Campervan Wiring Diagram and Step-by-Step Guide

Campervan electrical wiring diagram

This original planning diagram shows the protected power paths and the order of the major components. It deliberately omits site-specific wire gauges and fuse values. Those depend on the equipment manual, continuous current, surge behavior, cable length, insulation rating, bundling, ambient temperature, and local requirements. It also omits chassis bonding, equipment grounding, AC protective devices, and shore-power wiring because those details depend on the inverter, charging equipment, vehicle, and applicable code. Do not use this drawing as a grounding or AC wiring plan.

Download the printable SVG wiring diagram. Print at landscape orientation and keep it with the equipment manuals while laying out the system.

Diagram bill of materials

The mental model: power flows through the battery

Everything in a van system connects to the battery, but not directly. Charging sources (solar, the alternator) push power in, and loads (lights, fridge, inverter) pull power out. Between them sit two simple hubs called bus bars, one positive and one negative, plus fuses to protect every wire. Get that picture and the rest is just connecting parts in the right order.

The parts, from battery outward

1. The battery

A 12V LiFePO4 battery is the standard for vans. It is the bank that stores all your energy. Mount it securely so it cannot move while driving, and keep the terminals accessible.

2. Main fuse and battery shutoff

Right at the positive battery terminal, install a main fuse (often a Class T or ANL fuse) and a battery disconnect switch. The fuse protects the main cable, and the switch lets you kill all power for service or storage. This is your most important safety hardware.

3. Positive and negative bus bars

Run one heavy cable from the battery positive (through the main fuse) to a positive bus bar. If the system uses a battery monitor, run the battery negative to the battery side of its correctly rated shunt, then connect the shunt's system side to the negative bus. Every load, charger, and other system negative must land after the shunt. Now every other part connects to the bus bars instead of fighting for room on the battery terminals.

4. The charging sources

Two common ways to refill the battery:

• Solar: panels on the roof feed a charge controller (MPPT is standard), and the controller feeds the bus bars. Never wire panels straight to the battery. See our charge controllers guide.
• Alternator (DC-DC charger): a DC-DC charger takes power from the engine's starter battery while you drive and safely charges your house battery. It is the fastest way to refill on travel days.

5. The loads

Two kinds of loads pull from the bus bars:

• DC loads (lights, fridge, fans, USB, water pump) connect through a fused distribution block. Each circuit gets its own fuse sized to its wire.
• AC loads (laptop charger, blender, anything with a wall plug) run from an inverter, which converts battery DC into household AC. Choose pure sine wave.

The order to build it

1. Mount the battery, main fuse, disconnect switch, and both bus bars. Leave the battery disconnected.
2. Add the charge controller and wire it between panels and bus bars (panels last).
3. Add the DC-DC charger if you are using alternator charging.
4. Add the DC fuse block and wire your 12V loads, each on its own fuse.
5. Add the inverter on its own heavy, fused cable to the bus bars.
6. Double-check every fuse and connection, then connect the battery last.

Building in this order means the system is never live while you are still adding parts, which is far safer.

Recommended gear

The simplest way to avoid mismatched parts is to follow a proven parts list. Our Classic 400W RV and van build lists every component, the battery, MPPT controller, DC-DC charger, inverter, and a wiring kit, in compatible sizes, with the wiring order explained. For a smaller rig, see the minimalist van build, and to tailor it to your van use the Solar Calculator. Want the panel, controller, and roof wiring already matched in one box? Compare our campervan solar kit picks.

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As a concrete example, these are the four core parts from that 400W build, already sized to work together:

• Solar: 2x Renogy 200W mono panels
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• Battery: 12V 200Ah LiFePO4 battery with a BMS rated for 200A continuous discharge (many 200Ah units ship a 100A BMS, which cannot feed a 2000W inverter; check the spec sheet)
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• Charge controller: Victron SmartSolar MPPT 100/30
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• Inverter: Renogy 2000W pure sine wave inverter
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This is not a complete bill of materials. The main fuse, bus bars, disconnect switch, fuse block, and cable all still need to be sized to your wire runs and loads, exactly as covered above.

Commissioning checklist before the battery goes live

1. Confirm the house battery is disconnected and every removable branch fuse is out.
2. Trace positive and negative conductors against the diagram. Check polarity with a meter instead of relying on cable color alone.
3. Confirm every fuse is appropriate for the protected wire and does not exceed the equipment manual's specified maximum.
4. Verify cable lugs, bus bars, shunt, and equipment terminals are tightened to the manufacturer's torque specification and protected from accidental contact.
5. Check for unintended continuity between the positive and negative buses. Follow the inverter manual's precharge procedure if it requires one.
6. Connect the battery, close the main disconnect, and energize one branch at a time while watching for heat, odor, abnormal voltage drop, or fault indicators.
7. Test charging sources separately before combining them, then verify the battery monitor sees both charge and discharge current in the correct direction.

Related guides

Choose your AC loads before sizing the cables. Our campervan inverter sizing guide connects appliance demand to continuous output, startup loads, and battery draw.

• 12V vs 24V vs 48V Off-Grid Systems
• How to Size an Off-Grid Solar System
• Off-Grid Solar Explained

Engineering references

• Victron Energy: Wiring Unlimited, including DC fuses, disconnects, shunts, bus bars, mobile installations, and grounding.
• Blue Sea Systems: circuit protection and conductor-sizing case study.
• Off-Grid Field Guide DC wire gauge chart, with the formula, ampacity constraints, and worked inverter example used by this diagram.