Anyone else had grief with their Victron Multiplus cutting out under heavy load?

Been running a Multiplus 12/3000/120 in my off-grid shed setup for about eight months now and it's been mostly brilliant, but I've started getting random shutdowns when I pull big loads. We're talking my angle grinder (about 1800W) and the workshop lights on at the same time — so maybe 2200W sustained. The unit throws up a low battery warning on the VRM portal even though my batteries are sitting at 12.6V before the load hits.

I've got four 200Ah Battle Born LiFePO4s wired in parallel, so 800Ah total at 12V. In theory that should be more than enough to handle this kind of draw without the BMS kicking in, but I'm wondering if it's a cabling issue. My battery-to-inverter cables are 70mm² and about 1.2 metres each side — seemed adequate when I put it together but maybe there's too much voltage drop under that surge?

Has anyone dialled in the low voltage cutoff settings through VEConfigure to give themselves a bit more headroom, or am I barking up the wrong tree entirely? Happy to share my VEConfigure screenshots if that helps. Wondering if others have had similar with parallel battery setups specifically.

@Rodney3 classic Victron telling you it's technically your fault in the most polite way possible — check your DC cable sizing, because 3000W at 12V is pulling 250A and most people's wiring is basically an angry extension lead at that point.

@Rodney3 eight months of bliss then betrayal — sounds like my ex, and also like a temperature shutdown; have you checked whether it's tripping the high-temp alarm or an overload code in VictronConnect, because those are very different problems wearing the same "random cutout" costume.

@Rodney3 worth checking your battery BMS isn't quietly pulling the plug on proceedings — mine on the narrowboat did exactly this under kettle-plus-microwave combos until I realised the Fogstar cells were hitting their discharge current limit and cutting Victron off at the knees before it could even complain properly.

Check your VictronConnect app → live data → see if DC voltage is nosediving just before shutdown; if it's cratering below ~11V that's your BMS doing a dramatic exit, not the Multiplus itself throwing a wobble.

Upgrade your BMS current threshold or rethink the load sequencing and you'll be golden. 🔌