BMS destroyed my battery?!

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goatman   100 MW

100 MW
Posts: 2888
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: BMS destroyed my battery?!

Post by goatman » Apr 05 2021 10:14am

john61ct wrote:
Apr 05 2021 2:11am
goatman wrote:if they had a bluetooth bms like the Ant bms
you could set the lvc at 2.5v
program balancing to start at 2.8v
I've never heard of a protective BMS that bottom balances.

Only dedicated balancers ( marketed as "non-protective BMS") or node charging can middle or bottom balance afaik

> i think charging to 4.2v killed it

No way, that has a relatively minor impact on longevity.

Using second-hand cells is inherently risky even if only 1P

Given that many will be past EoL, putting them in parallel groups astronomically increases the odds of quick pack failure

even with rigorous testing of each cell individually and discarding the majority.

If you want a reliable pack you have to buy a known good cell model

new, Grade A from a reliable source
on the ant bms you can program it to start balancing at whatever voltage you want
turn it on, turn it off
its an easy way to do bottom balancing and pack maintenance
then turn off the balancing function til next time

time stamped
https://youtu.be/Z7M_kNB7ltI?t=646

if i bottom balance to 3.0v
thats my lvc
all the cell groups should hit 3.0v all at the same time under load
at rest they will bounce back to 3.3v/3.4v
like you say, stay away from the shoulders

john61ct   100 GW

100 GW
Posts: 7539
Joined: Dec 18 2018 2:06pm

Re: BMS destroyed my battery?!

Post by john61ct » Apr 05 2021 11:46am

This looks like a good seller?
https://www.ebay.com/itm/313014455885

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