After having a bad experience with a no-name charger (very slow: after 4 hours still not completely charged) for my Nokia mobile, this one charges as fast as the original ACP-12 home charger (little more than one hour).It has a hidden green power LED.If that isn't lit, turn on your ignition (duh). If it still isn't, check the fuse of your 12V outlet, as mine had been blown by the previous car owner!