Quattro-II's inverter trips out; device appears to crash and restart

Had a similar gremlin with my garden office setup — Victron kit playing silly beggars under heavy load is basically a rite of passage at this point.

Mine was a Quattro-II 48/5000 rather than the 24V version, but the crash-and-restart behaviour under inverter load spike felt identical to what you're describing. Turned out my Fogstar Drift cells were sagging harder than expected under surge demand, the BMS was hitting its overcurrent threshold and yanking the rug out from under the Quattro before it could even negotiate gracefully — looked like a crash, was actually just the BMS doing its job too enthusiastically.

Few things worth poking at:

• Check your VRM logs — the Cerbo GX will have timestamped exactly what tripped first, inverter or BMS
• DC cable run length and gauge — voltage drop under surge load on a boat is brutal, especially if runs are longer than you'd think
• BMS overcurrent setting — some Fogstar configs ship quite conservative out of the box
• ESS assistant vs standalone inverter mode — sometimes the assistant stack on the Quattro needs reordering after a firmware update

The 24V topology is inherently pulling double the current of a 48V equivalent for the same wattage, so your cabling and BMS limits are doing twice the work — boats especially love to hide a dodgy crimp somewhere in that equation.

Anyone else seen the Cerbo GX log something useful in these scenarios, or does it tend to miss the actual trigger event? Curious whether the VE.Bus error codes are pointing anywhere helpful for the OP.

@BayFrank worth checking your DC cable sizing before anything else — undersized cables cause voltage sag under load, the BMS sees a low-voltage event and pulls the plug, which looks exactly like a random crash/restart cycle.

On my shepherd's hut Quattro-II setup I was seeing identical behaviour until I measured actual voltage at the battery terminals versus at the inverter DC input under load. Had nearly 0.8V drop across 2m of cable — embarrassing in hindsight. Went up to 70mm² tinned copper and the issue vanished completely.

Also worth checking your BMS communication is properly configured in VictronConnect — if the DVCC settings aren't talking correctly to your battery's BMS, the Quattro can get contradictory signals and essentially panic.

What battery chemistry are you running? That'll narrow it down considerably.

@BayFrank @ExPostie82 makes a fair point on the cable sizing, but once you've ruled that out, have a look at your BMS communication settings — specifically whether your BMS is sending a correct charge/discharge current limit to the Quattro-II via DVCC.

I've seen the inverter trip and restart exactly as you're describing when the BMS throws an unexpected current limit of zero, essentially telling the Victron to shut everything down. Catches a lot of people out.

Check the VRM portal logs if you've got a Cerbo or Venus GX — the event history usually tells you precisely what triggered the shutdown rather than guessing. Makes diagnosis much quicker.

What BMS are you running alongside it?

@ExPostie82 and @ExFirefighter59 have covered the obvious culprits, so I'll add something often overlooked: cell imbalance causing premature BMS cutoff under load.

If your pack has even one weak cell, voltage depression across that cell during high-current draw can trigger an undervoltage protection event at the BMS level — which to the Quattro-II looks identical to a catastrophic DC dropout, hence the crash-restart cycle.

Worth pulling your BMS logs if it supports that (JK BMS and Daly both do via Bluetooth apps). Look specifically at per-cell voltage spread during the trip event rather than pack-level voltage, which can look deceptively healthy.

On my Fogstar Drift 48V setup I had a 40mV spread that only appeared under 3kW+ loads — invisible until I actually graphed the cell data properly.

@CrafterDream raises a solid point on cell imbalance — worth adding that if your BMS is cutting out due to imbalance rather than a genuine over-current event, you'll often see it correlate with State of Charge dropping below ~20%, where voltage divergence between cells becomes most pronounced.

On my cabin setup I log BMS events via a Cerbo GX and cross-reference timestamps against the VRM portal data. That correlation exercise alone told me far more than guesswork ever would. If you're not already doing this, it's worth the effort.

Also worth checking: what discharge rate does your BMS permit versus what the Quattro-II is actually demanding? A 5000VA inverter pulling near its limit into a resistive load will demand serious current — if your BMS is rated conservatively, it'll trip before the Victron even blinks.