The ability to run household appliances off 12-volt batteries is useful for over-the-road truck drivers to tailgate chefs at a weekend football game. The magic comes through a power inverter, which can plug into your car's cigarette lighter. While they come in many sizes, most inverters cost under £65 and are available at any hardware store. So, the next time camp with the family, don't feel like you have to rough it. Bring your laptop and espresso machine.
Determine which power inverter to buy. If you're buying it specifically for one appliance---say, a refrigerator--check out the tag on the back of the refrigerator to find its wattage rating. Small refrigerators need around 60 to 100 watts. If your appliance only shows an amperage rating, multiply this number by 110. This gives you wattage. Buy an inverter with a rating slightly larger than your wattage needs.
Plug your inverter into your vehicle's cigarette lighter or a 12-volt charger outlet. Usually, inverters rated 400 watts or less have this type of plug. For bigger inverters, hardwire the inverter with cables hooked directly to the battery. Use at least a 4-gauge wire for lengths up to six feet, and 2-gauge for anything over that. Attach the cables to the battery using ring terminals, available at any auto parts store.
Plug your appliance into the inverter and turn it on. Depending on your battery and the wattage of your appliance, your battery can run down in as little as an hour. Deep cycle marine batteries generally have a higher reserve power rating, last longer, and can withstand repeated recharging.
Increase your power potential by wiring two batteries "in parallel," doubling your charge time. Simply wire the two positive terminals together, and the two negative terminals together to effectively create one battery. Use a surge protector if you're plugging in more than one appliance.
While 12-volts won't hurt you, 110 volts can kill. Don't let your inverter get wet, and never operate it inside an engine compartment. Operate it on a flat surface, in a well-ventilated area, out of direct sunlight.