Your camper's electrical system runs on 12 volts, but plenty of household appliances (a laptop, a coffee machine, a hairdryer, a specific charger) run on 220 volts through a standard plug socket. The bridge between those two worlds is the power inverter: a device that converts your battery's 12 V into the 220 V that comes out of a wall socket. Knowing how to choose one right stops you buying too small (and finding your appliance won't work) or too big (and wasting money and space).
What an inverter actually does
The inverter takes the 12 V direct current from your auxiliary battery and turns it into 220 V alternating current, the same as comes out of the sockets at home. That lets you use household appliances without being plugged into a campsite's mains. Important: the inverter doesn't generate energy, it only converts it. Everything you plug in comes out of your battery, so its consumption is your consumption.
The key figure: power rating
Inverters are rated in watts (W), and you should choose one based on the most power-hungry appliance you'll run at any one time. Check the wattage of your appliances:
- Charging a laptop, phone, a small TV: 300-600 W is more than enough.
- Small appliances (a blender, a tool charger): 600-1000 W.
- Heavy-draw appliances (hairdryer, filter coffee machine, microwave): 1500-2000 W or more.
Watch out for appliances that generate heat (hairdryer, toaster, kettle): they use a huge amount of power. Using them while not plugged into mains power can drain your battery in minutes. Sometimes it makes more sense to skip them than to build a huge installation just for them.
Pure sine wave vs modified sine wave
This is the technical difference that matters most. There are two types of inverter:
- Modified (or square) sine wave: cheaper. Fine for simple things (a light bulb, a basic charger), but can cause problems or noise with sensitive electronics, motors and modern chargers.
- Pure sine wave: reproduces power just like the mains at home. Works with everything, including delicate electronics (laptops, medical equipment, some chargers). Costs more, but it's the recommended option if you're plugging in anything beyond a light bulb.
For a camper where you're charging a laptop and other devices, a pure sine wave inverter is worth the extra cost.
Installation and safety
The inverter connects directly to the battery with a good-gauge cable (it carries a lot of current) and its own protective fuse. Fit it close to the battery, well ventilated, and don't oversize it just because: a large inverter left switched on also draws some power simply by being active. Cable gauge and fuses need the same care we covered in installation mistakes.
In short
Choosing the right inverter means sizing the power to your most demanding appliance, going for pure sine wave if you're connecting electronics, and fitting it with the right cable and fuse close to the battery. The one thing to do today: list which 220 V appliances you'll actually want to use and their wattage; if nothing draws heavily, a 600-1000 W pure sine wave inverter will be more than enough. And remember everything you plug in comes out of your battery: work out your autonomy.
