didnt work.  left my key in and drained my battery .....tried this leaving it in for an hour...there are two lights one that glows green on good battery side...the other light does nothing on bad battery side...should at least glow orange til it charges and green when its charged.  this is a great idea buy if the electronics aren't useful you are better off with a jumper cable .  I had to borrow a jumper cable to start the vehicle.