My excellent adventure through some battery builds

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

Post by Okami » Feb 06, 2017 3:47 pm

Now I sort of understand it better.. high speed or high load does seem logical to cause ''problems''. In simple terms (my understanding) the motion/spinning shaft just cannot keep up with the magnetic force which is making it rotate.. so the force has to ''go elsewhere'' - (heat probably/perhaps?) or it just makes it stall / starts to cause some other problems like you said..

Btw - I tried to push hard my board today with turned off motor/esc.. and it started braking (show resistance).. im really glad I did not fry something.. as I just remembered that some currents are generated which might not be that good for the esc.. I always used to push with board turned on.. but this time because my battery got really low I turned off the board to ''let the batteries bounce up''.. which might not have been a that great idea to do in the first place.. Will probably try to remember this and tell to other folks not to run their board with turned off battery power, while they are still connected to the esc!

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Feb 13, 2017 9:43 pm

Okami wrote:Now I sort of understand it better.. high speed or high load does seem logical to cause ''problems''. In simple terms (my understanding) the motion/spinning shaft just cannot keep up with the magnetic force which is making it rotate.. so the force has to ''go elsewhere'' - (heat probably/perhaps?) or it just makes it stall / starts to cause some other problems like you said..

Btw - I tried to push hard my board today with turned off motor/esc.. and it started braking (show resistance).. im really glad I did not fry something.. as I just remembered that some currents are generated which might not be that good for the esc.. I always used to push with board turned on.. but this time because my battery got really low I turned off the board to ''let the batteries bounce up''.. which might not have been a that great idea to do in the first place.. Will probably try to remember this and tell to other folks not to run their board with turned off battery power, while they are still connected to the esc!
Riding your board with the controller turned off is not a big deal. The mosfets will be off so the resistance you feel is all in the motors. If your controller supports regen, I would tell you to kick along and use regen to "charge your batteries". When you let off the throttle at whatever speed and you are just coasting, the motor is acting like a generator. With no regen capability, those pulses of free electricity are going no where. With regen, they get back to the battery instead.

Bouncing back...LOL...don't do that. As you know, your batteries will recover some of their voltage if you let them rest. Where do you suppose those magical electrons come from? They were already in the battery, just further away from the electrodes and so they were inaccessible for work until they migrated towards the battery poles. You can get the same effect with an alkaline cell or car battery...or any kind of battery. That momentary recovery is only paper thin and then it's gone. The reason why I say don't do that is by then your batteries are already depleted and all you are doing is running them too low and causing damage to the battery pack. Batteries are expensive. Make them last as long as possible.
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Re: My excellent adventure through some battery builds

Post by Okami » Feb 14, 2017 4:34 am

Yeah, I usually dont run them down that much! This was more ''for the science'' than for everyday use.

Just ppl didnt believe that I should stop discharging below 3.45 no load voltage.. As basically, there is about 100mah left below that anyways per cell, which isnt very useful as it is not ''easly obtainable'' anyways..

Well, the thing is, that my battery was disconnected in the event of ''kick-pushing'', I dont know how the circuit got completed exactly but this is how it was connected:

Main Turn on/off switch -> Wattmeter -> Esc - > Motor.

Esc's switch (smart one) is always turned to on.

--
So basically, the last thing in the chain was Wattmeter im not sure does my car esc really support regen as I've had it shut-off a few times when I tried to brake hard.. it did not completely shut-off, it just stopped responding to the inputs from the remote while its fan was still spinning and lights being turned off

Anyways.. it was an odd / strange experience to see the motor stall a bit (for whatever reason) while kick-pushing.. and actually one other time when I did not push so hard but also forgot it is bad to kick-push with everything turned-off, the Wattmeters display lit up a bit.. at least it looked that way.. which was also strange enough

Ok, so enough rant about Regen braking with main battery turned off but non the less, it was a bit weird both times that the motor started to stall (no place for current to go? and the second time wattmeter's display came alive for a few seconds.. (not sure what it showed)

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Re: My excellent adventure through some battery builds

Post by Ecyclist » Feb 19, 2017 12:27 pm

ElectricGod thank you for sharing your knowledge.
I'm planning to build a battery pack similar to yours. Before I read your post I had some reservations, but not anymore.
I would like to take my e-bike overseas. I can't take batteries with me, so I will build a reloadable case.
I will just buy cells at the destination, put them in, and I will be on my way exploring Japan.

Can you recommend BMS for 13s4p li-ion battery pack?

BTW: I also like your WYE-DELTA project and I'm very impressed with the way you handle negativity from others.
Persistence is a key to success. Enjoy your journey. That's what life is all about.

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Feb 21, 2017 5:10 am

Ecyclist wrote:ElectricGod thank you for sharing your knowledge.
I'm planning to build a battery pack similar to yours. Before I read your post I had some reservations, but not anymore.
I would like to take my e-bike overseas. I can't take batteries with me, so I will build a reloadable case.
I will just buy cells at the destination, put them in, and I will be on my way exploring Japan.

Can you recommend BMS for 13s4p li-ion battery pack?

BTW: I also like your WYE-DELTA project and I'm very impressed with the way you handle negativity from others.
Persistence is a key to success. Enjoy your journey. That's what life is all about.

Thanks for the compliments. WYE/delta switching isn't a bust, but switching my inrunner is a bust. It drinks current in delta. Maybe other motors will switch over better. Back EMF in my big block kills its performance in delta. I'll try this again on some other motor later. People tell me "no you can't do that" and then don't offer good reasons why or just express negativity. Well that just makes me more likely to ignore them and do it anyway. Worst case I blow something up and learn things along the way. All good!

What amp draw do you need in a BMS? Just about any BMS will work with less than all of it's channels used. It's not uncommon to get say a 20S BMS and use only 18S or 16S on it. On a battery holder built pack the interconnects can be a bit tricky between the two sides. I made foldable interconnects. That's basically a piece of solid copper wire with a bend in the middle that will collapse in a specific direction. Also secure the cells so they can't vibrate loose from their holders. This is simple to do. Just eliminate any gaps between the packs and the battery box walls and the packs. Have fun in Japan.
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Re: My excellent adventure through some battery builds

Post by Ecyclist » Feb 21, 2017 9:23 pm

I thought that negativity and lack of positive feedback were reserved only for me. I read posts from 2010 and I can tell you that this forum was a different place 7 years ago. I posted a question in your thread about "Adding halls to an Astro Flight 3220 inrunner" and received two replies. 1) not on topic, 2) will not find a motor for that price. When I pointed out that 1) I'm asking about controller used in relation to this topic and 2) I already found one motor like that, I've gotten crickets so far. This seems to be a norm nowadays.
So, I really appreciate your reply and kindness.
I read on your post that you didn't like the BMS that you used on your first battery pack, so I thought that you found a better BMS that you can recommend. My plan is to use 30A for starters and 50A in the future. I have a little over 100 Tesla batteries that I'm planning to use to test the concept.
Also, I discovered today that the used GNG motor that I bought from ES member is overheating when running for 5 min. with no load.
Obviously, something is wrong with that motor.
I'm wondering if you could recommend an easy way to pinpoint the problem. I have a multi-meter and access to an oscilloscope.
I also have a perfectly working motor in the kit that I have on my bike. Worst case scenario, I will take both motors apart, swap the part and find the problem. Kind of a long process but doable.
Thank you,
Les

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Feb 22, 2017 9:23 pm

Ecyclist wrote:I thought that negativity and lack of positive feedback were reserved only for me. I read posts from 2010 and I can tell you that this forum was a different place 7 years ago. I posted a question in your thread about "Adding halls to an Astro Flight 3220 inrunner" and received two replies. 1) not on topic, 2) will not find a motor for that price. When I pointed out that 1) I'm asking about controller used in relation to this topic and 2) I already found one motor like that, I've gotten crickets so far. This seems to be a norm nowadays.
So, I really appreciate your reply and kindness.
I read on your post that you didn't like the BMS that you used on your first battery pack, so I thought that you found a better BMS that you can recommend. My plan is to use 30A for starters and 50A in the future. I have a little over 100 Tesla batteries that I'm planning to use to test the concept.
Also, I discovered today that the used GNG motor that I bought from ES member is overheating when running for 5 min. with no load.
Obviously, something is wrong with that motor.
I'm wondering if you could recommend an easy way to pinpoint the problem. I have a multi-meter and access to an oscilloscope.
I also have a perfectly working motor in the kit that I have on my bike. Worst case scenario, I will take both motors apart, swap the part and find the problem. Kind of a long process but doable.
Thank you,
Les
This is a good BMS for the price.
http://www.ebay.com/itm/112290923316?_t ... EBIDX%3AIT

Your motor questions belong elsewhere, not a battery thread in the battery section of ES.
Last edited by ElectricGod on Feb 22, 2017 9:51 pm, edited 1 time in total.
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Re: My excellent adventure through some battery builds

Post by Ecyclist » Feb 22, 2017 9:37 pm

ElectricGod wrote:
Ecyclist wrote:I thought that negativity and lack of positive feedback were reserved only for me. I read posts from 2010 and I can tell you that this forum was a different place 7 years ago. I posted a question in your thread about "Adding halls to an Astro Flight 3220 inrunner" and received two replies. 1) not on topic, 2) will not find a motor for that price. When I pointed out that 1) I'm asking about controller used in relation to this topic and 2) I already found one motor like that, I've gotten crickets so far. This seems to be a norm nowadays.
So, I really appreciate your reply and kindness.
I read on your post that you didn't like the BMS that you used on your first battery pack, so I thought that you found a better BMS that you can recommend. My plan is to use 30A for starters and 50A in the future. I have a little over 100 Tesla batteries that I'm planning to use to test the concept.
Also, I discovered today that the used GNG motor that I bought from ES member is overheating when running for 5 min. with no load.
Obviously, something is wrong with that motor.
I'm wondering if you could recommend an easy way to pinpoint the problem. I have a multi-meter and access to an oscilloscope.
I also have a perfectly working motor in the kit that I have on my bike. Worst case scenario, I will take both motors apart, swap the part and find the problem. Kind of a long process but doable.
Thank you,
Les
This is a good BMS for the price.
http://www.ebay.com/itm/112290923316?_t ... EBIDX%3AIT

Your motor questions belong elsewhere, not a battery thread.
Thank you.

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ElectricGod
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Aug 30, 2017 7:29 pm

More batteries built...

32000mah x 20S or 82 volts and dual 80 amp BMS or 160 amps max.

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Two 10,000mah LIPO packs at 16S or 66.5 volts and 50 amp BMS

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Last edited by ElectricGod on Aug 31, 2017 12:53 am, edited 1 time in total.
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Aug 31, 2017 12:51 am

More pack builds...

12S, 48 volt, 8000mah with 30 amp BMS.

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16S, 66 volt, 8000mah with 50 amp BMS.

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16S, 66 volt, 10,000mah with 50 amp BMS.

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Re: My excellent adventure through some battery builds

Post by Okami » Sep 20, 2017 6:26 am

Nice big packs.. Interesting to see such widespread use / coverage of kepton tape.. :) Im not sure whenever I would wrap my packs like that, though I know it is good for heat insulation.

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Re: My excellent adventure through some battery builds

Post by Philaphlous » Sep 20, 2017 2:09 pm

Wow what a great thread! Similar to my pack I built using mostly new and a few used laptop battery packs. I have a few brand name cells thrown in there from used laptop packs where I tested the cells and used ones that got at least 2000mah. The 13s7p pack is hefty but actually quite small once it's on the bike. I have it velcro'ed to the top rail and it's entirely removable for charging and balancing. I did all 13 series separate with deans connectors so I can check and balance if needed. All in all its 91 cells of soldered glory. Used a crap ton of solder wick wire for my cell attachments and even more hot glue. Wrapped the entire battery up in gorilla glue tape and it's all set. Charged it about a dozen times now with over 120miles on the bike. Works amazing! I'm self limited to about 1400w since I'm a bit leary of going over that for I have no idea the real discharge capacity of the cells I'm using. The bike holds up great with steel dropouts and can easily charge up hills pulling 1300w consistently. The battery pack does get warm after a 10 mile ride but I think some of that is also due to my knee being right up against the side of the battery pack.

One of the most fun things I've ever built. Absolutely love taking the bike on Sunday mornings and taring up the city parking lots and neighborhoods. Super careful riding around cars tho...especially in my area. People are clueless. Lol

Wish now I would have made a 72v battery or at least 54v but hey...I made the best with what I had.

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Re: My excellent adventure through some battery builds

Post by Ecyclist » Sep 21, 2017 8:22 pm

Would it be electrically and electronically sound to move capacitors inside the battery case and put the power switch between the controller and capacitors? This way I wouldn't have to worry about the pre-charge switch because capacitors would be connected to the battery pack in a semi-permanent way. :idea: What do you think :?:

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 30, 2017 4:45 pm

Ecyclist wrote:
Sep 21, 2017 8:22 pm
Would it be electrically and electronically sound to move capacitors inside the battery case and put the power switch between the controller and capacitors? This way I wouldn't have to worry about the pre-charge switch because capacitors would be connected to the battery pack in a semi-permanent way. :idea: What do you think :?:
That doesn't deal with the caps in the motor controller and that's specifically what you need to do precharging for.
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Re: My excellent adventure through some battery builds

Post by ElectricGod » Dec 30, 2017 4:47 pm

40 INR21700-48G cells arrived today. They will be made into a 20S2P pack.

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Re: My excellent adventure through some battery builds

Post by amberwolf » Jan 01, 2018 12:03 am

ElectricGod wrote:
Dec 30, 2017 4:45 pm
Ecyclist wrote:
Sep 21, 2017 8:22 pm
Would it be electrically and electronically sound to move capacitors inside the battery case and put the power switch between the controller and capacitors? This way I wouldn't have to worry about the pre-charge switch because capacitors would be connected to the battery pack in a semi-permanent way. :idea: What do you think :?:
That doesn't deal with the caps in the motor controller and that's specifically what you need to do precharging for.
Plus capacitors have some leakage current, which while low, could slowly drain a pack over time if left sitting and not checked or charged.

Or worse, if a cap fails internally shorted (rare, but it's happened in a number of devices I've had to repair for the problem), the battery pack will be able to discharge it's full current thru it with nothing to stop it (no fuse, no switch, etc), and if nothing stops the current then you could have a fire.


If you move the caps *out* of the controller to the battery pack, then they don't do what the controller needs them for, and the controller will then see large transients in voltage as currents thru the controller change from motor demands.

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Re: My excellent adventure through some battery builds

Post by Ianhill » Jan 01, 2018 4:22 pm

Caps are good for smoothing out big inductive spikes like a florescent light start up but with a motor running from battery source the caps will give an instant boost in available power only if the battery cannot match the controllers demands and in that case it's better to add more cells than caps on the input side of things as it's just direct dc no fast switching.

Could there be any difference it two systems side by side caps vs battery's on throttle response ?
How instant can each do work ?

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Re: My excellent adventure through some battery builds

Post by ElectricGod » Jan 10, 2018 11:18 pm

Adding from the INR21700 thread...

Hi folks...

There are several advantages that this larger case provides.

1. The cells pack together a bit better than 18650's. This means more total capacity in the same amount of space.
2. The greater cell capacity was significant. I've been using 18650's and LIPO for a good while and really wanted a cell that would have lots of capacity per cell that wasn't LIPO.

To date, I have been testing on my SkyRC D100 charger and a 6S 21700 battery holder I made.

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Cell specs say full charge at 4.2 volts and discharged at 2.5 volts. Everything I've ever known about LION before says fully charged is 4.1 volts and discharged at 2.75 volts. Did something change that I'm not aware of?

I tested the cells soon after their arrival and they were all at 3.58 volts. I then charged them to full (4.1 volts) and recorded their capacities. All cells came in at around 3400 mah. Some had a bit more capacity.

My SkyRC D100 charger doesn't go lower than 2.9 volts and these cells are rated down to 2.5 volts. I'm not really testing them to full capacity when I do a discharge test. My results so far are a bit skewed as a result since I'm not going down to 2.5 volts or up to 4.2 volts. So far I see 3600mah down to 2.9 volts. They are rated at 4800mah so that means that between 2.5 volts and 2.9 volts and above 4.1 volts is another 1200mah that so far I am not measuring. I'm skeptical, but we will see. My next round of testing will be at 4.2 volts.

My experience with any battery pack is that the closer to discharged you get the more sag you experience. My expectation is that these cells at below 2.9 volts are going to sag a good bit. My D100 discharges at 400mA which is not a load test, just a capacity test. I have 35 halogen bulbs I've used for load testing many times. Each bulb is 12v, 55w, 4.6 amps. 2 of these bulbs in series will be pretty close to a 1C load on the 6S pack. I'll put a watt meter in between the pack and the load to measure Ah and a cell monitor on the balance lead to measure individual cells.

I have checked 12-15 cells to determine their Ir. Most are in the 35-38 milli ohm range and a few as high as 43 milli ohms. This seems somewhat disappointing, but everything I've read elsewhere shows this is a typical Ir for this cell. However, it may be that these cells don't increase their Ir like most cells do as they age. In that case 35-38 milli ohms isn't that bad. Very rarely do people scrutinize their packs individual cells after they are 6 months old or older. It is common for cells to creep up to 40 milli ohms or higher in that time frame.

Future LION development is coming. Supposedly 6000mah capacity in the 21700 is coming soon. Maybe wait until we see capacities over 5000mah before buying? I ran into a deal on what are supposedly Samsung cells rewrapped to be generic and are rated at 5000mah. I didn't buy them. If Samsung won't at least put their name on the wrapper, why should I trust them?
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