Anyone else finding 12V systems genuinely limiting once you go beyond ~400W of solar?

Running a 48V Victron system in my shepherd's hut build (MultiPlus-II 48/3000, Cerbo GX, 4x Fogstar Drift 12V 200Ah in series) and honestly can't imagine going back. The wire gauge savings alone are significant — running 6mm² cable where I'd have needed 35mm²+ at 12V for the same power levels.

What prompted this post: a mate is planning a motorhome conversion and insisting on 12V "for simplicity." He's spec'd 600W of Renogy panels and a 200Ah lithium bank, and I've been trying to explain that at those kind of numbers the efficiency losses and cable costs start to eat into any simplicity argument. His inverter loads will hit 2kW occasionally (induction hob, short bursts) — at 12V that's 170A+, which means serious busbars, fuse sizing headaches, and expensive cable runs.

Has anyone got a good real-world comparison, or successfully talked someone into 24V or 48V for a vehicle build? Curious whether the 24V middle ground is actually worth it for motorhomes specifically, or whether it's just delaying the inevitable jump to 48V.

BurnKen | 847 posts

@Charlie1981 Completely agree on the wire gauge point - it's the thing people overlook until they're actually trying to run decent cable runs. I went 48V on my outbuilding setup for exactly that reason; the difference in cable costs alone nearly paid for the voltage conversion.

One thing worth mentioning for anyone reading who's on the fence - the Fogstar Drift cells in series do require a bit more attention to balancing than a native 48V pack would. Not a dealbreaker by any means, just worth keeping an eye on your cell-level monitoring through the Cerbo. Had a slightly lazy cell drift on mine after about 8 months that I'd have missed without it. The VRM portal catches it nicely though.

KangooAdventure | 312 posts

On the narrowboat I ran 12V for years and the penny dropped when I started adding more panels — suddenly I was running 70mm² cable everywhere and still seeing voltage drop on long runs to the bow. Switched to 48V via a Victron Multiplus-II and the difference was night and day. Thinner cable, less heat, less lost energy.

The other thing nobody mentions: fusing becomes far more manageable at 48V. At 12V with serious loads you're speccing some genuinely frightening fuse ratings.

@Charlie1981 curious how your Fogstar cells are balancing in that series configuration — I've heard mixed reports about keeping four packs in harmony long-term without active balancing. My setup uses a proper 48V Fogstar Drift 200Ah unit rather than stacked 12V, which sidesteps that headache entirely.

HalfAJob53 | 312 posts

@Charlie1981 @BurnKen The wire gauge thing is obviously a big deal but what sold me on 48V was the efficiency losses at higher currents on 12V. Running anywhere near 2kW on 12V and you're pushing 166A - the I²R losses are genuinely painful, and that's before you factor in the voltage sag under load. Moved my workshop setup to 48V last spring and the difference in how the batteries actually behave under heavy draw (table saw, dust extractor simultaneously) was immediately obvious. Still see people insisting 12V is fine "because it's simpler" but once you're doing anything serious it really isn't the easier option anymore - it's just more familiar.

Spider85 | 1,204 posts

@Charlie1981 @HalfAJob53 One thing nobody's mentioned yet - component availability and pricing has shifted massively in the last couple of years. When I built my first 48V system back in 2019 you were really hunting around for decent kit at sensible money. Now the Fogstar Drifts, the SOK batteries, even budget MPPT controllers from Victron's lower range - it's all just there and the price points are reasonable. That psychological barrier of "48V feels complicated" has basically dissolved for anyone willing to do a bit of reading. I'd also add that if you're planning any kind of inverter above 1500W, trying to do that cleanly on 12V is just asking for trouble with voltage sag under load. Learned that the hard way before I made the switch. 48V all day for anything serious.

CoastalCruiser | 847 posts

Good thread this. I'd add that the 48V vs 12V debate often gets framed purely around efficiency and wire gauge, but there's a practical safety angle worth considering too. Working on a 12V high-current system with 400W+ of panels means you're dealing with some seriously chunky fault currents. My previous 12V setup had a short that made the cable glow before the fuse did its job - genuinely alarming. At 48V your currents are quartered for the same power, which makes proper fusing and protection far more manageable in practice.

@Spider85 makes a fair point on components - I'd also say the 48V lithium market has matured enormously in the last couple of years, so the premium over 12V equivalents has largely disappeared now if you shop sensibly.

Shunt_Guy | 847 posts

@Charlie1981 Completely agree on the wiring - but the thing that really shifted my thinking was battery management simplicity. With 12V and high currents you're constantly fighting voltage drop across connections, and every dodgy crimp or slightly undersized busbar becomes a genuine problem. Move to 48V and your currents drop to a quarter, which means your BMS, fusing, and cabling all have far more headroom. I've seen so many 12V builds where the owner's chased a mystery fault for weeks and it turned out to be accumulated resistance across multiple connections under load. Less of an issue at 48V. That said, for truly minimal builds - a small van, a weekend bothy - 12V still makes sense. The ecosystem of cheap 12V accessories is hard to beat at low power levels.

Jonno88 | 312 posts

Worth flagging something practical that's bitten a few people I know - if you're running any 12V native appliances (certain water pumps, some lighting circuits, older 12V TVs etc) on a 48V system, you'll need a proper DC-DC converter rather than just assuming you can tap off part of the battery bank. Learned this the hard way watching someone damage their cells through uneven discharge. The converters are dead cheap nowadays though, so it's genuinely not a dealbreaker. @Charlie1981 how are you handling your 12V loads in the shepherd's hut?

DerekMoore89 | 203 posts

Lurking on this thread because I'm mid-planning a narrowboat build and genuinely torn. My current motorhome runs a basic 12V setup with about 300W Renogy panels and it's fine for my needs, but the narrowboat is a different proposition entirely - I'm looking at 600W+ and potentially running an induction hob occasionally.

At what point does the 48V conversion actually make financial sense given the inverter/charger premium? Is the Victron MultiPlus-II 48V noticeably pricier than the equivalent 12V unit when you factor in the battery configuration complexity?

CopperRoamer | 89 posts

@DerekMoore89 snap - I'm also mid-narrowboat planning and this thread is doing my head in (in a good way)! Currently pencilling in a 48V system with Victron kit but the number of 12V appliances on narrowboats is genuinely awkward, isn't it? Diesel boilers, bilge pumps, navigation lights... do you just run a Victron Orion DC-DC converter to a separate 12V bus? That's what I'm leaning towards. Anyone actually running this dual-bus setup on a boat specifically? Curious whether the Orion handles the occasional high-draw spikes from bilge pumps without any drama.