I've just finished putting together a fairly modest 12V system in my Transit camper — 200Ah of lithium (a Fogstar Drift 200Ah), a Victron SmartSolar MPPT 100/30 pulling off two 175W panels, and a Giandel 2000W pure sine inverter I picked up secondhand. Everything seemed fine on the bench but now it's all wired up I'm getting some odd behaviour.
The issue is that when the inverter kicks in under any decent load (kettle, drill, that sort of thing), the SmartSolar seems to panic and drop out of bulk charge, sometimes resetting back to float even though the battery is sitting at around 50% SOC. The BMS on the Fogstar isn't throwing any errors and the voltage at the battery terminals looks stable on my multimeter — sitting around 13.1V under load. I've got the SmartSolar configured for lithium with absorption at 14.2V and float at 13.5V.
Has anyone seen something similar? I'm wondering whether it's a grounding issue, interference from the inverter, or whether the MPPT just doesn't like sharing a bank with a cheap inverter pulling big current spikes. Happy to dig into cable runs and fusing if that helps narrow it down.
