13s10p battery pack repair(noob experiment). Help appreciated!

Joined
Aug 13, 2021
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16
Hello!


Very thankful for advice!

I am trying to make one functioning battery from my two broken scooters while trying to learn some DIY battery making in the process.

The battery specs are: 48v 25ah 13s10p

The first scooter arrived broken and the seller (AliExpress) quickly took it away from production.

https://m.aliexpress.com/item/4000102603320.html?spm=a2g0n.order_detail.0.0.4ff7f19crviuHv

This battery measured 13,1v through the BMS and 19,5v when removed. 7 of the parallel groups were at 0v.

The second scooter ran for a few months (roughly 20-30 cycles) until it also broke down. It was never charged above 80% or ran below 20% charge.

I am suspecting the tiny mysterious BMS could possibly be lacking a balancing feature which perhaps could explain the short/lack of lifespan.

I am waiting for my opus bt-c3100 to arrive so that I also can test the capacity of the individual cells.


Could I be right in my suspicions? Any other thoughts?
 

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fjodorlogin said:
I am waiting for my opus bt-c3100 to arrive so that I also can test the capacity of the individual cells.
Are you saying both batteries have p-groups that are still usable to the point of at least 13 or more 'good' parallel groups. Can you remove the poor parallel groups in the battery that still has the most 'good' p-groups. Then replace them with p-groups that are still good enuf from the other battery with more 'no-good' p-groups?

Assuming each battery with at the most 'good' p-groups are within 100mV of each other no serious damage at this point. Probably just need a new (GOOD) BMS (maybe a "smart" BMS).

IMO, you may be Jumping the Gun by having already ordered an Opus bt-c3100. In the meantime you could possibly balance at least 13 good p-groups yourself (within 100mV of each other) with some ingenuity on your part and hold-off on complete disassemby and using the Opus bt-c3100 for now, and order a DALY (maybe a 'smart') BMS.

Even if the cells in that battery are sub-par you could still prolong their life with proper use and care ... :) ... Most likely problem caused by a cheap BMS.

When you remove and replace both the 'no-good' with the 'good' p-groups do it in such a way so the bus bar strips can be slightly overlapped for soldering between the cells instead of directly over/on the cells.
 
Yea I am almost positive that I still have enough p-groups, otherwise my plan was to reduce capacity by making smaller p groups. Thank you for your advice!! I cancelled the opus order for now.
 
Two more details that might be worth mentioning,

1. I have not been able to find any spec sheet on these cells so all I "know" is that they are 2500mah, 3,7v.
(This was the reason I ordered the opus)

2. I have a spot welder
 
You need to think thru what is the least invasive way of salvaging the 'good' 10p groups without completely disassembling and starting over with at least 130 'good' cells.

Have you yet measured and recorded the voltages of the twenty-six 10p groups (in both batteries) to determine what 10p groups you still consider 'good' enuf?

How much voltage variance is there between these ('good') 10p groups in each battery? Hopefully the 'good' 10p groups (in each battery) will have variances no greater than say 150mV to 200mV from each other (maybe, maybe not)?

Once you determine at least thirteen of the 10p groups that you consider 'good' enuf you can then proceed with your surgery. Then balance all of the 'good' 10p groups via a combination of charge and/or discharge so they're all within 30mV of each other (e.g. 3.60V) before reassemby of a 'good' 13s10p battery and 'good' BMS. Need a DMM that reads to 3 decimal places ... https://www.amazon.com/gp/product/B07TWQ4ZSJ/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

It's too early to start individual cell disassembly to determine how many not-so-good cells may still still be usable for another DIY 18650 project.
fjodorlogin said:
(This was the reason I ordered the opus)
No hurry ... maybe as a winter project after you've successfully rebuilt a 'good' 13s10p pack with a 'good' BMS (haste makes waste so take your time and do it right the first time) ... :thumb:
 
You've got one battery with 7 rows at zero volts. What's the voltage on the other 6 rows? I would ask the same for the second battery.

I'm conservative about re-using old cells. Anything that went below 2 volts long term is dead to me. Others might feel differently.
 
docw009 said:
You've got one battery with 7 rows at zero volts. What's the voltage on the other 6 rows? I would ask the same for the second battery.

I'm conservative about re-using old cells. Anything that went below 2 volts long term is dead to me. Others might feel differently.
Is it possible that NONE of the voltages in the 13 p-groups in the other battery are no lower than say 3.00V to 3.30V with several even higher? Would you proceed as following or IF NOT what would you suggest besides or other than my following suggestion ...

If that's the case (he previously removed the BMS) just rebalance all 13 p-groups individually via a combination of charge (and/or disharge) to nominal voltage. Then charge the battery to 50.0V (p-groups around 3.85V). Let sit for 5 days and record any voltage variance change among the 13 p-groups. If no significant difference (no variance greater than say 30mV) that 13S10P battery still has cycle life to give (usable IMO). Then you can use the other battery as a rebuild project (e.g. 12S6P), and order that OPUS cell capacity tester.
 
Wow you guys are awesome! :bigthumb:

Thank you for now, I will make a new post shortly when I have tested the inividual parallel groups of the second battery.
 
Again, thank you all for your help :D :thumb:

If you are still interested to follow this project, check out PART 2: https://endless-sphere.com/forums/viewtopic.php?f=14&t=116511
 
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