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Short answer: if you're building a standard campervan — Sprinter, Transit, Promaster — stick with 12V. Every van appliance runs on 12V natively. Going 24V only pays off when you're pulling over 3000W through an inverter or running 400Ah+ battery banks where 12V current gets ridiculous.
Here's what actually changes between the two. At 2000W, a 12V system draws 185A — that needs 50mm² (1/0 AWG) cable and a 250A fuse just on the inverter run. The same 2000W on 24V? Only 92A, so 25mm² (4 AWG) cable works fine. You save on copper, you save on weight, and voltage drop is halved at every connection point. But — and this is the catch — your alternator is 12V, so you need a DC-DC boost charger. And every 12V device (fridge, fans, lights, USB) needs a 24V-to-12V step-down converter.
⚡ Expert tip
If you're on the fence, look at your inverter size. Under 2000W, 12V is a no-brainer — the wiring is manageable and everything is plug-and-play. Over 3000W, go 24V to keep cable sizes sane. That 2000-3000W middle ground? I'd still lean 12V unless you're also running 400Ah+ of batteries.
Example calculation for your setup
Results based on a typical use case
| Appliance | Power | Usage/day | Wh/day |
|---|---|---|---|
| Compression fridge | 45W | 24h | 1080 |
| LED lighting | 20W | 4h | 80 |
| Water pump | 30W | 0.5h | 15 |
| Phone charging | 15W | 2h | 30 |
| Daily consumption | 1205 Wh | ||
Recommended LiFePO4 battery
126 Ah
(80% depth of discharge)
Recommended AGM battery
201 Ah
(50% depth of discharge)
Recommended solar panels
302 Wc
4h average sun hours
Recommended inverter
No 220V appliances — no inverter needed
Adjust these values with the calculator below
VANPOWERCALC PROYOUR ENERGY PROFILE
YOUR ENERGY PROFILE.
This document contains the sizing of your future electrical installation, calculated based on your appliances.
Minimum Daily Consumption
0 WH / DAY
Inventory:
SYSTEM SIZINGPage 2
Battery
To guarantee 0WH without damaging your bank (80% max discharge):
0 AH
LiFePO4 12V
Solar
Minimum power required to recharge your consumption:
0 W
via MPPT
220V AC
Maximum power (with 25% safety margin).
0 W
No Need
Safety & CablingPage 3
12V Cable Sizing Guide
Use this professional reference table to select the correct gauge (mm²) for your cables. For 12V in a van, the maximum tolerated voltage drop is 3%. Always use multi-stranded flexible automotive wire.
| Current (A) | Round trip < 2m | Round trip 4m | Round trip 6m |
|---|---|---|---|
| 5A (LEDs, USB) | 1.5 mm² | 2.5 mm² | 4 mm² |
| 10A (Fridge, Pump) | 2.5 mm² | 4 mm² | 6 mm² |
| 20A (Heater) | 4 mm² | 10 mm² | 10 mm² |
| 50A (DC/DC Booster) | 10 mm² | 16 mm² | 25 mm² |
| 100A (Inverter) | 25 mm² | 35 mm² | 50 mm² |
Fuse Sizing
The fuse protects the wire, not the appliance. Always place it as close to the power source as possible (battery or busbar).
- Wire 1.5 mm² → Max fuse 10A
- Wire 2.5 mm² → Max fuse 20A
- Wire 4 mm² → Max fuse 30A
- Wire 6 mm² → Max fuse 40A
- Wire 10 mm² → Max fuse 60A
SCHÉMA ÉLECTRIQUE
PANNEAUX SOLAIRES
0W
REGULATEUR MPPT
BATTERIE AUXILIAIRE
0 Ah
Lithium LiFePO4
FUSIBLE
FUSIBLE
BOÎTE À FUSIBLES 12V
Pompe, Leds, Frigo...
CONVERTISSEUR 220V
NON REQUI
PRO GEARPage 4
SHOPPING LIST
Where to find this equipment? Here is the community-approved selection.
12V 6-way Fuse Box
Mandatory protection
Digital Multimeter
Test your connections
Heavy Duty Crimping Tool
For perfect lugs
Heat Shrink Tubing
Insulation and safety
GENERATED BY VANPOWERCALC PRO - UNLIMITED.
About this tool
I've done both. My Sprinter build is 12V with 300Ah LiFePO4 and a 2000W inverter — works great for normal vanlife. The cable run to the inverter is heavy (50mm², about 1.5m each side) but manageable. On a box truck conversion I helped with last year, we went 24V because the owner wanted a 3000W inverter for an induction cooktop and a small AC unit. In 12V that would've meant 278A continuous — you'd need 70mm² cables and a 350A fuse. In 24V it was 139A, much more reasonable with 35mm² cable. The tradeoff was needing a Victron Orion 24|12-20 step-down for the Dometic CFX fridge, the MaxxFan, and all the LED strips. Added about $250 and another point of failure. For vans under 25 feet, I'd say 12V every time unless you have a specific high-power need.
Frequently asked questions
Can I run both 12V and 24V in my van?▼
Absolutely. Plenty of truck campers and skoolies do this. You wire your battery bank at 24V for the inverter and heavy loads, then use a DC-DC step-down converter (like the Victron Orion 24|12-25, around $150) to power your 12V circuits — fridge, lights, fans, USB. It adds one component but gives you the best of both worlds.
Is 24V more efficient than 12V?▼
At the same power level, yes — slightly. Lower current means less resistive loss in the cables (I²R losses). On a 2m cable run at 100A in 12V, you lose about 2-3% to heat. At 50A in 24V carrying the same power, losses drop to about 0.5-0.8%. Over a year of daily use, that can add up to a few hundred Wh saved. Not life-changing, but not nothing.
Can my van alternator charge a 24V battery bank?▼
Not directly. Van alternators output 12-14.4V. You need a DC-DC boost charger like the Victron Orion-Tr Smart 12|24-15 (~$220) to step up the voltage. This is an extra cost and component that 12V systems don't need.
What van appliances don't work on 24V?▼
Most standard van gear is 12V only: MaxxFan, most Dometic/Engel fridges (some have 12/24V models but they cost more), Chinese diesel heaters, water pumps, LED strips. You'll need a 24V-to-12V converter for all of these. The Dometic CFX series does come in a 12/24V version, but it's $50-100 more than the 12V-only model.
Do solar panels care about 12V vs 24V systems?▼
Not really — if you're using an MPPT charge controller. MPPT controllers accept a wide input voltage range (up to 75-150V depending on model) and convert it to whatever your battery voltage is. You can wire panels in series for higher voltage regardless of your battery bank voltage. The panels themselves don't change. The only difference is your charge controller's output setting: 12V or 24V nominal.