Don't know all the ins and outs of it, but note that battery resistance is higher when nearly full that at say 50% SOC, so the critical situation the OP reports and my test shows is with the higher sort of batt resistance, as occurs when controller reaches high set point.
I got a 0.2v jump more or less with my four 6s as a bank, where batts are in good shape. So a brief jump to 15 from 14.8 seems possible. But not sure why inverter does not revert to normal when voltage drops below 15 instead of needing a reset. (IIRC the OP)
His 14.4 (if real and not like my 14.4 vs 14.6 nominal) is way too low below 15 to take care of this, so something else must still be going on there I guess.
I see my unloaded voltage is about 14.6, which is the high set point, so that means the loaded voltage is lower (natch!) as seen, so how come the OP's unloaded voltage goes over his set point---weird!!!???
Anyway, that's what I got for what its worth. Can't think of another way to test it out.
