My excellent adventure through some battery builds

Batteries, Chargers, and Battery Management Systems.
User avatar
Okami
100 mW
100 mW
Posts: 46
Joined: Jun 02, 2016 3:00 am

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!

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
Okami
100 mW
100 mW
Posts: 46
Joined: Jun 02, 2016 3:00 am

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)

User avatar
Ecyclist
100 W
100 W
Posts: 272
Joined: Apr 01, 2016 10:53 pm
Location: San Diego, California

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.

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
Ecyclist
100 W
100 W
Posts: 272
Joined: Apr 01, 2016 10:53 pm
Location: San Diego, California

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

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
Ecyclist
100 W
100 W
Posts: 272
Joined: Apr 01, 2016 10:53 pm
Location: San Diego, California

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.

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.

Image
Image
Image
Image
Image

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

Image
Image
Image
Last edited by ElectricGod on Aug 31, 2017 12:53 am, edited 1 time in total.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.

Image

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

Image

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

Image
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
Okami
100 mW
100 mW
Posts: 46
Joined: Jun 02, 2016 3:00 am

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.

Philaphlous
100 W
100 W
Posts: 183
Joined: Mar 28, 2017 7:17 am

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.

User avatar
Ecyclist
100 W
100 W
Posts: 272
Joined: Apr 01, 2016 10:53 pm
Location: San Diego, California

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 :?:

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.

Image
Image
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
amberwolf
100 GW
100 GW
Posts: 25062
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

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.

Ianhill
100 kW
100 kW
Posts: 1179
Joined: Sep 25, 2015 5:55 pm
Location: Wales UK

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 ?

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

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.

Image

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?
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

INR21700-48G testing

Post by ElectricGod » Feb 09, 2018 11:30 pm

My final conclusion is that the INR21700-48G cell is not very compelling.

The best I saw was 4400mah and more often 4200mah. That's soooooo not 4800mah! Disappointing is what I call that!
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

RMartin EVD battery builds

Post by ElectricGod » Feb 09, 2018 11:36 pm

I've been putting together batteries for the RMartin.

I had ten 10,000 mah LIPO packs which is 2 short of making a 3 16S packs so I bought a couple more to make this 30Ah pack. There's 3 banks of 16S and they each get their own BMS. I had 2 identical 16S BMS and one from another source. I've bought another 16S BMS for another 10,000 mah pack to make 50Ah of LIPO.

Image

Image

Image

Image

Image

Partly into building the 30Ah pack, I thought it looked really close to the same size as a 50Ah SLA. Sure enough, they weigh almost the same amount too. Except that it's 30Ah at 66 volts as compared to 50Ah at 12 volts or 3.3X more capacity than the SLA at the same weight.

Image

Image

I also have 26 LTO cells which is enough for 66 volts. I'm still waiting for hardware to arrive for screwing the tabs together and I'm getting super cap protection boards to protect the LTO cells from charging over 2.7 volts. I'm toying with the idea of going with LTO's for the entire 131 volt pack. They are heavier than any other lithium solution and have less capacity, but they also don't have problems with the cold, are 50% the cost of Multistar packs per Ah and have about 10,000 charge cycles. They don't need a BMS either. This could be very compelling despite the weight and size.

Image

All of this will go into the RMartin at 66 volts for now until I have the electrical mods done and am ready to move to 32S or 131 volts. It's about 62Ah total.

Image

There's also 8 16,000mah LIPO packs that I might put in the Martin for a while. The idea is use what I have now and slowly build out the permanent pack as I have money for more batteries. All of these LIPO's can be reconfigured however I want. Right now they are "testing" a 24S smart BMS.

Image

Image

Image
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
Okami
100 mW
100 mW
Posts: 46
Joined: Jun 02, 2016 3:00 am

Re: My excellent adventure through some battery builds

Post by Okami » Feb 23, 2018 7:56 am

Looking good. Looks like you are progressing battery wise..

Would be interesting to find out how much the final weight is for your scooter with different battery configuration. As you said lifepo will be heavier but how much more?

miro13car
100 kW
100 kW
Posts: 1462
Joined: Mar 26, 2007 1:30 pm
Location: Calgary, Canada

Re: My excellent adventure through some battery builds

Post by miro13car » Feb 23, 2018 9:28 am

using battery holders for interconnection?
what about contact resistance?

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

Re: My excellent adventure through some battery builds

Post by ElectricGod » Feb 27, 2018 12:02 pm

miro13car wrote:
Feb 23, 2018 9:28 am
using battery holders for interconnection?
what about contact resistance?
They are used laptop cells. Contact resistance is the least of my concerns! The cells can have widely varying Ir and capacities. That's the point of the battery holders...easy swapping out of cells. I don't want to weld them up into packs considering they are used laptop cells. For other purposes, such as cell testing, a battery holder is imminently useful.
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

32S, 300 amp, BT, LCD BMS quicky review

Post by ElectricGod » Feb 27, 2018 3:59 pm

I got 2 of these smart BMS in 32S, 300 amp version. I have had no time to power them up yet, just take one apart and take pictures and look up a few parts. It's essentially the big brother to the 24S LCD smart BMS. The below picture is the 24S version powered up. I have one of those too. The 32S version looks effectively the same...just a little larger. I have 8 LIPO packs that will be put together into a 32S pack for testing the BMS. I won't be able to deliver 300 amps to the BMS...more like 100 amps max, but I can at least bench test.

Image

The balance board is decently made with dual CPU's on it. One is an atmel 328 and the other is a smaller 8 bit atmel cpu. The board has a dedicated DC-DC converter and opto isolators protect the LCD, balance board and mosfet boards from each other. Cell balancing typically is done with chemistry specific IC's. These BMS use a different method. They are highly flexible and can balance any battery chemistry. As a result typical LION IC's would NOT work here. They chose to use 74HC595 latches instead. They remember their last state and essentially turn on and off the mosfets that do the balancing. All BMS do this in some fashion. Cell monitoring happens in the CPU, not in the chemistry specific IC's. The atmel 328 tells which latch to turn on or off for balancing. This allows the BMS to balance at 1 volt or 4.5 volts per cell or whatever is meaningful to you and has been set in the software. This design completely eliminates the need for a LIFE or LION or LTO or SLA or whatever. There is no need for a chemistry specific BMS, just set it to the parameters of your cell chemistry and you are done.

Image
Image

There's no access to the P- connection. Same for the 24S version. I'll have to get longer screws so that I can add copper on top of the mosfet tabs to add P-. Grrr! All you get at those solder tabs is B- and C-...what a waste. If you don't mod the BMS, you have to charge and discharge via C-...I'll pass! There is no good reason EVER to discharge via C-. C- is for Charging, not for discharging (P-). The copper reinforcing is done well, solders to each mosfet and over laps the wire bond pads.

Image
Image
Image

This is truly confounding! This is a 32S BMS. That means it realistically needs to handle upwards of 140 volts depending on cell chemistry. So why does it have 100 volt mosfets (HY45N10's) on the C- side? Why no access to P- where it has 150 volt IRF4115's? There is no part of 100 volt mosfets that are OK in a 32S BMS designed for 140 volt continuous operation. I can't imagine what the manufacturer was thinking!

Image
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

User avatar
ElectricGod
1 MW
1 MW
Posts: 1656
Joined: Nov 01, 2015 5:24 pm

24S, 200 amp, BT, LCD BMS quicky review

Post by ElectricGod » Feb 27, 2018 4:15 pm

I got this 24S BMS a few weeks ago. Initial set up so it would charge and discharge took a few minutes to figure out, but otherwise it was pretty straight forward to set up for someone who knows what they are doing. The BMS won't charge if you have the pack OVP set lower than the actual pack voltage. It also won't discharge if pack LVC is set higher than current pack voltage. The BMS can't know what are "normal settings" since it's wide open to setting changes... how ever you set them...correctly or not. You can make setting changes that create conflicts and the software deals them by NOT letting you charge or discharge under certain circumstances. Be smarter than the BMS.

These BMS includes a tiny button that allows you to turn it on or off. It makes for an easy way to cut all power in and out of your EV. There's no need to disconnect the battery for long storage events, just press the button until the BMS shuts off.

WARNING!!!
These are highly flexible and adjustable BMS. They can't know you have LIFE chemistry connected to it and then in settings you have HVC set to 4.5 volts. It's going to try and charge each cell to 4.5 volts. Miss-charging lithium batteries tends to be VERY bad!!! This is NOT a beginners BMS. If you can't intelligently make good choices for the settings, then get a dumb BMS that makes all the choices for you. If you make incorrect settings, the BMS will try to follow them...regardless of the end results...fire, cell damage, good operation, whatever.

These BMS have a brilliant feature IMHO. They are battery chemistry agnostic. You enter in the setup program the specifics for your cell type and then it balance charges and discharges according to those settings. For example, LTO can go dead flat to zero volts without harm and charges to full at 2.8 volts. This BMS will allow you to set LVC to 0v and HVC to 2.8 volts for LTO. HV LIPO wants 3 volts as it's LVC and 4.36 volts for HVC. Set it in the BMS and you are good to go. LIFE wants 3v for LVC and 3.6v for HVC...set it and you are done. HVC can be set as high as 4.5 volts. Like I said...chemistry agnostic. This is brilliant but dangerous functionality! The BMS has BT and an android application that does everything you need to set up, monitor and use the smart BMS. See the below screen shots of the app. There is one exception which is odd. You can't see anything like this in the android app. It's not for lack of data incoming from the BMS either.

Image

So then the actual BMS. Nothing new here...posted this pic already.

Image

The B- connection with a 5.5mm bullet added by me.

Image

This bullet is soldered to C- which is for charging, NOT for discharging. The unused pad behind it is P-. That's what you power your EV from, NOT C-. I'll get to my gripes about P- shortly.

Image

Heatsinks...

Image

This is one of the areas that these BMS are really strong...mostly. The copper reinforcing is well done and securely soldered to every mosfet for best heat and current transfer. However, the middle buss is P- and for whatever dumb reason has no copper on it at all. This is a big oversight since you want to power your EV from P-. I will be adding copper here as soon as the longer M3 screws arrive. Grrr!

Image

This BMS comes in several current ratings. This is the 200 amp version and as a result not all the mosfet positions are filled. It uses the MDP1991 100 volt mosfet which is decent. To get the 300 amp version uses a better mosfet and all positions filled. It also has 2 rows of copper at C- and B- and still nothing at P-...go figure! They do this so that when soldering down the P- buss, they don't have to deal with solder leaking through the board and messing up the flat surface that the mosfets need to sit on. Tha't fine, don't solder it down, just put the copper UNDER all the screws (same difference) and then solder to the P- pad only.

Image

This is the brains of the BMS. There's an atmel 328 running the show, BT module and various support IC's.

Image

This side of the balance board is mostly balancing components. I'm not dead sure, but I believe those resistors are 3-5 watts each. This thing can run down an over charged cell at something like an amp at least. The resistors have a heat path to the heat sink cover. In most BMS, you get something like 300mA at most. Discharge rates for balancing can be set in the app.

Image

The LCD.... IT has 2 buttons, but they do not set the BMS in any way. They are merely up and down and LCD power only.

I live in the USA where MPH is still used. Unfortunately you can't change the speed to MPH or temps to Farenheit. Honestly though, I will never look at the BMS to tell me my speed, just to tell me battery status. I took all these pictures moments after connecting up a 24S pack. The settings have not been set yet so the BMS has no clue what anything is yet. This is the default page that the LCD displays when it powers up.

Image

Maybe someone that can read squiggly can tell me what these say? I would have preferred all the screens be in English, but no one asked me (I'm really crushed! No really, life is OVER. I will never recover. No seriously...life is really over. I will now go into a deep funk and never get better....for the next 10ns). Supposedly there is an English version of the balance board that corrects this. What I don't get is there is plenty of English elsewhere, why not on these pages?

Image
Image
Image

This one of those things that I'd like to have control over. This page is all about battery and BMS status and nothing about EV speed. Why can't this page be the default page on the LCD. You have to select up or down several times to get here.

Image

Cell voltages. Minor oversight since this is a 24S BMS, not a 32S BMS. At least cells 25-32 don't show any voltage!

Image
Image

Finally, some pictures of the android app. This is the home screen or "MainView". I'll get back to this later.

Image

Param 1....lots and lots and lots of settings for anything you can imagine. Be careful!!!

Image
Image
Image
Image

Param 2 is more of a status page. There's no settings here...thank god! I'll show this later in MainView, but you can turn off/on the charge and discharge mosfets...as seen here. This is a great way to disable your EV or to cut power without the need for a contactor. It really works...or at least does on the bench. I'll try it for real later.

Image
Image

There is also this log page (SysLog button on MainView). It lists charges, discharges, run times and so on. It's history and NOT current events like Param 2.

Image

I didn't want to get lost in the MainView details until I had shown the rest of the screens. There's LOTS here! It does a running log of BMS update and change events in the large pane. I'd prefer if everything was in English, like all the rest of the pages in the app, but this is a firmware issue with the supposedly non-English balance board.

1. The Visible button makes your phone visible to other BT devices so that discovery can happen. It's an odd option since you really need to go to BT settings in android and find the BMS and pair to it from there before you can do anything else.
2. Connect does exactly that, It lets you select what BMS the app is connecting to. This is NOT BT pairing. I have 3 of this style BMS. I'm grateful for this feature so I know what BMS I am connecting to!
3. Syslog gets you to the running historical log.
4. Since the BT pairing password is 1234, please set a password so some random person can't hack your BMS.
5. LI-ION and FE-LI param do pretty much the same thing. They set the BMS to the parameters needed for those chemistries. I went into Param 1 and changed them to what I wanted, but it was a good starting place.
6. Modify BT address lets you name the BMS to something meaningful for discovery and later reference. Mine is still defaults, but I'll probably name this one 24S200A. BMS-ANT doesn't really mean anything to me.
7. Reboot does exactly that. I had an issue with BT not connecting correctly. Reboot got BT working again. There's no OS on these BMS, but you can use this option to get it to reinitialize itself.
8. Charge on/off and Discharge on/off set the states of the C- or P- mosfets. This is where you can disable the BMS outputs...sort of like a contactor. Let's say you charge at C- and then want to disable the battery charge port so that a random person can't put a paper clip across your charger port and create a giant spark, select Charge Off. Later on select Charge On so you can charge again. Discharge on/off is like your main battery contactor. The EV is not going anywhere without this on.
9. Completely screw up the settings or changed something by accident, just hit Factory Reset and start over again.
10. I have no idea what Flip Screens does.
11. Auto Equalization allows you to turn off balancing. I don't know why you would do this, but you can. IMHO balancing is the primary function of a BMS. Everything else is secondary. Param 1 has settings that effect this option and general balancing.
12. Current Zeroing allows you to adjust the current reading of the BMS. Not all shunts work identically, not all current sensing works identically and sometimes they can be off. This allows you to set it accurately if needed.
13. MainView, Param 1 and Param 2 let you select the 3 main pages in the app.

Image
ElectricGod...it's a joke...don't take things so seriously folks!

XB-502 Moped:
https://endless-sphere.com/forums/viewt ... 0#p1222730

Currie scooter:
https://endless-sphere.com/forums/viewt ... 7#p1227407

Post Reply