This weekend, I proceeded to charge the battery banks. They were bottom balanced at 3.2v.
One thing that surprised me was that when each bank reached individual cut-offs of 3.65v (it cut off when the first cell passed 3.65v), the ChargeMOS indicated cutoff. However, both continued to charge the eight cells. Also, the cells reached different levels of charge and both packs had different cell charge readings (ie. #1 cell on one pack had higher charge and didn't on other pack).
I observed this on BOTH Ant BMS that I am using. That leads me to believe there may not be cell-level cut-off. I may attempt to charge up to the 28.8 limit to see if it cuts off when that occurrs.
Also, even though the bms alarm sounds and chargeMOS shows 'off' and the cells show a high voltage (up to 4v), when I disconnect the charger, they all settle down to about 3.4v or about 80% charge.
These were reputed to be Class A fresh cells but are retaining charge closer to what a used cell would support. Do I need to top balance to a greater limit (4v?)?
The cells are CALB 3.2v nominal, 3.65v max, 100ah cells from Basen Technologies in China. Highly reputable.
NOTE: When I charged across packs of 4 cells (12v config), I was able to get a more uniform charge than when I attempted to charge across 8 cells for a 24v pack. The charger is 'smart' and detects 12 or 24v. The chargers are smart 12/24v, Li-ion, lead, Lifepo4 switchable. 10amp at 12v and 5amp at 24v. I may connect the Aims whole system charger to see if the balancing behavior differs.
Also, I found that close attention is required when assembling ring connectors to the balancing leads. I have discarded one harness as it had very poor performance across all 8 cell connections. I had spare BMS and assembled a backup harness. But, I may have some modifications to make as 1-2 cells on each pack are reading lower than the rest. But, it may be bad cells or bms. Many variables.
One thing that surprised me was that when each bank reached individual cut-offs of 3.65v (it cut off when the first cell passed 3.65v), the ChargeMOS indicated cutoff. However, both continued to charge the eight cells. Also, the cells reached different levels of charge and both packs had different cell charge readings (ie. #1 cell on one pack had higher charge and didn't on other pack).
I observed this on BOTH Ant BMS that I am using. That leads me to believe there may not be cell-level cut-off. I may attempt to charge up to the 28.8 limit to see if it cuts off when that occurrs.
Also, even though the bms alarm sounds and chargeMOS shows 'off' and the cells show a high voltage (up to 4v), when I disconnect the charger, they all settle down to about 3.4v or about 80% charge.
These were reputed to be Class A fresh cells but are retaining charge closer to what a used cell would support. Do I need to top balance to a greater limit (4v?)?
The cells are CALB 3.2v nominal, 3.65v max, 100ah cells from Basen Technologies in China. Highly reputable.
NOTE: When I charged across packs of 4 cells (12v config), I was able to get a more uniform charge than when I attempted to charge across 8 cells for a 24v pack. The charger is 'smart' and detects 12 or 24v. The chargers are smart 12/24v, Li-ion, lead, Lifepo4 switchable. 10amp at 12v and 5amp at 24v. I may connect the Aims whole system charger to see if the balancing behavior differs.
Also, I found that close attention is required when assembling ring connectors to the balancing leads. I have discarded one harness as it had very poor performance across all 8 cell connections. I had spare BMS and assembled a backup harness. But, I may have some modifications to make as 1-2 cells on each pack are reading lower than the rest. But, it may be bad cells or bms. Many variables.
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