Updated: 23 September 2026 · EuroVan Shop
In short: A 12V campervan wiring diagram puts the leisure battery at the centre, with a fuse and isolator right next to it, then bus bars that connect a DC/DC charger from the starter battery, an MPPT solar controller, a mains charger or inverter-charger, and the 12 V distribution box. The VANPOWER kit includes the full diagram with cable sections.
Get the kit with its wiring diagramWhat does a 12V campervan wiring diagram show?
A campervan wiring diagram shows how every component connects to the leisure battery, which protection sits on each cable and, in a complete diagram, the cable section of each run. It is the plan you wire from, and the document an inspector or electrician will ask to see.
The logic is the same in almost every van: one battery in the middle, charging sources coming in, consumers going out, and protection at the battery end of every cable. This guide describes that logic block by block, in words. It deliberately gives no cable sections or fuse values: those depend on your currents and cable lengths.
If you want a ready diagram, the VANPOWER kit comes with a detailed wiring diagram with cable sections, a step-by-step tutorial and a wiring guide PDF in English, French and German, matched to the exact parts in the box. See all campervan electrical kits.
The campervan wiring diagram at a glance
Read the diagram from the battery outwards: each block below connects to the bus bars, and the bus bars connect to the battery through the main isolator and fuse.
| Block | Connects | Role | Protection (general) |
|---|---|---|---|
| 1. Leisure battery | Centre of the system | Stores the energy | Main fuse and isolator as close to the battery as possible |
| 2. Bus bars | Battery to every device | Common positive and negative connection points | Each device on its own fused cable |
| 3. DC/DC charger | Starter battery to leisure battery | Charges while driving | Fused at each battery end, isolator on the circuit |
| 4. MPPT solar controller | Solar panels to leisure battery | Charges from the sun | Isolator on the solar circuit, fused battery cable |
| 5. Mains charger or inverter-charger | Hook-up to leisure battery (and 230 V sockets) | Charges on hook-up; inverter makes 230 V | Fused battery cable; 230 V side by a qualified electrician |
| 6. 12 V distribution box | Bus bars to switch panel and consumers | Feeds lights, fridge, pump, fan, USB | One fuse per circuit |
Step 1: how do I wire a leisure battery?
The leisure battery connects to the rest of the system through a main isolator switch and a main fuse, fitted as close to the battery terminals as possible. Nothing else should be connected directly to the battery posts.
The isolator lets you cut all power for work or storage; the fuse protects the main cable against a short circuit. In the VANPOWER kit the battery isolator switch (12 to 48 V, 275 A continuous, M10 studs) sits on the battery circuit, and the terminal lugs and fuses pack provides the MEGA fuses, resettable fuses and lugs, sized to the inverter power you choose.
The LiFePO4 battery has a built-in BMS that protects it against overcharge, short circuit and deep discharge, and it needs M8/M6 terminal hardware. The BMS pauses charging below 0 °C to protect the cells; it discharges down to −20 °C.
LiFePO4 leisure battery
12.8 V, 100, 200 or 314 Ah, built-in BMS, Bluetooth monitoring.
Battery isolator switch 275 A
12 to 48 V ON/OFF switch, M10 studs, used three times in the VANPOWER kit.
Terminal lugs and fuses pack
Lugs, MEGA fuses and resettable fuses, sized to your inverter.
Step 2: bus bars, the hub of the circuit
Bus bars are the junction points of the diagram: one positive and one negative bar collect every device, so the battery only carries two main cables. They keep the wiring tidy and make it easy to add a device later.
Every charger, the inverter and the distribution box land on the bus bars, each through its own fuse. All negatives return to the negative bar. When you read a diagram, follow the positive path (battery, fuse, isolator, bus bar, device fuse, device) and check that no device bypasses its protection.
Step 3: alternator charging with a DC/DC charger
Yes, running the engine charges the leisure battery once a DC/DC charger links it to the starter battery. The charger's input comes from the starter battery side and its output goes to the leisure battery through the bus bars, with protection at each battery end.
The Victron Orion-Tr Smart 12/12-30A delivers up to 30 A (40 A peak) with a 3-stage charge (bulk, absorption, float) and suits AGM, GEL and lithium batteries. Engine-running detection switches it on only when the alternator is charging, so it never drains the starter battery when parked. As a rough estimate, one hour of driving at full output puts up to about 30 Ah back into the battery. In the VANPOWER kit, an isolator sits on this alternator circuit.
Older vans used a split charge relay here; for a lithium battery a DC/DC charger is the better choice. See DC/DC charger vs split charge relay.
Victron Orion-Tr Smart 12/12-30A
DC/DC charger, up to 30 A, engine-running detection, Bluetooth.
Victron SmartSolar MPPT 100/30
MPPT solar controller, up to 440 W of panels at 12 V, Bluetooth.
Step 4: solar panels to the MPPT controller
Solar panels never connect straight to the battery: they feed an MPPT charge controller, and the controller's battery output goes to the bus bars through a fused cable. The controller sets the correct charge voltage for your battery type.
The Victron SmartSolar MPPT 100/30 accepts up to 440 W of panels on a 12 V system and charges at up to 30 A; in the VANPOWER kit it is specified for 300 to 500 W of panels. An isolator on the solar circuit lets you cut it for maintenance. The kit tutorial gives the connection order; follow it and the Victron manual. To size the array, see how many solar panels you need. EuroVan Shop does not sell panels.
Step 5: hook-up with a mains charger or an inverter-charger
On hook-up, the battery is charged either by a separate mains charger or by the charger built into the inverter. Which one appears in your diagram depends on whether you need 230 V appliances.
| Diagram | Mains charging | 230 V sockets |
|---|---|---|
| Without inverter | Victron Blue Smart IP22 12V 15A to the bus bars | None (or hook-up only) |
| With inverter | 20A charger built into the inverter | Powered from the battery, or from hook-up through the automatic bypass |
With the inverter, the automatic bypass means that when you plug into campsite power, the inverter passes hook-up power to your appliances and recharges the battery at the same time, with nothing to switch. The inverter's 12 V side lands on the bus bars through its own fuse, sized to its power.
We do not give instructions for the 230 V side (hook-up inlet, inverter AC wiring, sockets). Have any 230 V installation carried out or checked by a qualified electrician.
Step 6: 12 V distribution box and switch panel
The distribution box takes one feed from the bus bars and splits it into separately fused circuits for each consumer: lighting, fridge, water pump, roof fan, USB sockets. The switch panel then turns those circuits on and off.
The VANPOWER kit uses a 12 V distribution box with a 5-gang switch panel with USB; the VANPOWER SMART kit uses a connected distribution box (fuse holder plus switches you control from your phone). Give the fridge its own fused circuit: a VANCOOL 50 L compressor fridge draws 25 to 30 W in use. If you also want the fridge on mains without using the battery, the 230V to 12V converter comes with a 1/2/OFF selector so the fridge only draws from one source at a time.
Cable sections and fuse ratings: where to find them
Cable sections and fuse ratings must be calculated from the current each cable carries and its length, so no generic article can give you the right values for your van. Undersized cable heats up; an oversized fuse will not protect it.
- With the VANPOWER kit: every cable section is on the wiring diagram, and the fuses are supplied, pre-sized to your inverter.
- With your own layout: have the cable sections and fuses sized by a qualified person, using the component manuals.
- Always: fuse each positive cable at its source end, fit isolators near the battery, crimp lugs properly and keep the 12 V cables short.
Free technical support is included while you install the kit: contact our team.
What are the wiring rules for campervans?
The rules depend on your country and on whether you register the vehicle as a motor caravan, so check your national rules (DVLA/VCA in the UK, TÜV in Germany, RDW in the Netherlands) before you start. Keep your wiring diagram with the vehicle papers.
The components of the VANPOWER kit are ECE R10 certified. Any 230 V installation should be checked by a qualified electrician.
VANPOWER kit
Complete 12 V / 230 V system, wiring diagram with cable sections, PDF in EN/FR/DE.
VANPOWER SMART kit
Same system and diagram, with switches controlled from your phone.
Not sure how to size your 12 V system?
Send us your appliances and how you travel (weekends, several days, full time). Our France-based technical team answers within 24 hours and can build a custom kit.
Ask our technical teamFrequently asked questions
How do I wire a leisure battery to my campervan?
Connect it through a main fuse and isolator fitted close to the battery, then to positive and negative bus bars. Chargers, inverter and the 12 V distribution box connect to the bus bars, each with its own fuse, following a diagram with cable sections.
How do you wire a campervan electrical system?
Battery first, with its main protection; then the bus bars; then the DC/DC charger from the starter battery, the MPPT solar controller, the mains charger or inverter-charger, and finally the 12 V distribution box and switch panel.
Does running the engine charge the leisure battery?
Yes, if a DC/DC charger or split charge system links the two batteries. The Victron Orion-Tr Smart 12/12-30A charges at up to 30 A and only switches on when the engine is running.
What cable size do I need for campervan wiring?
It depends on the current and length of each cable, so it must be calculated for your layout. The VANPOWER wiring diagram gives every cable section; otherwise have them sized by a qualified person.
Is there a campervan wiring diagram PDF?
Yes. The VANPOWER kit includes a detailed wiring diagram with cable sections, a step-by-step tutorial and a wiring guide PDF in English, French and German.
Skip the calculations: the VANPOWER kit comes pre-sized, with its wiring diagram and free technical support.
See the VANPOWER kit
