Custom E-Bike battery issues

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Ok so after knocking off the old 10x2400mah mismatch cells, now I can't get the 10s2p configuration to work with the new cells.

After some troubleshooting seems like the BMS failed once again! Spoke to the vendor who says its in standby mode 🙄. Returning the BMS to the vendor. Please watch the video of my troubleshooting for more information.

BMS troubleshooting

I did try charging the battery pack as advised, but that didn't work.

Some noob tips to disassemble the kit:

1. You can use a tire lever(fiber) to lift the end caps and pop them out safely without the fear of shorting.

2. A heat resistant tape works fine to hold the contacts while testing the incomplete battery pack.
If I were you I would start from the beginning. My experience in general when something is put together and taken apart several times to troubleshoot it can create new problems on its own.. Like bad connections.
I would measure each cell for resistance and voltage and charge each individually to its nominal voltage of 3.60v

Samsung 18650-35E Data Sheet

8.5. Mixing use
8.5.1. Different types of cell, or same types but different manufacturer's cell
may lead to cell rupture or damage to system due to the different
characteristics of cell.
 
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Sierratim

Well-Known Member
Region
USA
City
Nevada City, CA & Paradise Valley, AZ
If I were you I would start from the beginning. My experience in general when something is put together and taken apart several times to troubleshoot it can create new problems on its own.. Like bad connections.
I would measure each cell for resistance and voltage and charge each individually to its nominal voltage of 3.60v

Samsung 18650-35E Data Sheet

8.5. Mixing use
8.5.1. Different types of cell, or same types but different manufacturer's cell
may lead to cell rupture or damage to system due to the different
characteristics of cell.
Good advice from a major manufacturer.

I also like the Drop Test pass-fail criteria in the first section (pg 6);

"Criteria: No fire, no explosion." 😱

These are high energy cells that perform well when treated gently. If not, they can become dangerous very quickly.
 

ebikerxx

New Member
Region
Asia
Yes, will check for internal resistance this time around even if they are from the same manufacturer, since I have no idea if all of them are from the same lot. Battery technology is advancing rapidly, so it makes sense to verify all the parameters before connecting them.

As for buying from the big 4 battery companies, I would love to, if I could afford them. Same goes for a smart bluetooth BMS. I have a 2 amp with no display, hence a balance charger would be a worthy investment to build battery packs.

As for using cells with different capacities, I found this helpful:

https://endless-sphere.com/forums/viewtopic.php?t=75779#p1144385

One of the posters mentions that LVD is a major concern, and advises to use a per-cellgroup-parallel connection for BMS, not sure what that configuration looks like.

Overall, I understand the best practices to be followed, and the dangers of hacking a battery pack. In fact I'm going to make a check-list and a workflow, so I don't mess up the next time around.

Oh well, got my e-bike moving with my first DIY battery pack, so that counts for something. Let me disassemble and then rebuild the pack. But I'm pretty sure that the BMS is knocked out.

Thanks for all the suggestions and feedback. Much appreciated!
 
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Art Deco

Well-Known Member
Region
USA
City
Selinsgrove Pennsylvania
Seems like learning how to rebuild the part of an ebike that is the most expensive and has the shortest usefull life of all the major components of an ebike is a very usefull skillset. But quick advancement in this technology may mean lots of time spent just trying to keep up. Improved BMS and cell chemistry is always RSN .. real soon now. :cool:
 

tomjasz

Well-Known Member
As for using cells with different capacities, I found this helpful:
DrkAngel thread is what I used for my foray into salvage cells. However, I found new old stock of 18650 battery modules. Stripped them, tested, rewrapped and after reviewing the time spent I never built again. I will build my own from new matched cells this spring if I need a battery.
2ED3A892-EDDD-4799-9BAC-E781C97C2710.jpeg
 
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Art Deco

Well-Known Member
Region
USA
City
Selinsgrove Pennsylvania
I hear this often, but since 2014 I've not had access to any new and wonderful battery tech. So far only promises of a brighter future!
:)
That was the implication of RSN in microcomputers, as well. Really, promises and projections aren't predictions.
 

Sierratim

Well-Known Member
Region
USA
City
Nevada City, CA & Paradise Valley, AZ
That was the implication of RSN in microcomputers, as well. Really, promises and projections aren't predictions.
What's the saying Bill Gates likes to use, "We tend to greatly over estimate technological advances over the next 10 years and tend to greatly underestimate them over the next 100".
 

Art Deco

Well-Known Member
Region
USA
City
Selinsgrove Pennsylvania
I didn't know it was Gates, but I heard it as "a decade" and "a century" of progress. A century ago the 99% (us) didn't have cars or electricity, much less cell phones or ebikes.
 
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Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
DrkAngel thread is what I used for my foray into salvage cells. However, I found new old stock of 18650 battery modules. Stripped them, tested, rewrapped and after reviewing the time spent I never built again. I will build my own from new matched cells this spring if I need a battery.
That's the problem with all these youtube videos and threads that say look at me and how smart I am...
They never give an update 6 - 12 months later that reveal that they would never bother to do that again ;)
 

tomjasz

Well-Known Member
That's the problem with all these youtube videos and threads that say look at me and how smart I am...
They never give an update 6 - 12 months later that reveal that they would never bother to do that again ;)
Not at all true if you follow back through the poster I quoted. Lots of paths, the most difficult are possible with more work than I will invest at my age.;)
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
I'm sure the paths are possible... I'm just not sure that as you wind on down the road if they are worth going down at any age if your intent is a long term solution as the end result is a crap shoot at best rebuilding with used cells.
I do think they are an excellent exercise and knowledge builder and have more of an academic purpose than practical.
 

ebikerxx

New Member
Region
Asia
Let's say I need to charge the battery pack without having to disassemble the kit. Can this be done using the balance charger: SkyRC IMAX B6 V2 60W 6A Charger/Discharger 1-6 Cells.

https://www.skyrc.com/Charger/iMax/b6v2

Case 1: With end caps and strips removed, I connect the 2 pin charger to each cell in the battery pack and charge one cell at a time OR 6 series cells at a time by connecting them using strips?

Case 2: With end caps on, I charge the cell groups using a balance port, however I'm not sure how that would work for a 10s pack. Can I use two balance ports 6s+4s simultaneously?

Does the balance charger: SkyRC IMAX B6 V2 60W 6A, have a BMS, that cuts off the charge as per the high and low cut off voltages configured by us?
 

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Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Let's say I need to charge the battery pack without having to disassemble the kit. Can this be done using the balance charger: SkyRC IMAX B6 V2 60W 6A Charger/Discharger 1-6 Cells.

https://www.skyrc.com/Charger/iMax/b6v2

Case 1: With end caps and strips removed, I connect the 2 pin charger to each cell in the battery pack and charge one cell at a time OR 6 series cells at a time by connecting them using strips?

Case 2: With end caps on, I charge the cell groups using a balance port, however I'm not sure how that would work for a 10s pack. Can I use two balance ports 6s+4s simultaneously?

Does the balance charger: SkyRC IMAX B6 V2 60W 6A, have a BMS, that cuts off the charge as per the high and low cut off voltages configured by us?
Case 1 only as the processor and display can only handle up to 6c at one time.
And yes it acts as a BMS in the sense that you can program the charge by chemistry, voltage and amperage.
I'd suggest that you read the Owners Manual
 

harryS

Well-Known Member
Most people who use batteries w/o BMS are experienced RC hobbyists. They like the lighter weight. They're also want fast, supervised charging so they can get back in the air. The rest of the no-BMS crowd are homeless. Just kidding. The BMS keeps you from running your pack too low and from overcharging it. Both will lead to fires. Ebiking should be set and forget. Even then, I never leave batteries on charge overnight unless I'm looking for a balance charge,

DrkAngel has been less active on Endless Sphere since his building burned down (true ,,, look it up). A few years ago, I overcharged a battery and had a battery too hot to hold. I tossed it in a bucket of water to kill it. $250 in good Panasonic GA xells gone. Try to be careful.
 

ebikerxx

New Member
Region
Asia
The fact that a balance charger can measure internal resistance, along with other features is a real bonus. It has the option of charging various types of rechargeable cells as well which might come in handy. Balance charger will be used sparingly and only while building battery packs. Once I have a working battery pack not sure if I'll be using the balance charger again, might as well rent one if available.

I'm all for un-supervised charging. Mostly, will be charging using my 2 amp charger, and will use a battery pack with BMS for sure, maybe spend a few more bucks to buy a better board. Not a smart one, but a reliable one with temperature sensors and voltage cutoff capabilities.

Speaking of cells, apart from the big 4 companies, the thing I most fear about is wrong labelling, for example, a 18650 cell labelled as a Li-ion and is a LiFePo inside. How does one identify these descrepencies? Maybe by weighing the cells or measuring the internal resistance?
 

ebikerxx

New Member
Region
Asia
Thanks for all your advice. Most manuals are not user-friendly and are loaded with technical jargon. I feel that manufacturers need to adopt a new approach to technical writing by including videos, images and animations to make it more understandable.

IMO Discussion forums like these and online videos are way better to learn stuff instead of reading those boring manuals. At the end of the day, it comes down to your style of learning.

I ordered the SkyRC balance charger with AC/DC input (IMAX B6-AC Charger/Discharger, 1-6 cells), and prepared a 13s2p, 48 volts Battery Pack with 18650 Li-Ion, 3.6 volts, 2200 mah cells of the same manufacturer. Once I get the balance charger, will measure and verify all the cells internal resistance match, before charging the cells.

I'll be using the battery pack with no BMS initially to check the range and make sure all the contacts and connections are fine in the battery pack. If I come across loose connections or contacts issue, I may have to solder the strips and bus bars. Not sure if anyone else using a battery kit have had to weld or solder. Once the contacts issue is sorted out, will add a compatible BMS.

Wish you all at EBR a Happy and Healthy 2021.
 
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tomjasz

Well-Known Member
I ordered the SkyRC balance charger with AC/DC input (IMAX B6-AC Charger/Discharger, 1-6 cells), and prepared a 13s2p, 48 volts Battery Pack with 18650 Li-Ion, 3.6 volts, 2200 mah cells of the same manufacturer. Once I get the balance charger, will measure and verify all the cells internal resistance match, before charging the cells.
F57FD599-0463-45FD-804A-E9A41E8E21B1.jpeg
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Thanks for all your advice. Most manuals are not user-friendly and are loaded with technical jargon. I feel that manufacturers need to adopt a new approach to technical writing by including videos, images and animations to make it more understandable.

IMO Discussion forums like these and online videos are way better to learn stuff instead of reading those boring manuals. At the end of the day, it comes down to your style of learning.

I ordered the SkyRC balance charger with AC/DC input (IMAX B6-AC Charger/Discharger, 1-6 cells), and prepared a 13s2p, 48 volts Battery Pack with 18650 Li-Ion, 3.6 volts, 2200 mah cells of the same manufacturer. Once I get the balance charger, will measure and verify all the cells internal resistance match, before charging the cells.

I'll be using the battery pack with no BMS initially to check the range and make sure all the contacts and connections are fine in the battery pack. If I come across loose connections or contacts issue, I may have to solder the strips and bus bars. Not sure if anyone else using a battery kit have had to weld or solder. Once the contacts issue is sorted out, will add a compatible BMS.

Wish you all at EBR a Happy and Healthy 2021.
I agree with you.... Somewhat 🙃
And I'm definitely more of a hands on learner than reading over technical docs myself... But they do have a useful function.
The problem with only using online forums and videos is that many of the people dishing out advice didn't read the owners manual either 😅
The way I found to use an owners manual best is to start at the beginning, read a paragraph and then do what it explains on the device. Continue on bouncing back and forth until done. You'd be surprised how fast it goes on and how well you understand all in the end. Do that and you'll be the one giving advice and making videos ;)
Read up on the acceptable internal resistance of the brand of cell you have as I'm sure there is a range and since they have some use they will not be exact.