An inverter turns your 12V battery into household AC so you can run mains appliances off-grid. It’s the component most people oversize, mis-size, or buy when they didn’t need one at all. This guide helps you decide whether you need an inverter, how big it should be, and how to wire it without melting anything.
Safety note — 12V wiring. An inverter is a high-current device. At 12V, a 2000W inverter can pull well over 150 amps from the battery — that demands heavy cable and a high-rated fuse mounted right at the battery terminal. Size the cable to that current and the run length, fuse at the source, and disconnect the battery before wiring. A charging battery vents hydrogen gas, so keep sparks away. Inverter wiring is unforgiving of mistakes; if you’re not confident with high-current DC, have an auto-electrician install it.
Do you even need an inverter?
Start here, because the answer is often no. An inverter only matters for AC appliances — things with a wall plug. If everything you run is 12V or USB (fridge, lights, phone, laptop charged from USB-C), you don’t need an inverter at all, and adding one just bleeds energy through conversion losses.
You need an inverter if you run:
- A laptop charged from its AC brick, power tools, or chargers with no DC option.
- Small kitchen appliances — and especially an induction cooktop.
- Medical devices like a CPAP that lack a DC input.
If your list is short and all-DC, skip the inverter and put the money into battery capacity.
How to size an inverter
1. Add up simultaneous AC loads
List every AC device you’d run at the same time and sum their wattage. Your inverter’s continuous rating must comfortably exceed that total. Sizing to the sum of everything you own — rather than everything you run at once — leads people to buy far more inverter than they need.
2. Account for surge
Motors and compressors draw a brief spike at startup — often several times their running wattage. A good inverter lists both a continuous and a surge (peak) rating. Make sure the surge rating covers your highest-spiking device, or it’ll trip when that tool kicks on.
3. Match it to your battery bank
A big inverter is useless without a battery to feed it. High-draw AC loads — induction cooking, air conditioning — don’t just need a large inverter, they need a large bank to sustain the load for any meaningful time. Run an induction burner for an hour and you’ll see hundreds of watt-hours vanish. Size the bank in the dual-battery system guide and confirm your charging can keep up via how much solar do you need.
What size do most overland rigs run?
A 2000W inverter is the common standard for overland AC demands — enough to handle laptops, chargers, and a small induction cooktop. Many builds use a combined 2000W inverter/charger, which both supplies AC and recharges the battery from shore power in one unit. The Battle Born 2000W inverter and inverter/charger are examples in this class.
That said, 2000W is not a default to copy blindly. If you only ever charge a laptop, a few-hundred-watt inverter is plenty. Size to your loads.
Pure sine vs modified sine
Buy a pure sine wave inverter. It produces clean AC that’s safe for sensitive electronics, motors, and medical devices. Modified sine is cheaper but can buzz, run motors hot, and upset some chargers and CPAPs. The savings aren’t worth the risk on gear that matters.
Wiring it safely
- Mount the inverter close to the battery to keep the high-current DC cable run short.
- Use heavy cable sized to the inverter’s maximum current draw and the run length.
- Fuse at the battery with a high-rated fuse or breaker within a few inches of the terminal.
- Switch it off when not in use — inverters draw idle current even with nothing plugged in.
- Disconnect the battery before wiring, and double-check polarity before powering up.
Common mistakes
- Buying an inverter you don’t need because all your gear is actually 12V/USB.
- Sizing to total owned wattage instead of simultaneous load.
- Ignoring surge, so the inverter trips when a tool or compressor starts.
- Undersized DC cable, which runs dangerously hot at high current.
- Skipping the source-end fuse on a circuit that can pull 150+ amps.
- Big inverter, small battery — the bank empties before you finish the task.
Bottom line
Decide if you need AC at all, size the inverter to your simultaneous load plus surge, buy pure sine, and back it with a battery bank big enough to sustain the draw. See the power hub to fit the inverter into your full system.