMS shuts them off. I definitely notice when this happens, but the IR's for both pack types is close enough that it's just a minute or two that I'm running LION only and battery voltage is so low anyway, that I'm better off walking.

My LIPO pack is on a seperate BMS from the LION pack. The LION pack is good for 24,000mah. The LIPO pack is good for 20,000mah. 4000mah is hardly anything in the grander scheme of things so my packs despite being differing chemistries are pretty close to the same capacity. If I was running without a BMS on each pack type, it would be problematic to run down the packs to 60 volts because the LIPO pack would get to 3 volts per cell and continue to discharge while the LION cells were still 3.2-3.3 volts per cell. This would be bad for the LIPO pack.

Don't let the mega and giga watters on ES talk you out of using laptop cells. They aren't necessarily wrong. Expensive and high discharge rate cells are better. you probably bought them new so you are getting the best capacity they have to offer. This is all true. However, sufficient numbers of 18650 31Q cells to run my scooter would cost me about $1400 while my scrounged laptop cells cost me nothing but the expense of finding the good ones and making battery holders and a few other misc items...or about $250. Depending on your economics and budget, which one is better is a matter of perspective. Me personally, I have access to used laptop battery packs and I can make battery holders easily so my economics say use the free cells.
ElectricGod...it's a joke...don't take things so seriously folks!

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Okami
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Re: My excellent adventure through some battery builds

Post by Okami » Dec 21, 2016 7:00 am

Cool, lots of more info to process now.. :)

I tested the cell pack I got - the 4S2P one and it showed that 3650mah were pumpet into the pack, so about 1800mah per cell, just as I ''predicted'' as I also foolishly bought these 2 packs (I got 2 of them) from ebay for about 2 eur per battery, (16batteries and ~35eur cost).

Too bad I did not know about nkon eu site back then but okay from nkon the shipping cost would be 11 eur itself, so I would probably get ~10 batteries but they would be new at least.. not 1-2yr used in medical devices..

------

So yeah, that's the price I payed for jumping into li-ion battery tech too early.. I had about 6-10 batteries laying around, and 6 of them were panasonic CG variety, so I thought not to have mixed brand batteries I should go with the same brand and there was a listing for such 'medical' use batteries. If there were not a word medical, I probably would not have bought them.. It is just the pure coincidence that a few days earlier or a week earlier I saw someone mentioning (perhaps on battery university) that in medical field the li-ion batteries are tossed away way before their time, as they replace the batteries on a timely basis not the actual capacity or such.. as devices which rely on them cannot stop at all costs so the risk of a battery stopping is too great and they replace the batteries once they have reached their deadline..

So yeah, instead of 2250mah for new batteries I got 1800 mah per battery just as I speculated (around 300 cycles used or so)
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Okay, so that's the end of side story on how I got tossed into choosing li-ion, as initially I thought about going with lipo's but I disliked the risk of fire (considering lipo safe bag) and also the short lifespan of them..

Anyways, so now Im gonna combine laptop grade - low discharge cells with high discharge ones, and check how well they perform!

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From what you @ElectricGod told me, I can conlude that I should expect one pack to be drained faster.. and that's all. As of now I will probably have laptop grade pack with less capacity, so I speculate that it will be drained faster than the high discharge pack.

I will probably try to make some more tests to see at what discharge rate the cells start to get hot, so that I would know how much can I drain them.. Will also fit lipo alarms on these packs but what I dont like is that these cheap lipo alarms dont show very precise cell voltages and usually there is quite a big drift in accuracy they show.. perhaps I just got a bad ones.. which dont show correct per group/cell voltage but still show good total voltage.

So probably should think about a bit better per cell/group voltage monitors, which does not start to beep annoying when one of the cell group's start to seemingly drift below the set voltage treshold..even if they are a few milivolts on top of it.

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On a side note - I actually wanted to tell that some ppl have placed regular digital termo-meters in their pack or close to motor.. of course you dont get the benefits like visual indicator our sound out of them.. but if you manage to mount these in your panel (if you have one), then it might be a cheap way to check temp's once and then..

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ElectricGod
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 21, 2016 9:16 pm

Medical cells...I would assume that since it's for medical purposes they probably use hi grade cells too. Although why they would use cells with high discharge rates doesn't seem likely. Just build the pack to handle the amperage of the machine plus a little extra and call it good. It's total Mah that would matter the most. IE: Being able to run for 24 hours on battery or whatever the standard is. I'll have to look into medical packs. They probably are in better condition than a typical laptop pack which gets tossed because the user is getting less than their expectations from battery run time. A medical pack is replaced based on a schedule rather than usability left. They probably get swapped out after a year at most and 90% of the time were not used since a hospital has generators. Pretty much the only times those batteries get used is the short stint between point A and point B when the device needs to be unplugged and then it gets plugged in again. If anything, the cells have seen lots of small charge cycles.

There's no such thing as "too early" when it comes to LION. How else are you going to learn other than to make a few mistakes along the way and of course to read what others did? Personally, I'm willing to make mistakes, try the oddball thing or just plain to find out for myself. When I started on this laptop battery thread, I was "borrowing" someone elses thread originally and so a lot of mega watters got on there and told me how making up battery holders and using laptop cells was a bad idea. I read what they wrote and considered their reasons and didn't necessarily disagree with them, but then I decided I didn't care and did what I thought would be a reasonably good idea anyway. At worst, I would be out some money and time. AND...I had already been harvesting laptop packs and been using the cells to power flashlights and other things for years. IMHO...it was a good idea...and that has proved to be the case. I got told how my battery packs would be unreliable crap multiple times and how real welded up EV grade cells would be so much better as to make my used laptop cells in battery holders virtually worthless. I realized quickly that with anything there are the pureists that won't compromise on anything and will gladly tell you how your idea is dumb. I also noticed that there were others like myself who thought that the compromises were not overwhelming and were willing to use an option that wasn't the ideal, perfect solution and to accept it's limitations.

LIPO vs LION vs LIFE...
Of these three chemistry types, LIPO is the most reactive and LIFE is the least reactive with LION somewhere in between. Tesla, medical and airplanes use LION...they can't be too reactive when 2 of the 3 are life or death dependent on LION. I basically said that to create a baseline. OK...on to LIPO. I used to be an avid RC flier and car driver. I've had some spectacular wrecks where parts go flying everywhere. 3D helis are notoriously good for self destructing on impact with just about anything that's not air. More importantly, protecting the LIPO pack is not possible since the platform needs to fly and be very nimble in the air. Weight is a huge concern so you eliminate things like protective boxes and cages around the battery pack. I have never had a LIPO pack catch fire from a wreck into a wall or in a heli crash...despite the RC car or heli essentially exploding into a zillion pieces. That says a lot for LIPO packs. They are pretty tough. Can you over charge or over discharge a LIPO pack? Sure you can and also run them harder than they can handle and make them get hot enough to have issues. I've run a few packs hard enough to make them bloat, but never hard enough to make them explode. With anything, use them withing their limits and they will be fine. This is why I've never had a LIPO pack burn up. whenever I see someone moan about how their LIPO pack burned up, all I can think is "What were you doing to that pack and why didn't you monitor it more closely?" A simple RC battery monitor on the balance connector will let you know cell voltages are low and most of them are programmable for the cell voltage. Set it to 3.5 volts so you can't get close to depleting the pack without knowing about it. Get a BMS!!! They are better than gold bricks when it comes to protecting a pack and they come in just about any cell count and amperage you can imagine for a reasonable price. Ebay has tons of low cost BMS that work well for EV purposes. I have BMS's on my rides, but not always. I've run without them before and you just need to be more aware of your pack status. It's not rocket science. As a result, LIPO is just fine and very safe. LIPO has a couple of advantages over LION. They have solder tabs so you can make up packs any way you want with nothing more than an iron and some solder. LIPO is cheaper than is LION. You will pay more for the same Mah of LION than you will for LIPO. LIPO has much higher discharge rates than LION. Show me a 120C 18650...they don't exist. Show me a 30C 18650...I don't think they exist either. 5-10C is about it. So for compact, high delivery storage, LIPO rules. I have some 30C nano quad copter batteries. They are 150mah and are about 1/2"x1/2"x1/4"...that's 4500mA out of a tiny LIPO battery. Show me a similarly sized LION cell that can do that! LIPO cells come in pretty much any capacity and size you can imagine. LION predominantly comes in the 18650 form factor and have capacities of 1300-3600mah. LIPO cells come in 10mA to 20,000mA...in a single cell. The possibilities of finding a LIPO solution that meets your needs in a single pack solution are probable...not so for 18650's. No EV out there runs on a 6S1P 18650 LION pack. LIPO has it's place...it wont have the recharge cycles of LION, but depending on what you are doing, it is very useful and if treated right can be very safe. And like any battery solution, LIPO gets better and better as new developments are made. I remember not so long ago when a huge LIPO pack was 5C and 5000mah and now you can get 20,000mah with 50C.

On the subject of doing dumb things with LIPO's...
Some time ago, I built a 12S LIPO pack, but didn't have a BMS for it yet. I had ridden for a week on it and just been careful to not get too deep into the pack. One night, I was distracted, didn't think about it and plugged in my EV charger. Normally that one pack, I would balance charge on my RC charger as two 6S packs. My EV charger output 56 volts. With BMS's on the other packs, this was not a problem as the BMS would stop pushing current into the batteries when they reached 4.2 volts per cell. This one pack with no BMS of course continued to slurp up current as long as there was more voltage to get to. 12S LIPO should stop at 50.4 volts. It had been several hours before I realized I forgot to manually charge that one pack. I was mad at myself to be sure, but was also concerned that I would have a serious situation on my hands. My watt meter read 56 volts. I yanked the charger out of the charge port and opened up the battery bay. That one pack was quite hot...too hot to comfortably hold in my hand for more than a couple of seconds. I took it into my garage and set it on the steel table of my table saw. I figured if it was on the verge of exploding, that was a safe place for it in the middle of a bunch of steel with lots of concrete around it. I stood there for several minutes and nada...the battery was cooling down, not going thermal. It obviously wasn't going to blow up despite being at 4.7 volts per cell and probably 150F. I periodically measured the cells and then waited til it got to room temperature again. They never wavered from 4.7 volts per cell. I then rigged up a load to pull them back down to less than 4.2 volts. They didn't warm up or have any problems like bloating. Once the pack was back in the safe zone, they went back in my scooter and road me around for another 3 months at 12S, but with a BMS on them. Later I pulled all my 12S packs apart and re-purposed them into 20S packs. After almost a year of use, one cell died. I still have those 20S packs and they are still working. They didn't suffer any loss at all, didn't explode and lasted just as long as the other packs that had not been abused. All I can say is oh well...I guess LIPOs are tougher than people think and so much of the concern is merely FUD (Fear, Uncertainty and Disillusionment).

If your packs are connected together at every balance point, no one pack can discharge faster than another despite the capacity differences between cells. If you are just pulling power from the plus and minus ends of each pack and there are no interconnects making all the cells in a particular channel into one large cell, then yes, whatever pack with the lowest capacity will drain down the fastest. This is one of the two reasons why I have them all connected together. If I don't then I need separate BMS for each pack. The batteries will try to discharge well below their bottom safe limits, if you don't have something to stop them. So your options are interconnect everything into a single big pack and run one large BMS or run each pack on its own smaller BMS independent of the other packs. As the packs discharge differently since they are independent of each other except for their power leads, they are each independently protected and shut off when they are depleted independent of each other. Below is my battery box over the back wheel. I could have done a neater job wiring together the 6 packs into one big pack, but it's all hidden and no one sees it except me.

Image

There are 6 of these 20S2P packs in the above picture. Those balance connectors are labeled 1 to 4. All the fours are connected together, all the 3's are connected together, all the 2's are connected together, etc. Its exactly like I welded up a 20S12P pack, but I can easily replace individual cells. No one pack can run down faster than another. At the end of a charge when I'm getting close to 60 volts, I have checked the packs separately and all the cells despite some being new 18650PF and others being used laptop cells measured the same voltage on the same channel because they are all electrically connected together in parallel over their balance wires. No one cell or group of cells can discharge faster than the rest of the cells they are in parallel with regardless of the disparity of capacities of cells in that group. If I took a single 20,000mah cell and discharged it, I would get 20,000mah of capacity, If I took 10 2000mah cells and connected them in parallel I would have 20,000mah of capacity and discharging them would get me 20,000mah. At the end of the test, if I measured the 10 cells in parallel and got 3.1 volts and then disconnected all the cells from each other, they also would individually measure 3.1 volts. I could take nine 2000mah cells and 2 1000mah cells and connect them all in parallel. Let's say I ran them down by 20,000mah and then checked the 10 cells in parallel and measured 3.1 volts. If I then disconnected the cells from each other and checked the individual cell voltages, they would each read 3.1 volts. The only time this would not happen is because you had a bad cell with a really high IR. With "good enough" cells or better, they are all going to show the exact same voltage despite there being some cells with much less capacity than others.

For typical laptop cells, stay under 3C and you will be fine. My original load tester drew 24 amps at 20S2P or 4.6C per cell on laptop cells. They got warm (90-100F), but not hot for the most part. 3C max discharge will be just fine.

Cell monitors...these Matek units are uber small and work pretty well for up to 6S. They display a single cell at a time, but the alarm is quite loud. Also, check out the celllog which is a little larger and good for 8S. They have an external alarm module so you can wire it up to your handlebars and leave the monitor in the battery box. Honestly, just get a BMS and a watt meter. Trust the BMS to do what it's supposed to do...protect your pack and then watch the pack voltage on the watt meter. The only time I would go with a cell monitor solution is on a skateboard where I don't have space to mount gauges. Even then, I would make room for a BMS on board. On a bike or scooter, moped, etc...just get a watt meter and BMS. I use cell monitors to randomly check out my packs. All the rest of the time the BMS is doing that job and getting it right.

http://www.ebay.com/itm/Matek-6S-Lipo-W ... SwPhdU~m~h

Digital thermometers and battery temp monitoring...
I don't monitor my battery temps ever. I just don't run them that hard. They never get warm enough to care. I have capacity so I can get down the road lots further and that means I never dig deep enough at any moment in time to push the overall discharge into the red zone to heat up the batteries. If you are wanting to build a pack small enough to need to watch them that closely then you are not going to get very far. In an RC quad copter where you want minimal weight, maximum discharge rates and expect 4-5 minute flight times, well a small pack is the only answer and yes, you are always running that pack close to it's maximums. For typical EV use, you want range and you want amps for those quick bursts of acceleration. To get range, means lots of Mah. To get amps for short bursts of acceleration means lot's of Mah and also a decent C rating. If you normally pull 20 amps and need 20 miles of range well that's probably something like 16,000-20,000 mah. IE: At 30mph it's going to take you 2 minutes to go a mile so 20 miles is 40 minutes riding continuously at 30mph. A 16,000mah hour pack running at 16,000mA will run down in one hour so 20 amps and 20 miles equates to about 16-20 thousand mah. AND the really important thing is a 20,000mah pack with a 20 amp load on it is 1C discharge. That pack will never get above ambient so what's the point in ever measuring it's temperature? Even at 2 or 3C or 40-60 amps, that pack is going to stay nice and cool. If anything, if I am riding hard...I mean really hard, I will pop open the battery covers and put my hand on tops of the packs and they are slightly warmer than ambient. Battery temp monitoring...meh...not needed. Motor temp monitoring...well that's a different thing and I would have to say most definitely yes to that!

This is a basic digital temp meter. I use them in my motors. If you look at my scooters, you will see one mounted on the console. I think i paid like $6 each for them.

Little meters like this can serve dual purposes. Use the exterior temp sensor for measuring your motor temp and use the interior sensor to measure ambient air temperature. I know that's backwards of what it says on the LCD, but it doesn't really matter. The assumption for these kinds of devices is that you will mount it on the dashboard of your car and put the remote sensor somewhere outside your car. Who cares where you locate the remote sensor. It's going to measure the temperature at that location. If you really want to get crazy, the interior sensor is soldered to the circuit board in the meter, unsolder it, add some length of wire to it and locate the sensor where you want it.

http://www.ebay.com/itm/Car-F-C-Thermom ... 0734918238

http://www.ebay.com/itm/2colors-Aquariu ... DwAbRTvZjg

Or if you really want to get crazy, get one with a clock and compass and dual temp sensors.

http://www.ebay.com/itm/Car-Digital-Com ... 1762471600

This is the temp guage I use on my EV projects. Cheap, compact, F or C measurement. Needs 5 volts to run. Bright color LCD.

http://www.ebay.com/itm/262558775808?_t ... EBIDX%3AIT
Okami wrote:Cool, lots of more info to process now.. :)

I tested the cell pack I got - the 4S2P one and it showed that 3650mah were pumpet into the pack, so about 1800mah per cell, just as I ''predicted'' as I also foolishly bought these 2 packs (I got 2 of them) from ebay for about 2 eur per battery, (16batteries and ~35eur cost).

Too bad I did not know about nkon eu site back then but okay from nkon the shipping cost would be 11 eur itself, so I would probably get ~10 batteries but they would be new at least.. not 1-2yr used in medical devices..

------

So yeah, that's the price I payed for jumping into li-ion battery tech too early.. I had about 6-10 batteries laying around, and 6 of them were panasonic CG variety, so I thought not to have mixed brand batteries I should go with the same brand and there was a listing for such 'medical' use batteries. If there were not a word medical, I probably would not have bought them.. It is just the pure coincidence that a few days earlier or a week earlier I saw someone mentioning (perhaps on battery university) that in medical field the li-ion batteries are tossed away way before their time, as they replace the batteries on a timely basis not the actual capacity or such.. as devices which rely on them cannot stop at all costs so the risk of a battery stopping is too great and they replace the batteries once they have reached their deadline..

So yeah, instead of 2250mah for new batteries I got 1800 mah per battery just as I speculated (around 300 cycles used or so)
-----
Okay, so that's the end of side story on how I got tossed into choosing li-ion, as initially I thought about going with lipo's but I disliked the risk of fire (considering lipo safe bag) and also the short lifespan of them..

Anyways, so now Im gonna combine laptop grade - low discharge cells with high discharge ones, and check how well they perform!

---

From what you @ElectricGod told me, I can conlude that I should expect one pack to be drained faster.. and that's all. As of now I will probably have laptop grade pack with less capacity, so I speculate that it will be drained faster than the high discharge pack.

I will probably try to make some more tests to see at what discharge rate the cells start to get hot, so that I would know how much can I drain them.. Will also fit lipo alarms on these packs but what I dont like is that these cheap lipo alarms dont show very precise cell voltages and usually there is quite a big drift in accuracy they show.. perhaps I just got a bad ones.. which dont show correct per group/cell voltage but still show good total voltage.

So probably should think about a bit better per cell/group voltage monitors, which does not start to beep annoying when one of the cell group's start to seemingly drift below the set voltage treshold..even if they are a few milivolts on top of it.

---

On a side note - I actually wanted to tell that some ppl have placed regular digital termo-meters in their pack or close to motor.. of course you dont get the benefits like visual indicator our sound out of them.. but if you manage to mount these in your panel (if you have one), then it might be a cheap way to check temp's once and then..
How ever you do your LION packs...lets say 12S...then all the cells in parallel at 1S, connect them together. I do it via the balance cables, but whatever works for you. Same for the 2S cells and 3S and 4S... In my Currie scooter, I currently have 3 10,000mah LIPO packs. This is fine for now since it is still getting built, but I know I won't have the capacity I want.
Last edited by ElectricGod on Aug 30, 2017 5:52 pm, edited 1 time in total.
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Re: My excellent adventure through some battery builds

Post by Ianhill » Dec 21, 2016 10:00 pm

I've seen barbecue temp sensors been hacked so the display is free of the probe to be moved but im sure it skewers the results get it ;), they do have a very wide range of temp though right the way upto extra crispy.
Some cracking info on this thread to amalgamate.
Can't wait to see the mod lighting big block she gonna be a bad bad scooter at 118v pity your the other side of the pond, We could of started doing cash days run what you brung no prep racing 1/8th mile drags best scooter wins no crossing the centre line, stage up to the line, go on the flash light, no jumping and most of all get them back tyres hooking, it be great big ass slick on the back with chunky drag type alloy rim with wheeley bars and a skinny useless tyre on the front just floating down the track dumping a quick 20kw burst or more I'd love it.

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Re: My excellent adventure through some battery builds

Post by Okami » Dec 22, 2016 5:30 am

There's no such thing as "too early" when it comes to LION. How else are you going to learn other than to make a few mistakes along the way and of course to read what others did?
Yeh, my mistake was to buy some used - overpriced cells when I just could have ordered new and no testing would have been needed :)

The good side, of course, is that, I got into Li-ion mindset.. because most of the e-skateboard builders just grab some lipo's as they seem to be a cheaper and less-effort demanding solution and this works for them quite okay, though the ones who use their boards more get to witness the decline in capacity / range after a while..

Li-ions cost quite a bit more, so if the person is not putting his own work into making the battery pack, it will probably cost initially more than a cheap lipo pack, which you might replace after a year anyways..

Though, it seems now, that there are more and more ppl who consider and turn to li-ions instead of using lipo's, as there are quite a lot of ppl who are still very cautinous about using lipo's. I've also seen at least 2 ppl who have just bought the lipo's and ran them down as hard as they could.. only to later realize that the battery is damaged and each cell has a very drastic voltage difference (I think some cells had 1.5v, some 2.5v something)

I'll have to look into medical packs. They probably are in better condition than a typical laptop pack which gets tossed because the user is getting less than their expectations from battery run time.
Hah im glad I made you to think about these cells used for medical purposes.. Well, I got my 2 packs from German seller, the packs were in 4S2p config, unfortunately these are not high-power cells and neither high capacity!

Datasheet is here:
http://www.meircell.co.il/files/Panason ... 8650CG.pdf

2250 mah, about 2C recommended.

For some odd reason the laptop I had and torn apart had these green CG cells in it. Since the brand ''Panasonic'' seemed to be way better than the blue no brand cells I had got from another laptop battery, I thought to myself.. mhh why not get some more cells like these, then they will have matching stats and they should be more reliable..

At that time I had already thought about going the scavaged laptop battery path but I just feared the dreadful tests and time I would need to spend on testing these cells because at that time I had no balance charger at hand to see the real capacity..

So yeah, anyways, I blame myself for buying these used cells for quite a high price.. but at least that quickly threw me to research more and get some good quality cells.. later on I actually found an e-bike builder which was able to offer me cells for lower price than on that nkon (eu) battery site.

--
My watt meter read 56 volts. I yanked the charger out of the charge port and opened up the battery bay. That one pack was quite hot...too hot to comfortably hold in my hand for more than a couple of seconds. I took it into my garage and set it on the steel table of my table saw. I figured if it was on the verge of exploding, that was a safe place for it in the middle of a bunch of steel with lots of concrete around it. I stood there for several minutes and nada...the battery was cooling down, not going thermal.
Very cool battery story! Did not know that a cell can be pushed so far! I've heard 4.3-4.4 is on a risk zone.. but 4.7 is beyond that!

I have friend who actually burnt his drone down.. he left lipo batteries unattended and foolishly he did not balance charge.. just bulk charged them.. Im not sure what charger he had.. but it seems his allowed to charge in non-balance mode, too (mine does not allow that)... So.. anyways when he returned there was quite a lot of smoke and his drone and batteries had turned into coal.. frame was still ok, as he had a carbon fibre one..

It later turned out / the thoery was that he had a shorted cell and a cell probably got overcharged, which caused the fire. He also mentioned that he had crashed quite a lot of times with the drone.. so it was not so surprising that a cell / battery was perhaps damaged.

--
If your packs are connected together at every balance point, no one pack can discharge faster than another despite the capacity differences between cells. If you are just pulling power from the plus and minus ends of each pack and there are no interconnects making all the cells in a particular channel into one large cell, then yes, whatever pack with the lowest capacity will drain down the fastest.
I will definately take a look into this! This seems like something I have missed.. basically, I think it is very logical.. Otherwise how else we might be able to increase total capacity of the pack, if we did not add similar sized blocks next to each other? The only difference here is that, some blocks might be smaller or have different capacity but that does not change the fact that the rest of the blocks ''keeps the level''.

I had heard a lot of speculation and uncertainity about cells pumping current into the weaker cell.. So that also left me in the blank spot.. what happens at discharge and what happens at rest period, if such a process happens.

I know there is balancing action when you connect different voltage cells together, though, for me it seems, the cell takes what it can take and no more, I measured the amps of 14500 cell, and it was around 0.75a I believe.. Once the voltage level of both cells leveled out, the amps decreased. The other cell (from which I ''charged'' - balanced the 14500 cell, was the regular 18650 cell)

----

Im using these ''the chepeast you can ever find'' voltage alarms/monitors:
http://www.ebay.com/itm/1-8S-2-in1-RC-L ... Sw0RpXlf9t

I would not really recommend them, as they are quite annoying, though, they work okay to moderately accurately tell how much volts the cells have but it is annoying, if you have set them to 3.4 and they start buzzing at least 2-4min before the real cell voltage has declined that low. In my case, it has 'bad readings' on the last 2 cells out of 6, one was way higher and the second one was way lower...

To somehow silence the loud sound it is possible to just tape the vents from where the sound comes..

Though, if the money allows, these cellogs seems to be the best and nicest looking option, as the voltages are shown all at once and it seems to be a good display to look at..

These Matek voltage monitors looks like to be a really good middle ground between the cheap and the expensive voltage monitors :) Too bad they're only 6s, 8s would have been better.

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 22, 2016 1:44 pm

Ianhill wrote:I've seen barbecue temp sensors been hacked so the display is free of the probe to be moved but im sure it skewers the results get it ;), they do have a very wide range of temp though right the way upto extra crispy.
Some cracking info on this thread to amalgamate.
Can't wait to see the mod lighting big block she gonna be a bad bad scooter at 118v pity your the other side of the pond, We could of started doing cash days run what you brung no prep racing 1/8th mile drags best scooter wins no crossing the centre line, stage up to the line, go on the flash light, no jumping and most of all get them back tyres hooking, it be great big ass slick on the back with chunky drag type alloy rim with wheeley bars and a skinny useless tyre on the front just floating down the track dumping a quick 20kw burst or more I'd love it.
Absolutely...did not think of taking apart a cooking thermometer for EV use. So many of the little temperature modules like for cars have a limited sensing range. Above 140F and most of them are useless. A cooking thermo on the other hand needs to read temps at freezing all the way up to like 500F.

We could have fun ripping up and down the country side. I'm pretty sure I'm a good bit faster than you on my blue scooter. The big block will probably stay shelved for a while until I finish up the Currie. It's getting closer all the time. 4000 watts on a 60 pound scooter ought to be hilariously fun.

I've been looking at hybrid car motors. I think 4 SUV motors...one per wheel.. on a smallish car like a mini would be a real kick. All wheel drive, no drive train, direct motor to wheel drive and then run it at 500 volts or whatever. I can see getting a legit 0-60 in 3 seconds or less...that's super car numbers...kind of results. This wouldn't be a vehicle meant for range, but rather raw unadulterated balls to the wall power and acceleration. It would be fun to drive it on regular roads. It would look ordinary, but then be a rocket. LOL...have retractable wheelie bars on the back. Hit a switch and a motor runs them out behind the car. Flip it the other direction and they retract into a hidden compartment.

A 20KW stand-up scooter....you would probably use LIPO just because of the monster discharge rates you can get from them that you can't get from LION without tons or paralleled cells. With LIPO some 50C 20,000mah cells could get you 100 amps. Several in parallel could get you the wattage you want for the minimal amount of weight. You get on, act all casual like...despite the monster motor hanging over the back wheel...creep up to the line in uber low power mode...flip a switch for "balls to the walls" mode and wait for the light to turn green. Then lean way over the handle bars just to keep the front end down and the light turns green and you are off. 60mph in 2.2 seconds and you haven't even gotten halfway up to full motor RPMs. Sign me up!!!
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Re: My excellent adventure through some battery builds

Post by Ianhill » Dec 22, 2016 3:31 pm

A 20s2p lipo pack with 10000mah 15c cells would be up to the job of 25kw in short bursts and weigh 9kg and I'm sure it would be lighter with 5000mah 65c cells just less capacity. I love the idea of the mini the only thing about hub motors on a car is the wheels look a bit silly and its all sprung weight but for a flat out drag car it would be fine.
You would leave my scooter in dust no doubt I'd be the hustlar taking all the bets like big chief then one day I'll join the game with my own promod scooter.
There's a big push in cells coming from the UK soon 5* current density means the whole game will flip on its head soon and gas cars will be seen as the pain in arse need to fill them up all time.

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 22, 2016 3:47 pm

Ianhill wrote:A 20s2p lipo pack with 10000mah 15c cells would be up to the job of 20kw in short bursts and weigh 9kg and I'm sure it would be lighter with 65c cells, I love the idea of the mini the only thing about hub motors on a car is the wheels look a bit silly and its all sprung weight but for a flat out drag car it would be fine.
You would leave my scooter in dust no doubt I'd be the hustlar taking all the bets like big chief then one day I'll join the game with my own promod scooter.
There's a big push in cells coming from the UK soon 5* current density means the whole game will flip on its head soon and gas cars will be seen as the pain in arse need to fill them up all time.
Storage capacity is the big hurdle to get electrics into the mainstream market. %0 miles just isn't close to enough range for a car. I want to be able to drive like I do with my ICE car. The whole idea of an hour+ lay over every time I need to charge is fine if I'm going home and not going back out, but if I'm going from state to state...that's like 2 tanks of gas and a 10 minute stop to fill up once in the middle and then I'm on the road again. Recharging needs to be a 10 minute event and then get you 300 miles of distance. Of course never charging is a really great option too. Fuel cells are stunningly effective and filling a bottle with hydrogen is fast. Of course the moment people ubiquitously have a mobile 20Kw power plant is the end of the power companies and their huge monopoly on electric power generation. If we all had fuel cells in our garages, we would totally have no need for the grid since we would all be energy independent. The power companies are big and powerful, they'll never let that happen. Same for the all magnetic motors like the perendev...some powerful self interested party will always see things that require no fuel source as a threat to their power and money stream will always bury anybody that tries to create and market them. With an all magnetic motor generating electricity, all you need is a small battery supply to take up the surges and then you depend on the magnetic motor and generator attached to it for all the normal power needs.

I wouldn't do hub motors because of the unsprung masses at the wheels. I would put the motors inboard in the center of the chassis and run a shaft out to wheel. Cars have been running that way for a very long time and it works really well.

I was reading about a new LIPO development where it gets 3X the capacity of current LIPO for about the same weight and size. That would be stunning. It would put LIPO leaps ahead of anything in the LION world.
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Re: My excellent adventure through some battery builds

Post by Ianhill » Dec 22, 2016 5:02 pm

When lipo goes 3× capacity I hope they use it to make like 35ah packs etc instead of just compacting the current cell capacity's, Things look very good and optimistic for electric motion and generation moving forward on all fronts its a good time to be living if the news is turned off and papers burned.

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 22, 2016 7:45 pm

Ianhill wrote:When lipo goes 3× capacity I hope they use it to make like 35ah packs etc instead of just compacting the current cell capacity's, Things look very good and optimistic for electric motion and generation moving forward on all fronts its a good time to be living if the news is turned off and papers burned.
Yeah and ignore all the government hype.

The way tech in so many ways is advancing it's definitely a cool time to see history in the making. In 50 years, I wonder what they will remember us for? Cold fusion, crazy battery advancements where you get 10,000mah at 100C in a 1 ounce package? Who knows!
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Re: My excellent adventure through some battery builds

Post by Ianhill » Dec 22, 2016 8:05 pm

I don't know what your age is but I'm 31 so hopefully I get to see Chernobyl become fully dissembled and maybe get to see an age where nuclear waste is useful no longer will we think of putting our problems in the ground for future generations to experience the catastrophe.
Energy density for weight in a battery is apparently possible to exceed gasoline and maybe way beyond but that would really be the nail in the coffin for transport as we know it but like we all know there's so many money hungry greedy factors involved.

Off topic but at EG.
I found that for 1khz to 10khz a winding made up of 30awg wire is the sweet spot, the bomas max out around 400hz so it could possible use multiple 28awg to make up the 35amp rated with not much issue but i would rewind it with 30awg if it will spend most of its life at high rpm when i get some spare time i will wind one maybe the one i use for the next project get a tad more beef out of it and lock the rotor up while its apart for a major rebuild of a barely spun brand new motor but its a 48v 1600w so I may sell it buy a 2000w then strip that one :) but I guess thats whats makes us potchers, here's the chart I found
Theory_Table2.jpg
Ac skin effect conductor choice guide.
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 22, 2016 8:47 pm

Okami wrote:
There's no such thing as "too early" when it comes to LION. How else are you going to learn other than to make a few mistakes along the way and of course to read what others did?
Yeh, my mistake was to buy some used - overpriced cells when I just could have ordered new and no testing would have been needed :)

The good side, of course, is that, I got into Li-ion mindset.. because most of the e-skateboard builders just grab some lipo's as they seem to be a cheaper and less-effort demanding solution and this works for them quite okay, though the ones who use their boards more get to witness the decline in capacity / range after a while..

Li-ions cost quite a bit more, so if the person is not putting his own work into making the battery pack, it will probably cost initially more than a cheap lipo pack, which you might replace after a year anyways..

Though, it seems now, that there are more and more ppl who consider and turn to li-ions instead of using lipo's, as there are quite a lot of ppl who are still very cautinous about using lipo's. I've also seen at least 2 ppl who have just bought the lipo's and ran them down as hard as they could.. only to later realize that the battery is damaged and each cell has a very drastic voltage difference (I think some cells had 1.5v, some 2.5v something)

I'll have to look into medical packs. They probably are in better condition than a typical laptop pack which gets tossed because the user is getting less than their expectations from battery run time.
Hah im glad I made you to think about these cells used for medical purposes.. Well, I got my 2 packs from German seller, the packs were in 4S2p config, unfortunately these are not high-power cells and neither high capacity!

Datasheet is here:
http://www.meircell.co.il/files/Panason ... 8650CG.pdf

2250 mah, about 2C recommended.

For some odd reason the laptop I had and torn apart had these green CG cells in it. Since the brand ''Panasonic'' seemed to be way better than the blue no brand cells I had got from another laptop battery, I thought to myself.. mhh why not get some more cells like these, then they will have matching stats and they should be more reliable..

At that time I had already thought about going the scavaged laptop battery path but I just feared the dreadful tests and time I would need to spend on testing these cells because at that time I had no balance charger at hand to see the real capacity..

So yeah, anyways, I blame myself for buying these used cells for quite a high price.. but at least that quickly threw me to research more and get some good quality cells.. later on I actually found an e-bike builder which was able to offer me cells for lower price than on that nkon (eu) battery site.

--
My watt meter read 56 volts. I yanked the charger out of the charge port and opened up the battery bay. That one pack was quite hot...too hot to comfortably hold in my hand for more than a couple of seconds. I took it into my garage and set it on the steel table of my table saw. I figured if it was on the verge of exploding, that was a safe place for it in the middle of a bunch of steel with lots of concrete around it. I stood there for several minutes and nada...the battery was cooling down, not going thermal.
Very cool battery story! Did not know that a cell can be pushed so far! I've heard 4.3-4.4 is on a risk zone.. but 4.7 is beyond that!

I have friend who actually burnt his drone down.. he left lipo batteries unattended and foolishly he did not balance charge.. just bulk charged them.. Im not sure what charger he had.. but it seems his allowed to charge in non-balance mode, too (mine does not allow that)... So.. anyways when he returned there was quite a lot of smoke and his drone and batteries had turned into coal.. frame was still ok, as he had a carbon fibre one..

It later turned out / the thoery was that he had a shorted cell and a cell probably got overcharged, which caused the fire. He also mentioned that he had crashed quite a lot of times with the drone.. so it was not so surprising that a cell / battery was perhaps damaged.

--
If your packs are connected together at every balance point, no one pack can discharge faster than another despite the capacity differences between cells. If you are just pulling power from the plus and minus ends of each pack and there are no interconnects making all the cells in a particular channel into one large cell, then yes, whatever pack with the lowest capacity will drain down the fastest.
I will definately take a look into this! This seems like something I have missed.. basically, I think it is very logical.. Otherwise how else we might be able to increase total capacity of the pack, if we did not add similar sized blocks next to each other? The only difference here is that, some blocks might be smaller or have different capacity but that does not change the fact that the rest of the blocks ''keeps the level''.

I had heard a lot of speculation and uncertainity about cells pumping current into the weaker cell.. So that also left me in the blank spot.. what happens at discharge and what happens at rest period, if such a process happens.

I know there is balancing action when you connect different voltage cells together, though, for me it seems, the cell takes what it can take and no more, I measured the amps of 14500 cell, and it was around 0.75a I believe.. Once the voltage level of both cells leveled out, the amps decreased. The other cell (from which I ''charged'' - balanced the 14500 cell, was the regular 18650 cell)

----

Im using these ''the chepeast you can ever find'' voltage alarms/monitors:
http://www.ebay.com/itm/1-8S-2-in1-RC-L ... Sw0RpXlf9t

I would not really recommend them, as they are quite annoying, though, they work okay to moderately accurately tell how much volts the cells have but it is annoying, if you have set them to 3.4 and they start buzzing at least 2-4min before the real cell voltage has declined that low. In my case, it has 'bad readings' on the last 2 cells out of 6, one was way higher and the second one was way lower...

To somehow silence the loud sound it is possible to just tape the vents from where the sound comes..

Though, if the money allows, these cellogs seems to be the best and nicest looking option, as the voltages are shown all at once and it seems to be a good display to look at..

These Matek voltage monitors looks like to be a really good middle ground between the cheap and the expensive voltage monitors :) Too bad they're only 6s, 8s would have been better.
Weight, cell size and charge density, 18650's of today beat modern LIPOs, but LIPOs are cheaper for the same charge capacity and have much higher discharge rates. Lots of people make the decision to buy LIPO rather than LION just because they can get RC packs with the same capacity at 65% the price of LION and it will have much higher discharge rates. However LION will out last LIPO 3 to 1 so in the longer run, LION is way cheaper than LIPO. LIPO is good for 200-300 charge cycles and LION is good for 600-900 depending on the cells and use case. That's a significant improvement in life span. I still buy LIPO...they have their place, but I would prefer to always use LION if I could afford them.

I think a lot of folks think in terms of RC stuff exclusively when it comes to boards. Yo can use RC parts for 100% of the build out. Well that's fine, but also RC typically doesn't think in terms of battery protection or charging in the EV...which is dumb IMHO. As a result people do things like run their packs down to dead.

If you take apart Chinese battery packs, they will have 18650's in them, but they tend to not be made as well as similar capacity and discharge rated cells from LG or Samsung or Panasonic. When I first built out my LION battery holders, I was short about 40 cells so I got on ebay and bought several Chinese laptop packs for as cheap as I could find. I tested the cells and they were supposed to be 2600mah, but none of them were...more like 2000-2200 which was disappointing. I contacted the seller and told them what I found and they gave me a partial refund for less than advertised capacity. The above picture of a 20S2P battery holder was populated with those Chinese cells. Over time I found that despite them being brand new, they failed or got weaker much faster than the used cells from name brand battery packs. LOL! Lesson learned...buy name brand cells because you get what you pay for.

I have run without balancing for a while...month at a time, but I don't go long term that way and I'm checking the packs to make sure I'm staying close to balance. From the perspective of the EV, 82 volts looks like 82 volts. The EV can't tell that there is a cell at 4.7 volts and another at 2.2 volts. So it just runs and draws down the overall voltage to the system cut-off point. That is a huge reason why a BMS is so valuable. I balance charge in the EV with every charge and never run down a cell too far or over charge anything. People doing RC conversions to EV often times don't think about what their balance charger is doing and so they never check if their packs stay balanced once they stick them in their EV. Whatever battery solution you use, LIPO, LION, SLA, LIFE, NiMh...whatever...balance charging still matters. you never want to over charge a battery and you never want to run it down below it's safe bottom voltage.

Adding cells together to make a larger pack...
It is best to use similar capacity cells together in parallel. Using a stronger cell to bolster a weaker cell is not the best practice. It can be done without harm to anything, but for best capacity and battery use, just use similar capacity cells everywhere. Remember my "good enough" number of 2000mah? That was my baseline for similar capacity cells. AS long as everything I was using had at least 2000mah of capacity, then that was my lowest common denominator and my riding to and from work and my charge cycles were based on that number. Above and beyond that 2000mah is pure extra that I don't count on. As a result, effectively I never run into the issues where a cell might be completely discharged in parallel with a cell that still has remaining capacity so that back charging happens between cells to keep them all at the same voltage. There have been a couple of times where I got right down to 60 volts when I got home. I'm sure in that scenario, that a fair bit of back charging had occured, but when I opened the battery bay and checked each pack individually, all the cells in the same position in the packs all had the same voltage. IE: Multiple cells connected together can't have a different voltage from each other. Whatever the aggregate voltage is for all of the cells is also the voltage of any single cell.

Recovering cells...
When I tear open a used laptop pack, it is not uncommon to have cells that are under voltage by quite a lot. This last weekend I took apart 6 packs and found several cells that were down in the 1-2 volt range. I took those cells and put them in a 1S4P battery holder I built some time ago with a weak, but charged battery. The weak battery can't deliver lots of current because of its overly high IR and it has limited capacity anyway so there's little chance that one fully charged cell is going to over power 3 very low voltage cells and put things in a dangerous state. The end result is the super low cells quickly come up to higher than 3 volts and then I can charge them normally at full current. I have recovered probably 20-30 badly discharged cells this way. Some have significant capacity loss, high IR or wont charge fully, but some are just fine after recovery. You don't know until you try. I have 8 or 10 cells that were part of a collection of dead flat cells I came across in several packs. I don't remember the exact number, but about half of them recovered and the other half would never take a charge. About half of the recovered cells returned to good functionality and upon load testing were "good enough". I've recovered LIPO cells with another LIPO of much less capacity. The results are about the same. About a year ago, Someone I used to be in touch with all the time had built a small scooter and had no BMS on it. He ran his turnigy 12,000mah ^S LIPO packs down way too far. He was afraid of them exploding and of trying to recover them. I bought the packs from him for $40 knowing that each pack had multiple cells currently in the 2 volts range. One pack had a badly bloated cell in it and the other looked completely normal. I checked each cell and then used a weak LION cell on each depleted LIPO cell to get it's voltage back up above 3 volts. Once they were all close to the same voltage again, I hooked up the balance connector to my RC charger and charged the pack at 3 amps. They both charged right up. Some time later, the bloated cell petered out and so I removed it and now I have a perfectly good 5S pack and a 6S pack. I've used both of them in EV stuff multiple times and they work just like any other LIPO does. When I run them down they do have some loss of capacity, but that may be simply from him using them for 3-5 months before I got them. None of the cells deplete faster than the others.
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 22, 2016 9:23 pm

Ianhill wrote:I don't know what your age is but I'm 31 so hopefully I get to see Chernobyl become fully dissembled and maybe get to see an age where nuclear waste is useful no longer will we think of putting our problems in the ground for future generations to experience the catastrophe.
Energy density for weight in a battery is apparently possible to exceed gasoline and maybe way beyond but that would really be the nail in the coffin for transport as we know it but like we all know there's so many money hungry greedy factors involved.

Off topic but at EG.
I found that for 1khz to 10khz a winding made up of 30awg wire is the sweet spot, the bomas max out around 400hz so it could possible use multiple 28awg to make up the 35amp rated with not much issue but i would rewind it with 30awg if it will spend most of its life at high rpm when i get some spare time i will wind one maybe the one i use for the next project get a tad more beef out of it and lock the rotor up while its apart for a major rebuild of a barely spun brand new motor but its a 48v 1600w so I may sell it buy a 2000w then strip that one :) but I guess thats whats makes us potchers, here's the chart I found
Theory_Table2.jpg
Greed, hunger for power and selfish self interest run way too many things. Those aren't bad in themselves. They are powerful motivators to be sure, but they need to be kept in check with what's the greater good and what benefits others while I'm benefiting myself. Nuclear power plants when they were first conceived had the balance in mind...despite producing lots of radioactive waste. They were supposed to be long running, safe sources for lots of electricity. Of course the military saw that a few reactors around the country were a wonderful source for plutonium for making nukes. If we have an asteroid tumbling towards the Earth, nukes might be good for blowing it up, but otherwise they serve no good purpose. They don't deter wars or terrorism in any way. I say ban all of them. Anyway, so many times personal greed and hunger for power over whelms the "good for everyone" and then you get Chernobyls and the refusal to move away from uranium fission reactors in favor of thorium reactors or fusion or other means of generating power that are much cleaner and better. GRRR! The total lack of concern for the well being of everyone else, gets us gasoline when we should have long ago moved away from ICE. THe problem is a car that can run for 10,000 miles and never need to refuel makes you NOT need the people in power that are holding us down with their stranglehold on the 10,000 miles between stops car. So they won't let things like fuel cells and magnetic motors and thorium reactors or even really efficient ICE to be main steam. They would quite literally put themselves out of business! But yes, it would be fantastic if the world 100% moved away from uranium powered reactors in favor of thorium reactors or other actually safe and clean power sources.

I think battery capacity research is handicapped by the oil companies. I'm not much into conspiracies, but I do acknowledge that they happen. Batteries the size of an 18650 that had 20,000mah capacity would absolutely shut down the gas companies. Think of the battery bay in a tesla S full of 18650 sized cells with 20,000mah each. That car could cross the entire USA on a single charge. I would never buy gas again. I'd sell my SUV or convert it to electric. But as things are, electric cars are too expensive and they always have limited range which always keeps them out of the mainstream which is owned by the ICE and gas companies. Anyway, I think it's something that every executive in every oil company around the world has thought about as a minimum...how to slow the advancement of electrics so I don't lose my job. Stupid, greedy people!

Nuclear waste...At great expense we could launch it into the sun or onto the moon or at Jupiter...anywhere, but Earth. BUT...I think that nuclear waste is an unexplored resource that we just don't know how to use yet. There's lots of energy in radioactivity. I think it can be converted into something useful and safe and that way we don't throw away a valuable natural resource. The radioactive materials were already here scattered around the planet, we just mined them and concentrated them together so that being around the concentrated quantity that's stored in various salt mines around the world is dangerous. If we spread them back out like they were originally found, there would be no problem. Of course I'm not suggesting sprinkling radioactive wast all over the planet...just that originally that's how it was until we mined it.

I'm almost 50. I remember in 7th grade seeing an apple 2 computer for the first time and I was hooked.

Interesting chart. Well I guess I'm a little over sized with my 28 awg wire for the 80-100, but then I intend to lower the KV a little. I doubt it will be a problem. If skin effect was the only issue, then everybody would wind with 30 awg wire, but it's not. Many small diameter wires are lots less space efficient than fewer larger wires. If you look at my outrunners, all of them have 30-32 awg wire despite some having very low KVs. Then look at my inrunners and the wire strands are much thicker in all of them...more like 18 awg. Inrunner or outrunner...shouldn't make a difference. Even the AStroflight motors are wound with 20 awg strands and they are among the best motors out there. Skin effect is just one of many factors to consider.
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Re: My excellent adventure through some battery builds

Post by Ianhill » Dec 22, 2016 10:41 pm

Very interesting read lots of topics by there and most of it is spot on I have a great interest for space.
I like the idea of sending the waste to the sun if we could get a 100% reliable way of escaping earth's gravity then sending it to the biggest inferno in the vicinity makes sense but gaurented save the sun activist would come out with their pitch forks.
I was a commadore 64 guy running my tapes flashing colours all over the screen to play outrun even had to command prompt the game to start those were the days I had a simple non restricted upbringing no Facebook or phones just simple times up the mountains playing in the tip lighting fires with the owner back when we burned our rubbish he would sneak us a fag then we would go get frogs or newts or he would have salvaged us push bikes so we would terrorize the valley with bottles in the back wheel thinking we sounded like motorbikes, kids these days I don't know what going to become of them we shoving to much seriousness down their neck too young it a recipe for a generation that literally brakes down with tech and input overload.
The pereodic table is arangened in atomic numbers least to highest with all the nuclear stuff right at the top the most dense materials i think its because it easier to start the chainreaction with in them then we have different isotope of the same element and radioactivite decay and radioactivity two crazy things a very dangourous element we can add some protons to it and it becomes stable and less radioactive or make something failry safe into a very volatile substance that will release energy with an electron being fired at it, The half life of all the different elements some lasting just seconds or less or some upto hundreds of thousands of years then theres alpha gamma and beta particles from different radiating sources all dodgy stuff but very intreging as its what mother nature has used for Lego blocks to build us and everything we see we are in the goldie locks zone very damn lucky to be writing a message on a touch screen phone developt by my fellow chinnese humans and those who came before them and me that developed a language/s and all other matter of stuff that made today yesterday and tomorrow possiible but we still have people that want to war I wish I could have an injection that could stimulate even the most ignorant to see some sence of it all and respect what we have inherited.
I do not see tech as evil but it can be overloaded and some live a very digital life I would be lost without the internet to get resources from and learn new things but others just use it for Facebook or tweeting about every damn thing they do like they got alsimers or summat even photo they dinners for god sake.
I still have the same family of newts I brought home around 23years ago from the mountain to my pond as a child, obviously they have died and its their past generation i rescued but that's my interaction that has gave them a place to live where now all windmills stand and there is no more newts or frogs I'm their lord saviour himself the land is no entry and kids rarely play anywhere but the park its just sad broken times too publicly correct while others rape the land, end of rant now only great build plans and help to others and tips for new year and beyond from me.

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 23, 2016 10:14 pm

Ianhill wrote:Very interesting read lots of topics by there and most of it is spot on I have a great interest for space.
I like the idea of sending the waste to the sun if we could get a 100% reliable way of escaping earth's gravity then sending it to the biggest inferno in the vicinity makes sense but gaurented save the sun activist would come out with their pitch forks.
I was a commadore 64 guy running my tapes flashing colours all over the screen to play outrun even had to command prompt the game to start those were the days I had a simple non restricted upbringing no Facebook or phones just simple times up the mountains playing in the tip lighting fires with the owner back when we burned our rubbish he would sneak us a fag then we would go get frogs or newts or he would have salvaged us push bikes so we would terrorize the valley with bottles in the back wheel thinking we sounded like motorbikes, kids these days I don't know what going to become of them we shoving to much seriousness down their neck too young it a recipe for a generation that literally brakes down with tech and input overload.
The pereodic table is arangened in atomic numbers least to highest with all the nuclear stuff right at the top the most dense materials i think its because it easier to start the chainreaction with in them then we have different isotope of the same element and radioactivite decay and radioactivity two crazy things a very dangourous element we can add some protons to it and it becomes stable and less radioactive or make something failry safe into a very volatile substance that will release energy with an electron being fired at it, The half life of all the different elements some lasting just seconds or less or some upto hundreds of thousands of years then theres alpha gamma and beta particles from different radiating sources all dodgy stuff but very intreging as its what mother nature has used for Lego blocks to build us and everything we see we are in the goldie locks zone very damn lucky to be writing a message on a touch screen phone developt by my fellow chinnese humans and those who came before them and me that developed a language/s and all other matter of stuff that made today yesterday and tomorrow possiible but we still have people that want to war I wish I could have an injection that could stimulate even the most ignorant to see some sence of it all and respect what we have inherited.
I do not see tech as evil but it can be overloaded and some live a very digital life I would be lost without the internet to get resources from and learn new things but others just use it for Facebook or tweeting about every damn thing they do like they got alsimers or summat even photo they dinners for god sake.
I still have the same family of newts I brought home around 23years ago from the mountain to my pond as a child, obviously they have died and its their past generation i rescued but that's my interaction that has gave them a place to live where now all windmills stand and there is no more newts or frogs I'm their lord saviour himself the land is no entry and kids rarely play anywhere but the park its just sad broken times too publicly correct while others rape the land, end of rant now only great build plans and help to others and tips for new year and beyond from me.
I don't know what you think about alien life, but to me life out there in space is the only logical conclusion and that life has been occurring out there for billions of years. Most of that life, probably 80% of that life is so different from us that just recognizing it as life would challenge our puny minds. The rest of that life would still be so different from us that probably 80% of that life would be difficult for us to understand and the remaining would understand us, but we probably would understand 20% of them at any kind of reasonable level. Much of that life is very advanced and has technology that we would think was miraculous and probably wouldn't even recognize as technology. I think that is the nature of the various gods this planet has known over the millenia...very advanced life from other worlds. I think that if there is are answers to our problems on this world, that they have already been found a million times by a million other worlds and it is just a matter of time until we too find those answers assuming we don't destroy ourselves before then. Among those answers are what to do with out nuclear waste and what to do with greedy and power hungry people that oppress the world for their selfish gain. I don't think good and bad are inherent in the soul, it's a behavior that you learn or choose or have reinforced over and over. So getting world change is a matter of learning better ways of thinking and behaving. On an individual basis, my changes in thinking and behaving have no effect on society as a whole, but multiply that by many thousands of people making those changes and then you have the starts of global change. I think if anything our non-human neighbors out there would tell us, it's this simple truth...change your own life...think better...act more aware of others...think of how your actions effect others...for good or bad and adjust appropriately. Reinforce in your own life positive behaviors and thought processes and minimize the negative and harmful ones. Do that for yourself and then multiply by several billion people.

BTW...I don't think every UFO sighting or abduction story is true, but I think a fair percentage of them are. I've seen things that were not airplanes or helicopters or other human created flying machines on multiple occasions. Many of them are corroborated by others who saw them too. I think alien life is fact, not fiction or a "maybe could happen".

Cool story about your newts. I've never had any critter that lived past it's own generation.
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Re: My excellent adventure through some battery builds

Post by 999zip999 » Dec 23, 2016 10:28 pm

I agree and I want my 7200 what bike for themselves unlocking in my garage with a double locks on the garage door. Plus I keep it Homeless looking, just not too much spit and polish.

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Re: My excellent adventure through some battery builds

Post by Ianhill » Dec 23, 2016 10:58 pm

Astronomers describe our universe as being around 13.8 billion years old, our sun is a third generation star so the first two rounds have been creating lots of heavy elements for complex life to manipulate feed on what ever, Then there's the size factor the stars visible from our planet is estimated at 70000000000000000000000 that's 22 zeros just visable, Anyone who considers this a lonely universe just needs to consider what a light year is and it would take 2.5 million of them just to get out of the milkyway our own galaxy and visit andromeda which is heading towards us so one day in millions of years in the night sky will be light from a galaxy passing through our own and then there is an estimate of 100 billion galaxys so its truly as big as my penis. Theres science out there our brains can not compute for definite planets with some primitive life forms and others life way beyond our own impossible to communicate with and based on completely different level, may have transformed themself's into energy itself for ease of mobility and maintence who knows some the early birds may have had upwards of 10billion years to figure it out.
Whether they have visited who knows dont under estimate the technology of your own government but by no doubt rule it out, one things for sure I bet we are the only ones with Santa ,and the easter bunny. But I bet religion and slavery are spread across the universe not many would have figured out perfect harmony without there being any competition between themself's for whatever reason.

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 24, 2016 6:38 am

Ianhill wrote:Astronomers describe our universe as being around 13.8 billion years old, our sun is a third generation star so the first two rounds have been creating lots of heavy elements for complex life to manipulate feed on what ever, Then there's the size factor the stars visible from our planet is estimated at 70000000000000000000000 that's 22 zeros just visable, Anyone who considers this a lonely universe just needs to consider what a light year is and it would take 2.5 million of them just to get out of the milkyway our own galaxy and visit andromeda which is heading towards us so one day in millions of years in the night sky will be light from a galaxy passing through our own and then there is an estimate of 100 billion galaxys so its truly as big as my penis. Theres science out there our brains can not compute for definite planets with some primitive life forms and others life way beyond our own impossible to communicate with and based on completely different level, may have transformed themself's into energy itself for ease of mobility and maintence who knows some the early birds may have had upwards of 10billion years to figure it out.
Whether they have visited who knows dont under estimate the technology of your own government but by no doubt rule it out, one things for sure I bet we are the only ones with Santa ,and the easter bunny. But I bet religion and slavery are spread across the universe not many would have figured out perfect harmony without there being any competition between themself's for whatever reason.
Yeah...there's lots of space out there and lots of stars and lots of possibilities for possible life forms. Never mind the age of it all...time enough for zillions of possibilities to come about. I seriously doubt all of the races out there have visited our planet, but some of them have...I am convinced. I think as long as there has been life on this planet, there have been visitors here. It's my opinion that life was originated here, not by random chance in some chemical filled pool somewhere or by microbes on a meteor, but rather was planted deliberately by some of our much older neighbors out there. I can't prove it obviously, but it's as logical and probable as is anything else.
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Feb 04, 2017 8:30 pm

I built this tester pack over the last couple of days. I've been wishing I had built something much bigger like this a long while now. This pack can be configured any way from a 6S12P pack to a 36S2P pack. Any combination of 6 cells is possible. Each bank is 6S2P and there are 6 banks. Via the Deans T connectors they can be connected together in parallel or serial how ever I want and I don't need to use all 6 banks. I can use anything from one to 6 banks at a time. It's not intended to be a pack I actually use on an EV...just for testing and charging cells and for using as a bench supply for motor controllers and other EV things. 4.1 volts at 36S is almost 150 volts. My Moped build will be running at 130 volts so this will be useful for that build out at 32S. Laptop cells are only good for 2-3C discharge and that's what will be used in this massive battery holder. Each side holds 36 cells or total of 72 cells. It weighs about 20 pounds fully loaded. The balance cables I had were not long enough to bring them out the end of the pack with the power leads so I had to bring them out the sides...3 per side. It's not ideal and the gap between either side is really wide so it's not useful in an EV. I should have used longer interconnect wires inside, but then the possibilities of creating an internal short would have been significant. AS a result, I can't fold it together all the way. The interconnect wires wont bend together that far. In the pictures I am charging on my dual 6S RC charger. I only had 2P balance cables made up so I could only balance charge four of the 6S banks.

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Re: My excellent adventure through some battery builds

Post by Okami » Feb 04, 2017 8:45 pm

huh looks like you've put a lot of work into this! On what motor / controller are you planning to run these 130v? Seems quite high.. deadly fast.. if you ask me :D I think some cars / motorcycles get to run at such voltages.. a moped would be a formula probably haha

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Feb 05, 2017 10:05 pm

Okami wrote:huh looks like you've put a lot of work into this! On what motor / controller are you planning to run these 130v? Seems quite high.. deadly fast.. if you ask me :D I think some cars / motorcycles get to run at such voltages.. a moped would be a formula probably haha
The motor will be a lightning rods big block. They are rated for 3000 watts, but that's conservative. A few people out there run them at 4000+ watts. Mine is opened up with a blower on it to help keep it cool. I intend to run it at 5000 watts. Voltage is a matter of opinion as to what it's applicable for. Lots of people swear that any EV running at more than 48 volts is excessive. I think, they are wrong. It depends on what you want. If all you want is a 30mph bike, then yeah 48 volts is fine, but if you want a 60mph bike, well that needs lots more voltage. I'm going for lots of speed so I will need to run at 130 volts to get it. There are quite a few controllers out there rated for 150 volts or more so that's not a problem. Mosfets exist that work up to 1000 volts so a controller and mosfets running at whatever I want is quite doable. Cars like the volt or leaf run at waaaaaay higher voltages than 130 volts. A 250cc sized motor cycle could run at 130 volts, but a full sized bike...not likely.
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Re: My excellent adventure through some battery builds

Post by Okami » Feb 06, 2017 4:40 am

Yes, so I somewhat got your point correctly - it is related with speed and possibly amps, too! (higher voltage, lower amps, for the same power output)

I think some of the ''diy'' e-cars uses 100+ volts, high-end motorcycles probably use something way higher but I think some scooters (mopeds) also use about 72v or so. But dont quote me on this, as there were probably somewhat diy builds, too.

----

Mh I should go back to your scooter thread to figure out the speed you are traveling at now.. but I think it was around ~70kph / 43.5 mph?
And that your motor would get quite hot, if you ran the scooter at such speed..

So yep, if yo want to achieve the 60mph, I believe higher wattage motor and higher voltage is really welcome here :) since you have already ''over-clocked'' / overvolted your current motor :)

Anyways, nice that you are sort of like ''pioneer'' here and are pushing the limits of what an e-scooter can do / is capable of.. :D I know a few / some ebikers who can push till about 70-80kph (43.5-50mph) and say that is way too fast and consumes too much Wh / energy to go at that speed, so they dont intend to stay at these speeds anyways, even if their ''hardware/electronics'' allow them to

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Re: My excellent adventure through some battery builds

Post by Ianhill » Feb 06, 2017 11:08 am

Okami wrote:Yes, so I somewhat got your point correctly - it is related with speed and possibly amps, too! (higher voltage, lower amps, for the same power output)

I think some of the ''diy'' e-cars uses 100+ volts, high-end motorcycles probably use something way higher but I think some scooters (mopeds) also use about 72v or so. But dont quote me on this, as there were probably somewhat diy builds, too.

----

Mh I should go back to your scooter thread to figure out the speed you are traveling at now.. but I think it was around ~70kph / 43.5 mph?
And that your motor would get quite hot, if you ran the scooter at such speed..

So yep, if yo want to achieve the 60mph, I believe higher wattage motor and higher voltage is really welcome here :) since you have already ''over-clocked'' / overvolted your current motor :)

Anyways, nice that you are sort of like ''pioneer'' here and are pushing the limits of what an e-scooter can do / is capable of.. :D I know a few / some ebikers who can push till about 70-80kph (43.5-50mph) and say that is way too fast and consumes too much Wh / energy to go at that speed, so they dont intend to stay at these speeds anyways, even if their ''hardware/electronics'' allow them to
If the motor spins up to full speed with no load and does not self destruct with high rpm then the failure point occurs as you start to increase the load, so a heavier rider or steep inclines and gearing. This can be counter acted slightly by using a lighter gearing so you decrease the load to the motor and it uses less amps so it creates less heat but still spins faster.
So to push the motor harder which I intend to do a 24s 100.8v off the charger boma I'll simply gear the motor 6-1 rather than 5-1 and decrease the weight of the ride to as little as possible so I stay within the torque limits of the motor but spin the rotor much faster than stock and reach my 50mph+, I've hit 48mph now on 16s and with my weight i can do a full discharge keeping up with traffic and not have a meltdown, the heat tends to build fast when slippage occurs in the magnetic field to rotor so as long as your aware of this you know if your driving it to hard it will be consuming lots of energy fast so I must watch if I'm pushing a top speed run and I reach an incline I have to back off to a slower speed.

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Re: My excellent adventure through some battery builds

Post by Okami » Feb 06, 2017 1:38 pm

What do you call - magnetic fielf slippage?
the heat tends to build fast when slippage occurs in the magnetic field to rotor



This is something I've never heard of before.. can you tell a bit more about it? The only things I know about overheating the motor.. is that there is a limit on how much heat can it take.. before insulation starts to burn off/melt etc.. There''s less info about loose magnets and all of that.. besides the story that heat kills magnets but I assume that the magnets in motor should be of ''higher temperature'' grade.. not to loose their magnetic properties easly..

---

What you describe with decreasing the load for the motor sounds good.. I think at some point we will have to ''invent'' gearing system for some of the electrical motors, so they stay in their ''comfort zone'' a bit more..

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Re: My excellent adventure through some battery builds

Post by Ianhill » Feb 06, 2017 1:57 pm

Okami wrote:What do you call - magnetic fielf slippage?
the heat tends to build fast when slippage occurs in the magnetic field to rotor



This is something I've never heard of before.. can you tell a bit more about it? The only things I know about overheating the motor.. is that there is a limit on how much heat can it take.. before insulation starts to burn off/melt etc.. There''s less info about loose magnets and all of that.. besides the story that heat kills magnets but I assume that the magnets in motor should be of ''higher temperature'' grade.. not to loose their magnetic properties easly..

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What you describe with decreasing the load for the motor sounds good.. I think at some point we will have to ''invent'' gearing system for some of the electrical motors, so they stay in their ''comfort zone'' a bit more..
Sorry I did not make sence by there and I'm by no means an expert but I have been through a few text books in my time so I not a amateur either.
Slippage would be a rotor that lags behind the magnetic field of the stator, the boma is a synchronous motor so it should never slip as such but it can encounter its torque limit then the phase pulses will be on for longer durations till the rotor makes a turn or if stalls the phase will melt out. So this tends to occurs at heavy load starts or pushing high speeds so the magnetic field interaction is not strong enough to create the torque needed to spin faster or start in the first place.

Combustion cars need gears because their torque band is narrow an electric motor provides full torque 0-max rpm more or less so any gears are not needed really and add weight and more inefficiency. Its only the final ratio that needs to be played with on electric.

I know I'll be fighting the stock heat dissipation the motor has but I've got a few trick up my sleeve to keep its temp with in range I may rewind the motor I've been threatening it for a long time now but I'll do a no load test when I have the controller to see what figures I got and go from there.

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