Maast
Compulsive Tinkerer
I've been doing battery life cycle testing on a nominal 277AH battery. It's taking forever and I'm only getting two cycles a day.
The testing is charging up to 3.65v at roughly 80A (varies a lot over the charge cycle) and then a discharge at ~85A to 2.8v. Call it a 98% DOD. If I run it down to 2.5 I only get another 5-8 AHs as found on another battery of the same model and AH capacity. This is on a virgin batt. I will do the same test on a identical battery using a 80% DOD after this.
Results:
The first 8 cycles I got a steady 286 AHs, on cycle 9 it went down to 285 AH.
So, that 1AH loss for every 9 cycles. 80% of 286AH is 229AH of actual capacity. 80% of rated capacity is 222AH.
Using the rated capacity, 286AH minus 222AH = 64AH I can lose giving me only 576 cycles before I'm down to 80% of nominal capacity. Bummer.
Caveat: I dont know exactly how linear the degradation is, it may smooth out after an initial drop. I will continue testing until I get enough data points to make a firm conclusion, probably 200-300 cycles and edit this post as the test continues.
The testing is charging up to 3.65v at roughly 80A (varies a lot over the charge cycle) and then a discharge at ~85A to 2.8v. Call it a 98% DOD. If I run it down to 2.5 I only get another 5-8 AHs as found on another battery of the same model and AH capacity. This is on a virgin batt. I will do the same test on a identical battery using a 80% DOD after this.
Results:
The first 8 cycles I got a steady 286 AHs, on cycle 9 it went down to 285 AH.
So, that 1AH loss for every 9 cycles. 80% of 286AH is 229AH of actual capacity. 80% of rated capacity is 222AH.
Using the rated capacity, 286AH minus 222AH = 64AH I can lose giving me only 576 cycles before I'm down to 80% of nominal capacity. Bummer.
Caveat: I dont know exactly how linear the degradation is, it may smooth out after an initial drop. I will continue testing until I get enough data points to make a firm conclusion, probably 200-300 cycles and edit this post as the test continues.
