Mine started beeping to tell me the battery pack had failed the self-test after 2-years. It held 2x 7Ah 12V LA batteries, I swapped both for the cheapest replacements I could find and it has been running fine for the last 5-years.Oldgreybeard wrote: ↑Sun Dec 04, 2022 5:13 pmI'm having the same problem with my APC UPS, the battery barely lasts long enough to very quickly shut the machine down before cutting out. I've been looking (in vain) for a lithium replacement. The existing battery is a small (7Ah) sealed lead acid one, and it seems to be that if I could swap it for a 4S LiFePO4 pack the thing would have a much greater usable capacity and most probably a long life, too. Only slight snag is how to change the charge voltage. It needs to be reduced to a round 12.4 to 12.6V maximum. Might need to get cunning at making a 4S LiFePO4 pack, with integral BMS, look like a 12V SLA.
I looked into LiFePO4 replacements at the time and you could get them in the correct form-factor, but I flinched at the price. I also considered externally mounting a pair of 110Ah LA batteries, but the existing setup powers my router, network switch and CCTV cameras for c. 2.5hrs so there seemed to be little need.