I bought a 72v 20amph battery, 30 amp continuous 50amp max BMS. When I got it the voltage was 68v. I cycled it a few times and the maximum voltage it reaches before the charger shuts of is 83v. After about a day it drops to about 82.5v. Is this normal? Should it charge to 84v? I'm wondering if it may have bad cells based on these voltage numbers. The charger voltage is 84.5v.
Thanks
I bought a 72v 20amph battery, 30 amp continuous 50amp max BMS. When I got it the voltage was 68v. I cycled it a few times and the maximum voltage it reaches before the charger shuts of is 83v. After about a day it drops to about 82.5v. Is this normal? Should it charge to 84v? I'm wondering if it may have bad cells based on these voltage numbers. The charger voltage is 84.5v.
Thanks
Because you didn't post the battery chemistry I am assuming that your pack is a Li-ion battery pack. Something like 20s?
(72v / 3.6v = 20 cells) and (20 x 4.2v = 84v)
If your cells are not charging all the way to 4.2v then it could be a few things. Your Multi meter is a bit off. Your BMS is bleeding them down to 4.15v per cell. One or more of your cells don't charge to 4.2v causing a lower then expected terminal voltage.
As for you pack to bleeding down to 82.5v that is normal for a pack with the kind of bms that slowly drains a battery pack.
If your pack delivers 1400wh during usage, I wouldn't worry about it too much. If you pack delivers substantially less then the expected 1400+ watt hours, become concerned.
I bought a 72v 20amph battery, 30 amp continuous 50amp max BMS. When I got it the voltage was 68v. I cycled it a few times and the maximum voltage it reaches before the charger shuts of is 83v.
Yes it's a 20s lithium ion from China so I don't know much about the cells. When the weather permits I will get some accurate measurements on total watt output. I was concerned that if it did reach 84v then it meant for sure bad cells but that's not necessarily the case.
Thanks
