How to Wire an Inverter to a Battery Safely
By Frank Zale · August 7, 2026 · 3 min read
Wiring an inverter is where van builds get serious, because an inverter pulls more current than anything else in the system. Do it right and it's simple: thick cable, a big fuse close to the battery, and a solid ground. Do it wrong and you get voltage drop, tripping, or a fire. Here's the safe way.
Why the inverter is special
A 2,000W inverter running near capacity pulls about 165 amps from a 12V battery. For comparison, your fridge pulls 3–4 amps. That enormous current is why the inverter gets its own heavy cable and a large fuse — normal appliance wiring would melt.
The wiring, step by step
- Mount the inverter close to the battery. Shorter cable = less voltage drop and less copper cost. Keep it ventilated.
- Size the cable to the current. Use the inverter's continuous wattage ÷ 12V to get amps, then pick the gauge from an ampacity chart. A 2,000W unit needs very thick cable (often 2/0 AWG for short runs). The wire gauge calculator does this exactly.
- Fuse the positive at the battery. A fuse (ANL/MEGA class) within a few inches of the battery positive, rated to protect the cable. This is the most important safety component in the whole van.
- Ground it well. Run the negative back to the battery/negative bus bar with equally thick cable.
- Torque every lug. High current + a loose connection = heat. Use proper crimped lugs and torque them.
Sizing the fuse
The inverter fuse protects the cable, so size it to the cable's ampacity (above the inverter's max draw, below the wire's limit). Get this from the wire & fuse guide — never run a big inverter unfused.
Match it to your battery
A big inverter is useless if the battery can't supply the current or store the energy. An induction cooktop through a 2,000W inverter drains a 100Ah battery in under an hour. Size the battery bank and cable to the inverter, not the other way around — the free calculator keeps them consistent.
Hard-wired vs plug-in
Small inverters (≤600W) can run from a fused 12V socket. Anything bigger must be hard-wired directly to the battery with proper cable and fusing — never through a cigarette socket.
FAQ
What size cable do I need for an inverter?
Size it to the inverter's maximum current (watts ÷ 12V) using an ampacity chart. A 2,000W inverter can pull ~165A and needs very thick cable over short runs — use the wire gauge calculator.
Do I need a fuse between the battery and inverter?
Absolutely — a large fuse within a few inches of the battery positive, sized to protect the cable. It's the single most important safety part in the system.
Can I plug a big inverter into a 12V socket?
No. Only small inverters (≤600W) suit a fused socket. Larger inverters must be hard-wired directly to the battery with heavy cable and a proper fuse.