12V electrics: first fix and beyond

Think in paths, not gadgets

Draw where the battery, charger, fuse box, solar entry and main loads will live. Then draw the cable routes. First fix is running those routes while the van is open. Second fix is terminating, commissioning and labelling.

Cheap cable and random fuse ratings cause heat and mystery faults. Buy cable sized for the current, fuse for the cable, and keep positive and negative runs tidy and supported. A neat loom is not vanity. It is how you find a fault at the roadside without opening half the furniture.

First fix habits

• Glands wherever you pass through metal
• Extra length at terminations you might rework
• Label both ends as you pull
• Keep high-current runs short where you can
• Separate noisy chargers from sensitive data cables if you care about radio hiss
• Leave a pull-string in closed cavities for the cable you forgot

Photograph the open walls before cladding. Six months later you will not remember which rib hides the fridge feed.

Charging and batteries

Match the battery chemistry to the charger. Lead and lithium want different charge profiles. Size the DC-DC and solar for how you actually camp, not for a brochure fantasy of endless sunny days in Scotland in February.

If you run an inverter, treat AC like a proper circuit with RCD protection where required. Get qualified help for anything that feels out of your depth. Habitation electrical work often needs a competent person and paperwork for insurance and future sale. Budget for that.

Before you energise

Walk the diagram once more. Every cable should have a fuse you can name. Every battery connection should be protected against shorts. Then commission methodically: chargers first, then loads, then the awkward bits.

If you cannot explain the fuse for every cable, stop and redraw the diagram before you switch on.

Figures in this guide are planning estimates. Confirm weights and prices against real products, and have gas and electrical habitation work signed off by a qualified person.