I did all my final top balancing and pack testing back in April and then broke down the batteries while I was finalizing my battery boxes and working on other things.
I reassembled them this week and charged each pack back up in series (but did not top balance). One of my batteries had a runner that caused high voltage disconnect and I had a cell in another pack sitting quite a bit lower than the others at full charge. I had not seen any of that behavior from those cells in past testing. I'm at least going to pull the packs apart and clean connections, but wondering if a top balancing is needed again if some cells are self-discharging at different rates. They were just sitting loose for the last ~7 weeks at around 3.3v, not connected in any way. I was charging them around 80a for 272ah cells in 12v packs, which is a bit higher than I was previously testing at, but still a pretty low C rate for that size cell. Should a top balance be needed after only sitting a couple months or is this more likely another issue?
I reassembled them this week and charged each pack back up in series (but did not top balance). One of my batteries had a runner that caused high voltage disconnect and I had a cell in another pack sitting quite a bit lower than the others at full charge. I had not seen any of that behavior from those cells in past testing. I'm at least going to pull the packs apart and clean connections, but wondering if a top balancing is needed again if some cells are self-discharging at different rates. They were just sitting loose for the last ~7 weeks at around 3.3v, not connected in any way. I was charging them around 80a for 272ah cells in 12v packs, which is a bit higher than I was previously testing at, but still a pretty low C rate for that size cell. Should a top balance be needed after only sitting a couple months or is this more likely another issue?