Guide · power
12V or 48V for a Van? And Should the Inverter Stay On?
Published August 4, 2026 · Last verified August 4, 2026
Three questions turned up together in the van electrical threads we collect this cycle, and they are the same question asked from three directions. Should I buy an all-in-one or build from components? Should I go 48V because the battery deals look better there? Should I leave the inverter on all the time?
The first one we have already answered at length in power station or DIY battery bank. This guide covers the layer underneath it: the system voltage you build the bank at, and whether the inverter hanging off it ever gets switched off.
This is a community-evidence guide, per How We Test. VanTested has not bench-measured an inverter’s idle draw or built a 48V system. Every figure below is a published comparison, a manufacturer claim, or an owner report, and it is labeled as one.
Why the 48V question is being asked at all
It is usually not asked on engineering grounds. It gets asked because of pricing. As one builder put it in an all-in-one versus component thread: “I saw that the best deals for batteries which also integrate well with solar are the 48 volt batteries” (u/Longjumping_Ad_8175).
That observation is accurate, and it is worth understanding why. The 48V battery market is shaped by home solar storage, which buys in far greater volume than the van market does, so cost per usable watt-hour at 48V is genuinely better and the gap is not small. The mistake is treating that as the whole calculation. A battery is one line on a bill of materials. Choosing its voltage decides the wiring, the charging, the protection and the availability of every other component in the van.
What 48V actually buys you: copper
The real argument for 48V is current, and it is arithmetic rather than opinion. Power is volts times amps, so for a given wattage, four times the voltage means a quarter of the current — and cable size is set by current, not by power.
The figures published in build comparisons make the point better than any explanation:
| Inverter | System voltage | Approximate current draw | Typical cable |
|---|---|---|---|
| 1,500W | 12V | ~125A | 1/0 AWG on a 20 ft run |
| 1,500W | 48V | ~31A | 8 AWG |
| 3,000W | 12V | ~250A | 4/0 AWG even on a short run |
| 3,000W | 48V | ~62A | 4 AWG |
These are published figures from build guides rather than our own measurements, and real cable sizing depends on run length, temperature and how conservative your voltage-drop budget is. Our wire gauge calculator will run your actual numbers.
The cost consequence is the part people underestimate. 4/0 welding cable is roughly wrist-thick and priced in the region of $8 to $12 a foot; 4 AWG runs closer to $1.50. On a 15-foot battery-to-inverter run that is something like $150 of copper against $25. And it is not only the cable — fuses, busbars, switches, lugs and crimping tools all scale with current, and 250A-rated hardware is a different price class and a different physical size from 60A hardware.
There is a second effect that matters more in a van than people expect. Voltage drop is proportionally brutal at 12V. A 1V drop in a 12V system is an 8.3% loss; a 2V drop is 16.7% and leaves you at 10V, below what plenty of 12V electronics will tolerate. The same 2V drop on a 48V system is about 4%. Long runs are simply easier to get right at higher voltage.
What 48V costs you: the van is 12V
Here is the counterweight, and for most builds it is decisive. Almost nothing in a van is a 48V device.
House lights, compressor fridges, roof fans, water pumps, diesel and propane heater controllers, cellular hotspots, USB outlets, and every 12V air conditioner on the market are all built to take 12V. So are the vehicle’s own systems, which is where alternator charging has to interface. A 48V bank does not remove that requirement, it just moves it: you now need a 48V-to-12V DC-DC converter sized for the whole 12V half of the van, and everything downstream of it depends on one box.
That is the hybrid architecture most premium 48V campers actually use — a 48V bank feeding the inverter and the heavy loads, stepped down to a 12V bus for everything else. It works. It also means:
- One more component, one more price, one more failure point. And it is not a peripheral failure point. If that converter dies, the fridge, the lights, the fans and the water pump go with it.
- A narrower parts market. 12V van components are stocked everywhere and troubleshooting them is a solved problem with a thousand forum threads behind it. The 48V mobile ecosystem is thinner, and more of the good gear is built for a house rather than a vehicle.
- Charging complexity. Alternator charging into a 48V bank is a different and generally more expensive proposition than the 12V DC-DC chargers most builds use.
None of that makes 48V wrong. It makes it a system decision rather than a battery purchase, which is the thing the pricing-led version of the question skips over.
Where the cutover actually is
Strip away the tribalism and the decision comes down to how much current your worst-case load pulls:
| Your build | Honest answer |
|---|---|
| Fridge, fans, lights, laptop, occasional small AC load | 12V. 48V is a conversion tax with nothing to show for it |
| Adds a 1,000–2,000W inverter used intermittently | Still 12V for most people; check cable cost before deciding |
| Continuous inverter load in the low thousands of watts | The copper argument starts to bite — price both ways |
| Air conditioning plus induction cooking plus a big array | 48V bank with a 12V bus is the architecture to plan around |
| Any 12V air conditioner as the main climate load | 12V, and size it against the DC output ceiling, not watt-hours |
The trigger most build guides converge on is somewhere around a 3,000W continuous inverter. Below it, the DC-DC converters you have to add to serve the 12V half of the van eat the copper savings. Above it, 12V cable and protection get awkward to route and genuinely expensive.
One thing worth saying plainly: retrofitting the system voltage is not a small job. Changing from 12V to 48V later means new batteries, a new inverter, a new charge controller, new alternator charging and a step-down converter. This is one of the few decisions in a van build that is genuinely cheaper to get right on paper than to change in metal, which is a good reason to size for the loads you are actually going to add rather than the ones you have on day one.
The always-on inverter question
This lands in the same threads for a reason. An inverter left on is a continuous load, and continuous loads are what drive the whole architecture.
An inverter consumes power simply by being switched on, with no appliance plugged into it. Published idle-draw figures for typical units land somewhere around 10 to 40W, which is 240 to 960Wh across a full day. Owner reports of roughly 2A of idle current at 12V describe the same thing from the other end: about 48Ah over 24 hours.
Put that against a bank. A 100Ah 12V battery holds around 1,280Wh nominal, and you would not want to take all of it. An inverter idling at the high end of that range can consume a substantial share of a modest bank’s daily budget having powered precisely nothing. That is very often a larger number than the fridge everyone worries about.
Three things follow:
Bigger inverters idle harder. Idle consumption broadly scales with inverter size, so a 3,000W unit bought “for headroom” and left on has a standing daily cost that a 1,000W unit does not. Oversizing has a running cost, not just a purchase cost.
Eco mode is the specification that matters. Most current inverters offer an eco, standby or search mode: the unit sleeps and pulses the output looking for a load, waking when it finds one, which drops idle consumption close to zero. The catch is the search threshold. A low-draw device — a phone charger, an LED lamp, some laptop bricks — can sit below it and simply never wake the inverter. If you intend to leave the inverter on, the honest question is not “how low is the idle draw” but “does eco mode reliably wake for the specific things I plug in.”
The cheapest fix is a switch. If nothing in the van genuinely needs AC around the clock, a remote switch or a simple habit removes the problem entirely and costs nothing. And where something does need to run continuously, the better question is usually whether a 12V version of that device exists, because running it natively at 12V skips the inverter and its conversion losses altogether.
How the two questions connect
They are the same question. A build that genuinely needs an always-on inverter running real loads is a build with continuous high current, and continuous high current is exactly the condition where 48V starts paying for its complexity. A build that can switch the inverter off overnight almost certainly does not have the load profile to justify 48V.
So the order of operations is backwards from how it usually gets asked. Do not start with the battery deal. Start with the load list — what runs, at what wattage, for how many hours — put it through the battery sizing calculator, and let the worst-case continuous current pick the system voltage. The battery pricing follows the architecture, not the other way round.
What we would measure
Two things here are testable and neither has been tested by us or, as far as we can find, by anyone publishing numbers for the units van builders actually buy:
- Real idle draw against claimed idle draw, across a range of inverter sizes, and whether eco mode wakes reliably for a 5W, 20W and 60W load. Manufacturer idle figures are measured under conditions nobody documents, and the eco-mode threshold is almost never published at all.
- Real-world conversion losses through a 48V-to-12V converter under a typical van 12V load, which is the number the whole hybrid architecture argument turns on and which we have only ever seen quoted, never measured.
Both are on the bench list. Until then, treat every number on this page as what it is: a published claim or an owner report, useful for sizing a decision and not a substitute for measuring your own system.
Frequently asked questions
Is 48V better than 12V for a camper van?
Not in general, and the question is really about what you plug in rather than which is technically superior. 48V wins where current is the problem — big inverters, air conditioning, induction hobs, large solar arrays — because four times the voltage means a quarter of the amps and dramatically smaller, cheaper cable, fuses and busbars. 12V wins everywhere else, because the entire van appliance ecosystem is native 12V and a 48V bank has to convert down to serve any of it. For a build with a fridge, some fans, lights and a laptop, 12V is the right answer and 48V adds cost and failure points for no gain.
At what point does 48V start making sense in a van?
The practical trigger most build guides point at is a continuous inverter load in the low thousands of watts, or an all-electric build with air conditioning and induction cooking. Below about a 3,000W inverter, the copper savings do not cover the DC-DC converters you have to add to feed the 12V half of the van. Above it, the cable, fuse and busbar sizes at 12V start getting genuinely awkward to route and expensive to buy. If you are unsure, the cleanest test is to size the cable both ways for your actual worst-case load before you buy anything.
Can I run 12V appliances from a 48V battery bank?
Yes, but only through a 48V-to-12V DC-DC converter, and that converter becomes a single point of failure for the fridge, the fans, the lights, the water pump and the ignition-critical bits of the build. Most premium 48V camper systems are hybrids for exactly this reason: a 48V bank for the inverter and the heavy loads, stepped down to a 12V bus for everything else. It works well. It is also one more box, one more price, and one more thing that can leave you with a warm fridge.
How much power does an inverter use just being on?
Typical published idle-draw figures land somewhere around 10 to 40W depending on the unit and its size, which works out at roughly 240 to 960Wh over a full day. Put that against a 100Ah 12V bank, which holds about 1,280Wh, and an inverter left on all day can quietly eat a large fraction of it before a single appliance is used. Larger inverters generally idle harder than small ones, which is why oversizing an inverter has a running cost as well as a purchase cost.
Should I leave my van inverter on all the time?
Only if something genuinely needs AC around the clock, and even then check whether that device could run on 12V instead. If you do need it on, the specification that matters is a reliable eco or search mode — the inverter sleeps until it senses a load and wakes when something is switched on, which cuts idle consumption to near nothing. The catch is that low-power devices sometimes fail to wake it, so the search threshold has to suit your actual loads. Otherwise the simplest fix in the whole electrical system still applies: put a switch on it and turn it off.