EG4 › MPPT / charge controller
Battery won't charge despite normal PV readings
reported more than once
Symptoms
- Battery charges poorly or not at all from available solar or grid power even though PV and AC input read normally
- Culprits found across cases include 'Charge Last' selling PV to the grid before charging, Battery Priority Start time routing all PV to the battery before loads and stalling inversion for hours, Weather Optimizer silently re-enabling AC Charge after Quick Charge, a charge-source-priority setting (option 16) left on SNU instead of CSO, Off-Grid mode not honored after a firmware update, and scheduled force-discharge refusing to start once the battery is at 100%
- And on a paralleled FlexBOSS21 pair, one or both inverters repeatedly dropped output from 6-7kW to about 2kW for a few minutes at a time, several times a day, at a consistent solar-output level, until the working mode was changed to 'Charge battery last'
The cause and the fix
Subscribers see the cause, the fixes that worked and who did them, part numbers and recent prices when a part is involved, and the field reports behind this entry.