Anyone else running a hybrid 12V/48V system in their van build?

Halfway through a van conversion and I've ended up in a bit of a weird situation. Started planning a standard 12V setup, then went deep on the rabbit hole and convinced myself 48V was the way to go for efficiency and thinner cable runs. Now I'm looking at running both — 48V bank for the main inverter/solar side, and a 12V bus (via a DC-DC converter) for lighting, USB, water pump, the usual low-draw stuff.

Currently eyeing up a Victron MultiPlus-II 48/3000 for the inverter/charger, with a Fogstar 48V lithium pack (or possibly building my own from 280Ah CATL cells). The 12V side would be fed through an Orion-Tr Smart 48-12/30. On paper it makes sense, but I'm wondering if the complexity starts working against you in a live-aboard or long-trip scenario when something inevitably goes sideways.

Has anyone actually built and used one of these split-voltage setups day-to-day? Particularly curious whether the Orion keeps up when you've got the pump, fridge fan and a load of 12V LED strips all kicking in at the same time — that's around 20A peak by my rough calcs. Or am I overcomplicating this and should just commit to one voltage and be done with it?

Lefty91 | 847 posts

@ShaunDixon Ha, classic rabbit hole situation! I ran a hybrid setup for about 18 months in my Transit before eventually consolidating to full 48V. Honestly though, the hybrid approach isn't as mad as people make out - loads of serious builds run exactly this.

The key thing I'd say is get your DC-DC converter sizing right from the off. I went too small initially and kept browning out my 12V side when running the compressor fridge and lighting simultaneously. Victron Orion-TR Smart is worth every penny for keeping the two banks playing nicely together.

What's your reasoning for keeping 12V elements? If it's just lighting and the odd USB charge, a decent step-down converter makes far more sense than a separate 12V bank. Would help narrow down the advice if you share more of what you're actually running.

ExpertCamper | 1,203 posts

@ShaunDixon I'm actually running something similar in my off-grid cabin setup — 48V bank for the heavy lifting (inverter, induction hob) and a Victron Orion-Tr 48/12-30 DC-DC converter feeding a separate 12V bus for lighting, USB charging, the 12V compressor fridge etc.

Works an absolute treat. The Orion is smart enough to handle it properly rather than just being a dumb dropper.

Key thing to watch: cable sizing on the 12V side still matters even though your loads are smaller, because you're stepping up current when you step down voltage. Caught a few people out on here before!

What's your inverter situation? If you're going Victron Multiplus on the 48V side, the whole ecosystem just clicks together nicely with Cerbo GX monitoring both buses. Makes the hybrid thing feel less "bodged" and more intentional 😄

MarineClare | 412 posts

@ShaunDixon My Victron Orion-TR DC-DC converter is basically the marriage counsellor keeping my 48V bank and 12V loads from filing for divorce. 💀