Hi, I am not sure if this is the right forum, but this USP Cyberpower 650VA when plugged in works for 7-10 min, and dies, I cannot restart it. Surge protector side works perfectly when plugged. When disconnected, it works for 30 min or so, so the battery must be ok, right? not sure what is wrong with it.

Any idea? Thanks a lot. I don't want to throw it in the garbage.

One of the cells within my rackmount cyberpower UPS seems to be failing, it is constantly at 13V+ while others are at <12. It uses an odd 12v 6Ah batteries (Leoch DJW12-6.0FR). Most of the batteries within the same form factor are 5AH and the closest match I was able to find (Leoch LP12-6.0WT1) have both positive and negative terminals on the same side (whereas original battery has the positive on the "front / label" side and the negative on the rear), I'm primarily worried that the original wiring harness would prove too short for terminals on the same side.
Battery pack itself is RB1260x8 aka RBP0130