Alfalfameister
New Member
- Joined
- Feb 21, 2020
- Messages
- 50
A friend didn't top balance his cells. I would have lent him my benchtop power supply, but he didn't know I had one, and now too much hassle for him to disassemble pack (rather tight location and all that).
He did connect them in parallel for two days (but reading in this forum, that didn't really do a lot of good).
Anyway, he has a Smart Daly BMS, and he set HVD to 3.60v and LVD to 3.0 (or 2.9, I think).
His charger is set to 55v only. It's all fine and dandy and charges fine, but once one cell hits 3.5, it shoots up to 3.6v within a few minutes (the rest are still in the 3.37 to 3.39v range).
BMS cuts off charging, and the 3.6v goes down to 3.5v within a few minutes, then charging starts over (3.500v voltage "release" - BMS turns off charging when one cell hits 3.600v, and resumes charging only when that cells gets back to 3.500v)
This happens (well, when he gets to fully charge) several times (about 4-5 times), then finally the 3.6v takes an hour to go back down to 3.500v (then it may resume charging, but within minutes hits 3.6v, and again takes a long time to drop to 3.500v).
I know the BMS tries to balance the cells, but it cannot keep up the "burning off the extra charge" with the charge rate (and the balancing function turns off anyway when the BMS disconnects the charger - only balances while charging).
Questions:
1. Is this bad for the BMS (hitting the HVD of one cell and disconnecting the charger), esp when it does this several times per day?
2. Will his cells eventually get balanced? (even if it takes months?)
He is happy with the performance of the battery pack (EVE 280Ah 16S config), and doesn't need to eke out ALL the performance, but he is worried if it's bad for the BMS to be hitting the HVD and disconnecting the charger.
One other thing: he once tried changing the charging voltage to 54v, and that one cell never hit 3.6v (it hit 3.5v, and the others slowly were catching up - I guess the balancer, when the charger was only charging at less than 1A, could keep up). But he said 54v charge rate not going to work for him, as when he hits about 60% SOC, charging slows down too much.
He did connect them in parallel for two days (but reading in this forum, that didn't really do a lot of good).
Anyway, he has a Smart Daly BMS, and he set HVD to 3.60v and LVD to 3.0 (or 2.9, I think).
His charger is set to 55v only. It's all fine and dandy and charges fine, but once one cell hits 3.5, it shoots up to 3.6v within a few minutes (the rest are still in the 3.37 to 3.39v range).
BMS cuts off charging, and the 3.6v goes down to 3.5v within a few minutes, then charging starts over (3.500v voltage "release" - BMS turns off charging when one cell hits 3.600v, and resumes charging only when that cells gets back to 3.500v)
This happens (well, when he gets to fully charge) several times (about 4-5 times), then finally the 3.6v takes an hour to go back down to 3.500v (then it may resume charging, but within minutes hits 3.6v, and again takes a long time to drop to 3.500v).
I know the BMS tries to balance the cells, but it cannot keep up the "burning off the extra charge" with the charge rate (and the balancing function turns off anyway when the BMS disconnects the charger - only balances while charging).
Questions:
1. Is this bad for the BMS (hitting the HVD of one cell and disconnecting the charger), esp when it does this several times per day?
2. Will his cells eventually get balanced? (even if it takes months?)
He is happy with the performance of the battery pack (EVE 280Ah 16S config), and doesn't need to eke out ALL the performance, but he is worried if it's bad for the BMS to be hitting the HVD and disconnecting the charger.
One other thing: he once tried changing the charging voltage to 54v, and that one cell never hit 3.6v (it hit 3.5v, and the others slowly were catching up - I guess the balancer, when the charger was only charging at less than 1A, could keep up). But he said 54v charge rate not going to work for him, as when he hits about 60% SOC, charging slows down too much.