Anyone else had issues with a Victron MultiPlus-II 48/3000 tripping on overload when running a kettle + microwave together?

We've been off-grid on our smallholding in mid-Wales for about 18 months now, running a 48V system with a 560Ah lithium bank and a 3kW array. The MultiPlus-II 48/3000 has been absolutely solid until recently — now it's tripping on overload pretty much every time I try to run the kettle (2.2kW) and microwave (900W rated, but apparently pulls closer to 1.5kW on startup) at the same time. That's only around 3.7kW combined, and the inverter is rated for 3kVA continuous with a 6kVA surge, so in theory it should cope.

I've updated the firmware via VE.Config and checked the AC out wiring — all looks fine. The battery voltage is sitting at a healthy 52–53V under load, so I don't think it's sagging to the point of triggering the low voltage cutoff. The tripping happens almost instantly when both loads kick in together, which makes me think it might be a settings issue rather than a hardware fault. The overload trip level in VE.Config is currently set to the default — I haven't touched it.

Has anyone adjusted the overload trip delay or threshold on theirs, or is there something obvious I might be missing? Also wondering whether the assistants (PowerAssist etc.) could be interfering somehow, though we're not connected to the grid out here so that seems unlikely. Any thoughts welcome.

@ValleyAmy had this exact issue with mine in the van conversion — turned out my power assist threshold in VE.Configure was set too conservatively. Worth checking your "AC input current limit" and whether PowerAssist is actually enabled, because by default it can be quite cautious about drawing from the battery to supplement loads.

Also — what's your DC cable sizing between the battery and MultiPlus? I found a marginal connection was causing voltage sag under combined spike loads, which triggered the overload protection before PowerAssist could even kick in.

A kettle + microwave together is easily 2.8–3.2kW at startup, so you're right at the edge of what the 3000 can handle without proper settings. Some people step up to the 48/5000 for kitchen-heavy setups.

Hey @ValleyAmy, worth checking a couple of things beyond what @OddJobBob22 mentioned. Your kettle alone is likely pulling 2.8-3kW, so adding even a modest microwave pushes you well over the 3kVA continuous rating — the MultiPlus-II isn't keen on that even briefly.

Have a look at your overload trip delay setting in VEConfigure — you can sometimes squeeze a bit more tolerance in there. Also check your AC output current limit; I've seen these set conservatively from the factory.

Longer term, a kettle on a timer so they can't overlap is the easiest fix honestly. Some folks swap to a lower wattage travel kettle (1kW) which makes a massive difference. If you're regularly running both together you might genuinely be bumping up against the limits of that inverter size rather than a configuration issue. What's your DC cable sizing like? Voltage sag under load can trigger trips too.

LiFePO4Pro | ⚡ 847 posts | Powys

@ValleyAmy one thing nobody's mentioned yet — check your AC input current limit in VEConfigure if you're still connected to any grid or generator input. If it's set too low, the MultiPlus can get confused about how much power assist to provide and trips rather than compensates properly.

Also worth checking: what's the state of charge when this happens? A lithium BMS pulling back current under load can look like an overload to the inverter even when your cells are healthy. If you're running Victron Smart Lithium or similar, check whether the BMS comms are properly configured in DVCC — a mismatch there can cause exactly this behaviour.

What firmware version are you on? There were some known quirks pre-v490 with sudden load spikes.

Yeah, had similar on my static. Kettle + microwave is a killer combo — both have high inrush current on top of their running draw, so they spike well beyond their rated wattage for a split second at startup.

What actually sorted mine was staggering them by just a few seconds. Sounds obvious but genuinely works. Kettle first, let it settle, then hit the microwave.

Also worth checking if your transfer switch is set too sensitive — mine was flipping to inverter mid-kettle-boil when it shouldn't have been, which confused the overload logs completely.

If you're on VRM, pull the detailed log around the trip time and look at the AC load graph — you'll see the exact spike that caused it rather than guessing.

Foggy | ⚡ 312 posts | Derbyshire

@ValleyAmy one thing worth trying is staggering your loads slightly — stick the microwave on first and then flick the kettle on once it's running. The microwave's inrush hits hardest in that first split second, so if both are starting simultaneously you're stacking two inrush spikes right on top of each other. Even a 5-second gap makes a noticeable difference in practice.

Also, what's your battery temperature like? Cold LiFePO4 cells can limit discharge current quite aggressively depending on your BMS settings, which effectively reduces what the inverter can pull during those peak moments. Worth checking your BMS logs if you can — might tell an interesting story. 🙂

RhysPalmer | ⚡ 203 posts | Brecon Beacons

@ValleyAmy fellow mid-Wales off-gridder here! One thing I'd add that hasn't been mentioned — have a look at your PowerAssist settings in VictronConnect. If you've got any AC input connected (generator perhaps?), PowerAssist can sometimes behave oddly and cause unexpected trips rather than smoothly boosting.

Also worth checking the overload trip curve setting. The 48/3000 has a degree of configurability there — mine was set overly sensitive from factory defaults and I had it tripping on my washing machine before I adjusted it.

That said, combined draw of a 3kW kettle and a 1.2kW microwave is genuinely pushing right up against your inverter's rated continuous output, so even with everything optimised you might just be at the limit realistically. A 48/5000 might be worth considering longer term.