Anyone else had grief with their Victron MultiPlus II tripping on high loads — 48v system?

Been scratching my head over this one for a few weeks now. I've got a MultiPlus II 48/3000/35 hooked up to a 48v 200Ah LiFePO4 bank (Gobel cells, 16s), and it keeps cutting out when I run the kettle and microwave at the same time — around 2,800W combined. The inverter just trips and throws an overload warning in VictronConnect, even though we're well within the 3,000VA rating on paper.

I've gone through the usual suspects — checked all my cable runs (35mm² throughout, kept under 1.5m from battery to inverter), terminals are tight, BMS isn't the one tripping (confirmed via the Daly app). Battery voltage under load is sitting around 51.2v, so it's not a low voltage cutoff issue. The odd thing is it only seems to happen when both appliances kick in within a second or two of each other, suggesting it might be an inrush current spike rather than a sustained overload.

Has anyone played around with the assistants in VEConfigure to soften the overload response, or adjusted the PowerControl settings? I've seen mention of tweaking the "overload trip time" but I can't find a definitive answer on whether that's actually exposed for the MultiPlus II or just the older units. Also wondering if staggering the loads with a simple timer relay on the kettle socket would be a reasonable workaround rather than faffing with the firmware.

Would love to hear if anyone's cracked this — or if I'm missing something obvious.

Reply by Dizzy60:

@VanMark Sounds frustrating! A few things worth checking — first, have a look at your battery's BMS discharge current limit. Even if the cells themselves can handle it, a lot of Gobel BMSs are set fairly conservatively out of the box and will pull the plug before the MultiPlus even breaks a sweat.

Also worth checking your DC cable sizing and connections. Voltage sag under load can trigger the low voltage cutoff even with a healthy battery — poor crimps or undersized cable are surprisingly common culprits.

What does VEConnect show in the logs when it trips? The alarm history should tell you whether it's overcurrent, low DC voltage, or temperature related. That'll narrow it down considerably before you start changing settings blindly.

Had this exact issue on my narrowboat setup last year — MultiPlus II 48/3000 tripping under kettle loads.

Worth checking your Low DC Cutoff voltage setting in VEConfig. Mine was factory default and the BMS on my Fogstar cells was briefly pulling voltage down under sudden high-draw spikes, triggering the inverter's protection before the BMS even had chance to respond properly.

Also — battery cable sizing and connections. I'd run what I thought was adequate cabling but under 2500W+ loads the voltage drop at the terminals was enough to cause grief. Went up to 70mm² and the problem disappeared almost entirely.

@Dizzy60 has likely covered the BMS comms side, but even without full VE.Bus/CAN integration you can often resolve it purely through voltage threshold tweaking in VEConfig.

Had the same drama with my van build — turned out my BMS was throwing a strop and sending a premature low-voltage signal to the Victron before the cells were actually struggling, classic case of the BMS crying wolf. 🐺

Check your BMS communication settings in VictronConnect — if you've got DVCC enabled and the BMS is chatting nonsense over VE.Bus, the MultiPlus will obediently shut itself down mid-brew like a well-trained butler. Absolute nightmare when you just want a cuppa.

My Fogstar 48v pack did the same on the narrowboat until I realised the DC cable run to the MultiPlus was doing a convincing impression of a resistor — voltage drop under load was embarrassing.

Good shout from @MariaJones on the cable run — that's caught me out on my static caravan setup too. Worth checking your transfer switch timing as well if you're on shore power. The MultiPlus II has an AC input current limit setting in VEConfigure that's easy to overlook — if it's set too low it'll throttle the inverter before it even tries to pull from the battery properly.

Also, what's your charge current set to on the BMS side? If the cells are sitting at a slightly low state of charge, even a momentary kettle spike can push the inverter into protection mode before the BMS has chance to react sensibly.

Download VictronConnect and watch the live data while it trips — the history tab will usually tell you exactly which protection kicked in.

Ran into this exact scenario in my motorhome last summer. Before you go chasing cables or the BMS, pull up the VictronConnect app and check your MultiPlus II's event history — it'll tell you why it tripped rather than having you guess.

Mine was showing an overtemperature fault, not undervoltage at all. The unit was tucked in a poorly ventilated locker and cooking itself under kettle load. Five minutes with a jigsaw cutting a proper vent panel sorted it completely.

Also worth checking your charge/discharge limits programmed in the BMS match what Victron expects to see. If the BMS is set conservatively and cuts comm with the MultiPlus mid-draw, it'll shut down hard every time.

Don't overlook the simple stuff before diving deep into wiring. The app logs are your best mate here.

Seconding what @Geordie said about VictronConnect — the history graphs are gold for diagnosing this.

One thing nobody's mentioned: check your AC output wiring too, not just DC side. Had a loose neutral on my garden office setup that caused identical random trips under load. Looked fine visually but was arcing slightly under current draw.

Also worth checking the transfer switch settings in VEConfig — if PowerAssist is misconfigured it can behave weirdly on sudden load spikes like a kettle.

Hey @VanMark, one thing worth checking that I haven't seen mentioned yet — your BMS communication with the MultiPlus II. If you're not running a DVCC setup with proper BMS comms (via VE.Bus or CAN), the inverter won't know the battery's actual limits and could be hitting a conflict between what it thinks it can pull and what the BMS is actually allowing. Had almost identical behaviour on my 48v system until I sorted the BMS-to-Cerbo link properly. Worth confirming your charge/discharge current limits are configured correctly on both ends. What BMS are you running with those Gobel cells?