Battery temperature and unprompted force charge
Posted: Sun Nov 30, 2025 7:30 pm
Slightly odd issue here, on two separate occasions when the cell temp dropped to 3°C the battery started to force charge unprompted.
Heating was enabled both times (on @6C, off at 11°C) but not from grid during this time period.
First time the battery was at 46% SoC so should have been self heating and not allowing the temp to drop that low, the second time SoC was 15%.
First time mode scheduler was on, for the second I had changed to using the force charge period timers - on neither occasion were they calling for a forced charge.
On both occasions the BMS discharge rate was showing 10A (correct for battery configuration and temp) so the batteries should have continued to discharge.
The first time the system was shutdown/restarted which restored on battery operation but heating still did not operate.
The second time I enabled "heat from grid" which brought the battery up to temperature at which normal (expected) operation resumed.
It seems that on my system the battery will only self-heat at >40%SoC if "heat from grid" is enabled (I had hoped BMS 1.009 would have fixed this)
Something is triggering force charge when cell temp drops to 3°C but not if cell temp is less than 3°C when the system is started.
Unfortunately my installer doesn't have a clue.
Any ideas anyone?
Heating was enabled both times (on @6C, off at 11°C) but not from grid during this time period.
First time the battery was at 46% SoC so should have been self heating and not allowing the temp to drop that low, the second time SoC was 15%.
First time mode scheduler was on, for the second I had changed to using the force charge period timers - on neither occasion were they calling for a forced charge.
On both occasions the BMS discharge rate was showing 10A (correct for battery configuration and temp) so the batteries should have continued to discharge.
The first time the system was shutdown/restarted which restored on battery operation but heating still did not operate.
The second time I enabled "heat from grid" which brought the battery up to temperature at which normal (expected) operation resumed.
It seems that on my system the battery will only self-heat at >40%SoC if "heat from grid" is enabled (I had hoped BMS 1.009 would have fixed this)
Something is triggering force charge when cell temp drops to 3°C but not if cell temp is less than 3°C when the system is started.
Unfortunately my installer doesn't have a clue.
Any ideas anyone?