My BMS keeps shutting off — troubleshooting help

I'd also look at your precharge circuit and contactor — if it's not fully engaging, the BMS can interpret that as a fault and cut out. Same thing happened with my motorhome setup last year and I spent weeks chasing phantom voltage drops before realising the main contactor was sticky.

What's your load like when it shuts down? If it's cutting during high discharge, could be a current limit issue. Check what your BMS has configured for max continuous discharge — some Victron units ship with conservative defaults that don't match your actual setup.

One thing @GrumpySparky and the others haven't mentioned: temperature sensors. If your BMS has temp monitoring enabled and there's a dodgy sensor, it'll shut you down even when things are actually fine. I've seen more of those false trips than actual thermal issues.

What does the Victron app show when it cuts? Any error codes in the logs? That'll narrow it down massively. If you're not already monitoring it, get the smart dongle sorted first — makes troubleshooting infinitely easier.

Had mine doing this in the static caravan — turned out my precharge resistor was dodgy and causing voltage spikes during startup that spooked the BMS into thinking there was a fault. Swapped it for a proper 1kΩ unit and haven't looked back.

@ExChippie's spot on about the contactor, but also worth checking if you've got any loose terminals on the shunt — mine was corroded underneath and giving duff readings, so the BMS thought the battery was doing something weird when it wasn't. Cleaned it up with some contact cleaner and bingo.

One other thing: what's your cell voltage spread like? If one cell's even a tenth of a volt dodgier than the others, a sensitive Victron will chuck a wobbler about it. Might be worth balancing manually if you've got an imbalance creeping in.

Has anyone checked whether it's a firmware issue? I had something similar on my van setup last year — the Victron firmware had a known bug that caused nuisance shutdowns under specific load conditions. Worth checking what version you're running and if there's an update available through the app.

Also, quick question for @RussScott — are the shutdowns happening at particular times or under specific loads? Mine would only trigger when the inverter was delivering above a certain threshold combined with low ambient temperature. Took ages to spot the pattern.

One other thing: what's your actual cell voltage spread like? If you've got cells drifting more than 50-100mV apart, the BMS gets twitchy. I'd grab a decent multimeter and check all of them individually like @BayLisa suggests — my shepherd's hut battery has four cells that were consistently out of balance, and it was causing all sorts of grief until I sorted it with a Fogstar balancer.

What voltage are your cells sitting at when it cuts out? That'll narrow it down quite a bit.

Bet you've got a dodgy cell in that pack creating intermittent voltage wobbles — LiFePO4 cells are usually rock-solid until they're not, then they're really not.

Before you start replacing things, stick a multimeter across each cell group while it's doing its thing (or just after if you can catch it). If one's sitting noticeably lower than the others, that's your culprit. Shepherd's huts get proper temperature swings — cold weather can mask a failing cell until it decides to throw a wobbler.

@ExChippie's spot on about the precharge circuit though — worth checking your contactor's actually clicking in fully. If it's halfway engaged, the BMS sees that as "something's definitely wrong" and cuts out to protect itself.

What's your actual error code when it shuts down? The SmartBMS is usually quite chatty about why it's having a strop — that'll narrow it down quicker than replacing everything in sight.

Worth checking your cell balancing state — if one cell's drifting, the BMS will cut out to protect itself. Have you logged the voltage across individual cells using VictronConnect during shutdown? Also verify your shunt calibration; I've seen dodgy shunts report phantom overcurrent conditions that trigger the cutoff. What's your current limit set to?

@RussScott, worth checking your cable connections and battery terminals first — loose connections can cause voltage fluctuations that trigger protective shutdowns. Also, what's your ambient temperature doing? LiFePO4 can get finicky in cold conditions. If everything's tight and warm, logging your cell voltages during a cutout event would help identify whether it's a balancing or hardware issue.

Had similar grief with mine last year. Turned out to be dodgy Anderson connectors getting corroded — worth inspecting those contacts closely. Also check your BMS shunt connections, they're surprisingly easy to loosen over time especially in a moving setup like a boat. What voltage is it cutting at?

Have you checked your BMS settings in the app? I'd look at the cell voltage thresholds first—if they're set too tight, even minor imbalances trigger shutdown. Also worth logging actual cell voltages under load for a few charge cycles. The SmartBMS is fairly bulletproof, but I've seen firmware updates solve phantom cutouts before. What's your charge current set to?