Battery rebound

[RickBradford]

I guess it is common knowledge that a battery's voltage can actually increase just by leaving it lying around not charging, as the reduction in current load can allow the battery to recover.

But I'm wondering about the extent of that. I have a 36V 2P10S Li-ion battery, which gave out while I was riding yesterday, and was showing a voltage of 30.6V. After leaving it for one hour, the voltage had already recovered to 32.9V, and kept going up, albeit at a slower rate, finally topping out at 35.1V.

That seems like a lot of extra volts, and I'm wondering whether something may be amiss with the battery management system which is causing the voltage to drop too quickly when riding, and so enabling this 4V turn-around when it's lying around.

Any advice would be much appreciated.

 

[rich c]

It won't act like a higher voltage for very long when you ride the next time. It'll drop FAST!

 

[fooferdoggie]

This could be a unbalanced battery pack that’s trying to equalize or a bad cell too

 

[harryS]

Not uncommon for my batteries to recover 2 volts immediately after shutting off. Under load, there's always some voltage sag in the cells. With your 2P battery, you;re probably got 2-3 volts of sag, which disappears as soon as the load disappears. Give it a little more tine, you might get another volt. Four is a lot, but probably normal.
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Heck, in my experiments with individual cells, which I discharge to zero so they can be recycled, I;ve seen cells at 0V come back to 2V. There's no power in that 2 volts though, Won't be much power in your 35 volts.
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Word of advice. In my opinion, you will wear a battery out faster running to the point where it shuts off. Unfortunately, a 10S2P isn't very big, so you pretty much have to run it past 50% to go anywhere. I had a few 10S-2P's, but I rarely ran then under 50% and they lasted years,

 

[tomjasz]

Cheap BMS.