How to Wire a House Battery in a Van or RV
Wiring a house battery correctly is the foundation of a safe van electrical system. Here's the step-by-step process.
What you're building
The house battery sits in a secured location. Two cables — main positive and main negative — connect it to your electrical panel (bus bars). Everything else in the system connects to the bus bars, not to the battery directly.
Battery (+) → [ANL Fuse] → [Disconnect Switch] → Positive Bus Bar
Battery (−) → [Shunt] → Negative Bus Bar
Tools and materials
- Battery (LiFePO4 recommended — see battery guide)
- Main positive cable: 2/0 AWG welding cable, length = battery-to-bus-bar distance + extra for routing
- Main negative cable: Same size as positive
- ANL fuse holder + ANL fuse: Rated for your system (150A for most builds without inverter; 200A–300A with 2,000–3,000W inverter)
- Battery disconnect switch: Blue Sea Systems 9005e 300A or similar
- Ring terminals (lugs): 2/0 AWG, correct stud hole size for your battery terminals (typically 5/16" or 3/8") and bus bar studs
- Hydraulic crimper for the large lugs
- Positive and negative bus bars
- Battery monitor shunt (if installing Victron SmartShunt or BMV)
- Battery box or securing hardware
Step 1: Secure the battery
Mount the battery in its location — battery box, secured shelf, or dedicated compartment — before wiring. The battery must not be able to slide or tip in a collision. Use a battery hold-down strap, L-brackets, or a purpose-built box.
Step 2: Determine cable lengths
Measure your routing path from the battery to the bus bar location — don't take the straight-line distance, account for routing around obstacles. Cut both cables slightly long; you can always trim excess, but a short cable means a reroute.
Step 3: Crimp lugs onto cable ends
Crimp ring terminals onto both ends of both cables. For 2/0 AWG cable, you need a hydraulic crimper — see how to crimp battery cable lugs for the full process.
Cover each crimp with adhesive-lined heat shrink.
Step 4: Install the ANL fuse and disconnect switch (positive cable)
The positive cable sequence: battery terminal → ANL fuse (within 18" of battery) → disconnect switch → positive bus bar.
Install the ANL fuse holder first, as close to the battery positive terminal as the routing allows. The fuse protects the entire positive cable run — it must be close to the source (battery), not near the destination.
Install the battery disconnect switch between the fuse and bus bar.
Leave the ANL fuse out for now — work with the circuit de-energized.
Step 5: Install the shunt (negative cable)
If installing a battery monitor: the shunt mounts in the negative cable. The shunt has two terminals — one labeled "BATTERY" (toward the battery negative terminal) and one labeled "LOAD" or "AUX" (toward the negative bus bar and loads).
Connect a short cable from battery negative to the "BATTERY" terminal of the shunt. Connect the main negative cable from the shunt's "LOAD" terminal to the negative bus bar.
Important: After installing the shunt, ALL loads and charging sources must connect to the negative bus bar — not directly to the battery negative. Current bypassing the shunt gives inaccurate readings.
Step 6: Route and secure cables
Route both main cables from the battery to the electrical panel. Use split wire loom to bundle them. Secure with cable clamps every 18 inches. Keep cables away from sharp edges; install rubber grommets at any metal penetrations.
Step 7: Connect to bus bars
Attach the positive cable (from the disconnect switch) to the positive bus bar's main stud. Attach the negative cable (from the shunt's load side) to the negative bus bar's main stud.
Torque the stud nuts — ring terminals should be firmly clamped and not rotate under hand pressure.
Step 8: Install ANL fuse and power up
With all connections made and verified, install the ANL fuse into the holder. This energizes the positive cable up to the disconnect switch. The disconnect switch should be in the OFF position.
Verify with a multimeter: positive bus bar reads battery voltage when disconnect is ON, reads zero when disconnect is OFF.
Step 9: Add charging sources and loads
Now connect your solar MPPT controller, DC-DC charger, inverter, and fuse block to the bus bars — following each component's own installation instructions with their own appropriately sized fuses.