Temperature was the issue I had. After observing charging routines with battery monitors and then with the updated service mode, I noted the V4+ worked flawlessly for about 10 weeks until the temperatures dropped below 40F. Near 30 I got the replace battery message. Pulled the battery and tried charging at 1 amp at below 40F and would not take charge. Increasing to 6 amps charged to 100%.
The latest charging routine I observed would do a high draw (25-30 amps) on startup, then charge at 25 amps briefly then dial down until fully charged to about 14.7 volts. Then the battery would have shallow draw down until about 13.4 volts and zero draw. Float voltage would be +/- 01-.04 amps. If cold, the battery would not take the charge and there was the failure message.
Put the battery back in at warmer temps and worked normally. Ohmmu has a software update due out next month to address this that will be updatable from the app. Future models will have silicone heating mats between cells but they have indicated they are not really necessary. I suppose you would want that if living in -25F and below climates like upper midwest and Canada. But at those temperatures even a lead acid would be problematic.