Over the last month the following happened twice in my motorhome setup.
MultiPlus-II 12/3000/120-32, Cerbo GX, firmware 1366/0 which is current. 12V LiFePO4, ~900Ah, SmartShunt for battery monitoring.
Pattern:
After having been off shore power for a couple days (charging via alternator while driving and PV during daytime) and then connecting the vehicle to shore power, the charging starts fine for a couple minutes, then the AC draw just drops to basically nothing (10-15W) and stays there while the unit keeps showing “Bulk” the whole time like it’s charging even though it’s not. DC current stays near zero. I let this run for about 47 hours last time trying to figure out if it would resolve on its own. During that time the state of charge went from ~99% down to 44%.
No error on VE.Bus, no alarms anywhere (ripple, high voltage, overload, all fine), AC input voltage rock steady 227-244V the whole time. So nothing tripped, it just stopped doing anything while still claiming to be in bulk.
Only fix I’ve found is a full power cycle:
Disconnect the MultiPlus from DC completely, wait for several seconds, reconnect, and it comes right back charging the batteries within seconds with the maximum limit set in the Cerbo GX.
Anyone seen this before? Wondering if it’s a known firmware thing with the charge state machine after reconnecting AC post alternator-only period. Happy to post the raw VRM CSV if that’s useful.