I have 4 12v AGMs wired in parallel/series for 24v bank with their midpoint monitored from my BMV-712. In the past month or so, once or twice a week I get a midpoint voltage alarm when I discharge below 74%.
The batteries are less than a year old and I think I've taken care of them pretty well, never getting them below 60%. It's very weird that the midpoint voltage doesn't deviate /every/ time my bank is discharged, only some times. For example, in that graph the midpoint voltage was totally fine on the deepest discharge on february 12. In addition, I am sampling from one of the two series midpoints, and it is not linked to the other one because I read here that it could be bad if one of the batteries totally fails. Should I try connecting the two midpoints? Or is there anything else that might be causing his behavior? The batteries never get below 45-degrees.