Lt.Dan
Solar Wizard
Hey y'all, has anybody had their packs long enough, or cycled enough times to actually see degradation yet?
I am currently pulling my 2P16S battery apart to make 2x separate 16S Packs inside of Seplos Mason kits, and while I'm waiting on them to show up, I am capacity testing all of the cells, for better grouping. I'm also purchasing more 280ah cells for a 3rd pack. Bringing my total to 1022ah (theoretical and without degradation).
When I did my initial capacity test when I first got the cells, I had them ranging from 262-285ah, not super happy to get some cells under 271ah, but I got them at a decent price, and I didn't want to deal with refunds/replacements etc. When I paired the highest and lowest cells, I averaged out about 274ah each, or 548ah for the pair. Now over the last year is where I really started to pay attention to capacity. And for the last 6 months, I have been cycling from 3.55v to 2.6v once a month or so, to get an update on capacity and overall pack health. Surprisingly I have noticed the pack in the 499ah-500ah range recently. So while pulling them apart I am going to see if they are all degrading evenly, or if I have some outliers that are really bringing the bank down as a whole.
So far I'm on my 3rd cell, and my first one was 250ah, and 2nd was 257ah. Not looking great.
So I set out to see what is expected with the amount of cycles I have put them through. I've also estimated I'm at about 600 cycles, as I have put them through a full cycle every day, for about 2 years. I also have had a couple encounters with a failing Daly BMS about a year ago, that let the cells go below 2v, so this could also be a reason for lost capacity as well. When looking at cycle life charts, I should be somewhere in the 3-5% degradation mark based on my cycle count and DOD, which 5% of 271ah is 257ah! That puts my mind at more ease.
Has anybody else done some math and found similar results? What did you find?
I am currently pulling my 2P16S battery apart to make 2x separate 16S Packs inside of Seplos Mason kits, and while I'm waiting on them to show up, I am capacity testing all of the cells, for better grouping. I'm also purchasing more 280ah cells for a 3rd pack. Bringing my total to 1022ah (theoretical and without degradation).
When I did my initial capacity test when I first got the cells, I had them ranging from 262-285ah, not super happy to get some cells under 271ah, but I got them at a decent price, and I didn't want to deal with refunds/replacements etc. When I paired the highest and lowest cells, I averaged out about 274ah each, or 548ah for the pair. Now over the last year is where I really started to pay attention to capacity. And for the last 6 months, I have been cycling from 3.55v to 2.6v once a month or so, to get an update on capacity and overall pack health. Surprisingly I have noticed the pack in the 499ah-500ah range recently. So while pulling them apart I am going to see if they are all degrading evenly, or if I have some outliers that are really bringing the bank down as a whole.
So far I'm on my 3rd cell, and my first one was 250ah, and 2nd was 257ah. Not looking great.
So I set out to see what is expected with the amount of cycles I have put them through. I've also estimated I'm at about 600 cycles, as I have put them through a full cycle every day, for about 2 years. I also have had a couple encounters with a failing Daly BMS about a year ago, that let the cells go below 2v, so this could also be a reason for lost capacity as well. When looking at cycle life charts, I should be somewhere in the 3-5% degradation mark based on my cycle count and DOD, which 5% of 271ah is 257ah! That puts my mind at more ease.
Has anybody else done some math and found similar results? What did you find?