I use something similar to this -
http://www.gadgets.co.uk/item/CARINV/12 ... erter.htmlI think mine came from Maplins, it has a built in sensor to prevent drainage of your car battery. The only problem I had was, as with most modern cars, the cigarette lighter (or Accessory Power Supply as they are now called!

) does not work when the car is switched off, so for £20, I had a local garage fit an 'APS' in the boot which is permanently live, allowing it to be used when parked up.
You can charge phones, razors, lap-tops, lamps, anything really. There are different sizes available, so if you intend running things off it, make sure you get one strong enough.
