Hey guys, I'm making my first A123 packs, just need some advice.
I'm making 3 packs, 6S3P each. 54 cells total, 18 cells per pack. I spent 5 days and cycled each cell, with my Bantam charger, 5amp discharge and 5 amps charge and wrote the mAh down on each cell. The smallest cell from the bunch I will be using is 2092 mAh and the largest is 2219 mAh. Most of the cells are 2140 to 2160. Now, I was told the cells will produce more mAh if charged and dischared at a higher rate. I think I was getting 50 more mAH on each cell when i was charging them at 8 amps, before I decided to charge them all the same at 5amps. Also it's been 60 to 65F degrees where I have been cycling them. I read you guys were checking the voltages after the charge, but It's to late for me to do that. All the cells are 3.35-3.43v after resting for a few days though.
Right now i have the cells layed out:
pack 1: 2092 to 2143
pack 2: 2145 to 2160
pack 3: 2161 to 2219
Is this how I need to make the packs? I wish they were all like pack #2, but I can't afford to be buying more cells. lol. The bad thing is I will be putting these in series to make 59.4V nominal and the first pack will run out before the last pack. I should stay at 2.5v discharge per cell, (45V) to be safe? I won't be using a BMS. I will only have a watt/volt meter display on the handle bar in the circuit.
I was thinking, maybe I should just mix the cells so they are all equal packs? 2092 to 2219 (example)
I just realised that I need to make sure the 3P cells are as equal as possible, no matter what the Series cells are because I will be using a 6S balance tap with the Bantam charger. The charger only can balance the 3 cells as 1.
Thanks
I'm making 3 packs, 6S3P each. 54 cells total, 18 cells per pack. I spent 5 days and cycled each cell, with my Bantam charger, 5amp discharge and 5 amps charge and wrote the mAh down on each cell. The smallest cell from the bunch I will be using is 2092 mAh and the largest is 2219 mAh. Most of the cells are 2140 to 2160. Now, I was told the cells will produce more mAh if charged and dischared at a higher rate. I think I was getting 50 more mAH on each cell when i was charging them at 8 amps, before I decided to charge them all the same at 5amps. Also it's been 60 to 65F degrees where I have been cycling them. I read you guys were checking the voltages after the charge, but It's to late for me to do that. All the cells are 3.35-3.43v after resting for a few days though.
Right now i have the cells layed out:
pack 1: 2092 to 2143
pack 2: 2145 to 2160
pack 3: 2161 to 2219
Is this how I need to make the packs? I wish they were all like pack #2, but I can't afford to be buying more cells. lol. The bad thing is I will be putting these in series to make 59.4V nominal and the first pack will run out before the last pack. I should stay at 2.5v discharge per cell, (45V) to be safe? I won't be using a BMS. I will only have a watt/volt meter display on the handle bar in the circuit.
I was thinking, maybe I should just mix the cells so they are all equal packs? 2092 to 2219 (example)
I just realised that I need to make sure the 3P cells are as equal as possible, no matter what the Series cells are because I will be using a 6S balance tap with the Bantam charger. The charger only can balance the 3 cells as 1.
Thanks