Victron MultiPlus-II 24/3000 vs 48/3000 — worth going 48v for a motorhome build?

Right, so I'm finally pulling the trigger on the inverter/charger for my Fiat Ducato motorhome conversion and I've been going back and forth on this for weeks. I've got a 280Ah lithium bank (Fogstar Drift cells) and I'm trying to decide whether to build it as 24v or jump straight to 48v. The Victron MultiPlus-II 3000VA is available in both configurations and the price difference isn't enormous, but rewiring my whole DC system around 48v feels like a bigger commitment.

The main loads I'm planning to run are a 1200w induction hob, a small 12v compressor fridge (via a DC-DC converter), LED lighting, and occasional power tools when parked up on site. I'm not going to lie — the lower current at 48v is attractive for cable sizing alone, but most of the 12v accessories and solar charge controllers I already own are built around a 24v or 12v world.

I've done 48v on a static narrowboat install before and loved it, but that was a completely clean-sheet build with no legacy kit to worry about. The motorhome feels messier because I'm mixing habitation 12v stuff with the inverter loads.

Has anyone here made the jump to 48v in a vehicle build specifically? Did you regret keeping any 24v or 12v infrastructure, or did you just Orion-TR your way out of every problem?

@MarinePhil What's your total battery bank capacity in kWh though? Because 280Ah at 24v is only 6.7kWh, whereas 48v would give you 13.4kWh for the same Ah count — but I'm guessing you're not doubling your cells?

On my boat I went 24v partly because the wiring run lengths were short enough that the thicker cable wasn't a massive issue. In a Ducato you've presumably got a compact layout too?

The question I'd be asking is whether you're planning to expand the bank later. If yes, 48v makes the future upgrade path much cheaper per kWh. If it's a fixed 280Ah forever, is the 24v MultiPlus-II not perfectly adequate for your loads?

What's your peak draw likely to be — induction hob, air con, anything like that?

Hey @MarinePhil, one thing worth considering that nobody's mentioned yet — cable sizing. At 24v you're pulling roughly double the current for the same wattage, so you'll need beefier cabling between your battery and inverter, which adds cost and weight. In a Ducato where space is already tight, that can actually matter. The 48v system lets you get away with thinner, more manageable runs.

That said, if your solar charge controllers are already specced for 24v, switching voltage means replacing those too, so factor that into your overall budget. What panels and controllers are you planning to run? That might actually be the deciding factor here rather than the inverter itself. No point going 48v if your whole charging setup needs replacing to match.

Great points from @Squib30 on cabling — that's a real practical consideration people overlook.

One thing I'd add for a Ducato specifically: space and weight. The 48v setup typically means you're either doubling your cells or running them in series, and in a motorhome you're constantly wrestling with payload limits and cupboard space. If you're sticking with a single 280Ah bank, 24v is honestly fine for most motorhome loads — you're unlikely to be running anything that really stresses the system at that capacity.

The 48v argument becomes much more compelling once you're pushing 10kWh+ or running high-draw appliances regularly. For typical motorhome use — induction hob occasionally, fridge, lighting, charging devices — 24v will serve you perfectly well and keeps the build simpler. What's your heaviest regular load?