ebike-infected
10 mW
- Joined
- Apr 29, 2012
- Messages
- 32
I have 10 new 5s 4200mah lifepo zippy batteries 16,5v nominal voltage. They're wired to make 8400mah ~80V battery.
Yesterday i was riding 40 km with it, CA said starting voltage was about 83,5V (few hours after full recharge with an icharger) Towards the end of the ride the voltage started to drop, and was at about 77 volts when i came home, it would further drop under 70V when under heavy load on the last straight before base. When i came home i measured the invidual cell voltages with celllog and >80% were showing low and a handful were showing REALLY low. (2,4V or something like that) Handful were still over 3 volts. I immediately parallel-charged them with 1 amp until they were all showing over 3 volts, after that, i charged them with 10 amps until they were 3,2V and after that 20 amps until full. All cells charged okay it seems. CA now reads 83,2V and i recharged the pack about 12h ago.
Can someone explain to me why this happened? By CA readings, i should still have had half of the juice to go by?
How is possible that my pack became so depleted, even when CA said i had only used 4,2 Ah of the (theoretically) available 8,4 Ah?
My strategy was to never use more than 6-7Ah from the battery, and so leave a safe margin and never overdrain the battery but i somehow managed to do it anyway.
Also, can someone explain to me why the invidual cell voltages seem to get unbalanced when the pack is really low or hot off the charger? Once the batteries sit for a while or i drain them a bit by driving, they get very close to same voltage 3,33 - 3,36, most steady at 3,35. Off the charger the voltage may differ as much as ,3Volts. Is this normal? What is acceptable voltage difference? I have balance charged the batteries invidually a few times (recharged the whole set i think 5 or 6 times) The cell voltages and their differencies were pretty much the same whether i parallel-charge or balance charge...
Yesterday i was riding 40 km with it, CA said starting voltage was about 83,5V (few hours after full recharge with an icharger) Towards the end of the ride the voltage started to drop, and was at about 77 volts when i came home, it would further drop under 70V when under heavy load on the last straight before base. When i came home i measured the invidual cell voltages with celllog and >80% were showing low and a handful were showing REALLY low. (2,4V or something like that) Handful were still over 3 volts. I immediately parallel-charged them with 1 amp until they were all showing over 3 volts, after that, i charged them with 10 amps until they were 3,2V and after that 20 amps until full. All cells charged okay it seems. CA now reads 83,2V and i recharged the pack about 12h ago.
Can someone explain to me why this happened? By CA readings, i should still have had half of the juice to go by?
How is possible that my pack became so depleted, even when CA said i had only used 4,2 Ah of the (theoretically) available 8,4 Ah?
My strategy was to never use more than 6-7Ah from the battery, and so leave a safe margin and never overdrain the battery but i somehow managed to do it anyway.
Also, can someone explain to me why the invidual cell voltages seem to get unbalanced when the pack is really low or hot off the charger? Once the batteries sit for a while or i drain them a bit by driving, they get very close to same voltage 3,33 - 3,36, most steady at 3,35. Off the charger the voltage may differ as much as ,3Volts. Is this normal? What is acceptable voltage difference? I have balance charged the batteries invidually a few times (recharged the whole set i think 5 or 6 times) The cell voltages and their differencies were pretty much the same whether i parallel-charge or balance charge...