Campervan Inverters: Running Mains Appliances Off-Grid

A 12V battery runs lights, fridges and USB, but it won't power a laptop charger, a coffee machine or a small TV. An inverter converts your battery's 12V into the 240V mains that UK appliances expect. It's the gadget that means you can work from a layby in Pembrokeshire or run a hairdryer at a festival without hunting for a hookup.

Pure sine vs modified sine

There are two types, and the difference matters.

• Pure sine inverters produce clean mains power, identical to the grid. Every appliance runs properly, including sensitive electronics like laptops and modern phone chargers. Expect to pay £150–£400 for a good one.
• Modified sine inverters are cheaper (£50–£150) but produce a stepped wave that can hum, overheat or simply refuse to run some devices — particularly anything with a motor or a switch-mode power supply.

For anything with electronics, buy pure sine. It costs a little more and saves a lot of frustration.

Sizing your inverter

Inverters are rated in watts. Add up the peak draw of everything you might run at once:

• Laptop charger: around 60–90W.
• Coffee machine: 800–1500W.
• Hairdryer: 1000–2000W.
• Small TV: 50–100W.

A 1000W pure sine inverter covers most people's needs and typically costs £150–£250. If you only need to charge a laptop and phones, a 300W–500W unit is plenty and much kinder to your battery.

Remember: an inverter draws from the battery at 10 times the current on the 240V side. A 1000W load pulls roughly 80A from a 12V battery — that drains a 100Ah leisure battery in little over an hour.

Wiring and batteries

The heavy current means thick cable, proper fuses and a decent battery. Run an inverter on an undersized battery and it'll sag or shut down mid-boil.

• Use cable rated for the current and keep runs short.
• Fit a fuse close to the battery terminal.
• A single 100Ah leisure battery runs modest loads; serious use needs a second battery or a lithium bank.

Pair your inverter with solar and you get close to fully independent power. That combination is covered in our campervan off-grid power article, and if you're still shopping for a van with good payload for the extra gear, see campervans for sale.