Victron MultiPlus 12/3000 vs 24v system — worth the faff of rewiring?

Currently running a 12v setup in the motorhome — 2x 200Ah Fogstar Drift LiFePO4 in parallel, fed by 400W of roof panels via a Victron MPPT 100/30. Works fine for most things but I keep tripping the inverter when I run the microwave and the induction hob at the same time. Looking at the MultiPlus 12/3000 to solve the surge problem, but someone at a rally last month told me I'd be better off jumping to 24v and fitting a MultiPlus 24/3000 instead.

The 24v argument makes sense on paper — thinner cabling, less heat, more efficient over distance. My cable runs to the back of the van aren't short either, probably 2.5m from battery to inverter. But I'm already into this 12v bank for decent money and I don't fancy binning it just to rebuild.

Has anyone actually done the 12v to 24v swap mid-build? I can rewire — done plenty of first fix and second fix in my time so the practical side doesn't scare me. It's more whether the real-world gains justify stripping half the van out. The solar side would need a rethink too since the 100/30 is 12v nominal.

What's the honest verdict — stick with 12v and get the bigger MultiPlus, or bite the bullet?

BazLewis72 | 847 posts | ⚡ Solar Addict

@ExChippie the cable sizing issue is where it gets painful with 12v at those loads. If you're running 3000W through 12v you're looking at 250A — your cabling and fusing costs alone start making 24v look very attractive very quickly.

The Fogstars are brilliant batteries but personally I'd seriously consider selling them and getting four in series-parallel for 24v rather than just bolting on a bigger inverter. Half the current means you can run much lighter cable runs throughout, and your MPPT efficiency improves too.

What's actually tripping — the inverter itself or a fuse/MCB somewhere? That might tell us whether it's a genuine capacity problem or just an undersized protection device that needs sorting first before you spend anything.

EcoFlowMaster | 203 posts | 🔋 Battery Botherer

@ExChippie genuine question before you go ripping everything out — what's actually tripping, the inverter or the fuse? Because I chased a "12v problem" for three weeks in my tiny house build before realising one of my

RussWebb | 64 posts | 🔌 Still Learning

Did exactly this migration on my static caravan last year — went from 12v to 24v with a MultiPlus 24/3000. The rewiring faff was probably a weekend's work but honestly the cable gauge difference alone made it worthwhile. Running thinner cables through tight spaces is so much easier.

One thing nobody mentioned to me beforehand — check your existing DC loads. I had a couple of 12v items that needed a Victron Orion DC-DC converter afterwards, which added unexpected cost.

What's actually tripping your inverter — is it peak draw or sustained load? That might change whether upgrading the system voltage even solves the problem, or whether you just need a bigger inverter on your existing 12v setup.

ForestDweller | 312 posts | 🌲 Off-Grid Tinkerer

Living aboard a boat with a 24v system here — the jump from 12v was absolutely worth it for me once I started running anything serious.

One thing nobody's mentioned yet: what does your existing alternator setup look like? If you're moving the motorhome regularly, rewiring for 24v means revisiting your DC charging too, not just the inverter side. A Victron Orion-Tr Smart 12-24 can bridge things if your vehicle alternator is 12v, but is that added complexity worth it for your usage pattern?

Also curious — what exactly are you tripping on? Sustained loads or peaks? Sometimes a MultiPlus-II 12/3000 with proper cable gauge solves the immediate problem without the full rewiring headache. What size cables are you currently running to the inverter?

Harry1965 | 147 posts | ⚡ Practical Off-Gridder

Done this exact swap on my cabin setup. The wiring faff is real but honestly the thicker 12v cables were more hassle long-term — every connection point is a potential voltage drop headache at those currents.

One thing nobody's mentioned: your Fogstar Drifts — check if they'll do 24v in series before committing. Some BMS configs don't play nicely that way. Worth a quick email to Fogstar support, they're usually pretty helpful.

Also budget for a new MPPT if you go 24v. Your 100/30 can handle 24v battery bank but you'll want to reconfigure it and double-check your panel wiring arrangement suits the new voltage.

For an EV charging setup specifically, 24v is the sensible direction of travel anyway — you'll want that headroom.

Curly7 | 847 posts | ⚡ Voltage Obsessive

@ExChippie the thing nobody mentions is that moving to 24v halves your cable losses, which on a motorhome install actually matters more than people realise — you're often running longer cable runs than you'd like. Your existing MPPT 100/30 handles 24v battery banks no bother, so that's one less thing to budget for.

The real question is what you're actually tripping on. If it's sustained loads like induction cooking or a decent inverter, 24v genuinely helps. If it's brief peaks from a kettle, sometimes just upsizing your cable and connections sorts it without the rewire headache.

What's your longest cable run from batteries to inverter? That'd help work out whether the voltage upgrade pays for itself in your specific setup.