Beginner Van Electrics: One Battery, a Fuse Box, and Not Burning Anything Down

(you don't need the London Underground diagram to start)

You search "van electrics" hoping for a shopping list. What you get is an infographic with three battery banks, a Cerbo GX, something called a MultiPlus inverter, and a "DC-DC charger" — all wired together in a diagram that looks like the London Underground map, before you've even bought a battery. So you close the tab and go back to sleeping on an air mattress with your phone charging off a USB block plugged into the cigarette lighter.

I want to close that gap. Because the distance between what's online and what you actually need for your first few weekends away is enormous. You can start small. You should start small. Here's how.

What a minimal setup actually is

Three things. That's the whole core.

• A leisure battery — stores your power. It's separate from your starter battery so that a weekend of running lights and a fridge can't leave you unable to start the engine on Sunday night.
• A fuse box — splits power out to your individual circuits, and the fuses stop a faulty cable from turning into a fire.
• A split charge relay or B2B charger — tops the leisure battery back up while you drive, off the engine's alternator.

That's it. Solar is optional. Hook-up is optional. You can run a perfectly good weekend van without either and add them later when you fancy it.

The four mistakes beginners make

This is the bit that matters. Get these wrong and you get dead batteries, intermittent gremlins, or — at the worst end — a fire.

1. No fuse at the battery. This is the big one. A fuse protects the cable, not the device. The fuse box protects everything from the fuse box forward — but the fat cable running from your battery to the fuse box has no protection of its own. That cable runs through your van, behind panels, near metal. If it chafes through and shorts, there's nothing to stop it, and a leisure battery can push hundreds of amps into a dead short. Fit a fuse — ANL or a big blade type — within 300mm of the battery positive terminal. If you do one thing in this guide, do this.

2. Using a car battery instead of a leisure battery. They look almost identical. They are not the same animal. A car (starter) battery is built to dump one big burst of current to crank the engine, then get topped straight back up. Slowly draining it over an evening of lights and a fridge will wreck it in weeks. A leisure battery is designed for exactly that slow, deep discharge. Don't be tempted by the cheaper starter battery on the shelf.

3. No earth bar — daisy-chaining your negatives. Every device's negative should run back to a central earth (negative) bus bar, and then a single cable goes from that bar to the battery negative. The temptation is to chain them — fridge negative to light negative to battery — but every join adds resistance, and you end up with flickering lights and faults that move around and drive you mad. An earth bar costs about £8 and deletes the entire problem.

4. Undersized cable on the main run. The cable from battery to fuse box carries everything. Size it for what you might eventually run, not just today's two LEDs. 10mm² handles most weekend loads comfortably and leaves you room to grow. 6mm² is fine for very light use. Don't use the thin bell-wire stuff from the car accessories aisle for your main run — it can't carry the current and it gets hot.

What to buy — the minimal kit

Honest UK prices:

• 100Ah AGM leisure battery: ~£100. Fine for weekends. If the budget stretches, a 100Ah lithium at ~£280 is the better long-term buy (see the full electrical guide for why).
• 6–8 way blade fuse box: ~£15–£25
• ANL fuse holder + 100A fuse for the battery-to-fuse-box cable: ~£10
• 10mm² cable, enough for your run: ~£2–£3/metre
• Earth bar / negative bus bar: ~£8–£15
• Simple split charge relay: ~£20. One caveat: if your van has a smart alternator (most post-2015 vans do), a basic relay won't charge properly and you need a DC-DC charger instead — the full guide covers this.
• Ring terminals, connectors, cable ties: ~£15–£20

Total: roughly £180–£200 for a working weekend setup. Less than most people expect.

I'm not going to walk you through the physical wiring crimp by crimp — for that, 12 Volt Planet and MKGT have excellent step-by-step diagrams that are clearer than anything I'd draw here.

Adding to it later

Here's the reassuring part. Nothing above locks you in. This setup is built to grow:

• Add solar: bolt a panel to the roof, put an MPPT controller between panel and battery. Done.
• Add hook-up: fit a shore power inlet and a mains charger to top up on campsites.
• Upgrade to lithium: disconnect the AGM, connect the lithium. The rest of the system stays exactly as it is.
• Add more circuits: your fuse box has spare ways. Add loads as you add gear.

Starting simple doesn't mean starting wrong. It means starting.

When you're ready for more

If you're planning a proper permanent conversion — solar, hook-up, lithium sizing, inverters and load management done properly — read the full van electrical guide. That's where Victron, battery sizing and real system design live. This guide is the one you read first. That one's for when you've caught the bug.