I love the concept and carried one in my trunk for a long time. Problem was that it kept losing its ability to hold a charge, even though I was meticulous about discharging & recharging it. It worked fine in a few instances but then wouldn't hold a charge well enought to be of use. Of course I always have a good set of jumper cables on board but that's no use when you don't have a second vehicle.

Part of the value of these devices to me (and especially my wife) is the security factor: you don't have to be stuck on the side of the road or in a dark parking lot depending on the mercy of strangers.

I have searched all over the 'net and haven't found a brand of these things that is consistently reliable. If anyone here has better info I'm all ears!