Is my scooter battery dead?

Hello i need advice on my scooter battery.

Its a 60v 28ah pack from 2011.

If i charge it i can drive 10km.
It used to be 50km.
I opened it up and 2 off the 17 clusters where below 4.02v.
1x 3.62v and 1x 3.49v
the rest was 4.02v

should i desolder them all and test every single cellike 18650's?
Any thoughts on where i can find these cels to recycle?
they look like cels used in apple laptops.
Or just make a new one from recycled 18650?

Btw i love this form learned allot just by readingthis week thanks all

Sounds to me like your bms may have failed in the balancing department. Take out the bms, disconnect all serial connections and charge each bank of parallel cells to full voltage. Then let it sit for about a week and then recheck the voltages.
Also, do a heavy load test on each parallel bank and see if any of them drop more voltage under load than any other set. If it does, then you have a bad cell in that group of parallel.
I would do a load test before and after the resting period. I would also wait 2-3 weeks instead of 1 if possible.

First of all manually balance them all up to 4.1V or something. The lowest one you had will affect the whole pack. And it might be that the balance board cant keep up anymore due to that one way low. If that doesnt help then testing each one is a good start but you can also

Balance them all up to max and then slowly run whole pack down untill you see 1 or more packs driting away with lower voltage faster. That will show a weaker cell

Korishan said:

Sounds to me like your bms may have failed in the balancing department. Take out the bms, disconnect all serial connections and charge each bank of parallel cells to full voltage. Then let it sit for about a week and then recheck the voltages.
Also, do a heavy load test on each parallel bank and see if any of them drop more voltage under load than any other set. If it does, then you have a bad cell in that group of parallel.
I would do a load test before and after the resting period. I would also wait 2-3 weeks instead of 1 if possible.

Click to expand...

Thanks for this!
Need a bigger soldering iron tho

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daromer said:

First of all manually balance them all up to 4.1V or something. The lowest one you had will affect the whole pack. And it might be that the balance board cant keep up anymore due to that one way low. If that doesnt help then testing each one is a good start but you can also

Balance them all up to max and then slowly run whole pack down untill you see 1 or more packs driting away with lower voltage faster. That will show a weaker cell

Click to expand...

Thanks can i just do it like this? Also made a pic off my balance-board.



baking eggs on the imax now....

You can balance them all together by disconnecting from series and connecting them all in parallel. This will get them all balanced with each other. You could probably do your load tests this way to start. Then if there are issues with voltage drop, split the combined back in half and test again and keep doing that to the weak side until you find your pack.

update its easy to find the bad cels because they swell more or les.....

Swelling as a result of gas generation during charge and discharge is a concern. Battery manufacturers insist that Li-ion batteries do not generate excess gases that can lead to swelling when properly used. Nevertheless, some swelling can occur and most is due to faulty manufacturing. The pressure from swelling can crack a battery cover open and in some cases break the display or electronic circuit. Manufacturers say that an inflated cell is safe. While this may be true, do not puncture a swollen cell in close proximity of fire or heat; the escaping gases can ignite.

when i try to charge cels that are under voltage they swell even more so i wil get ride of those.
i ordered 15 new ones and will replace them.