This thing is a total "piece". I was so excited that I had this great device when my wife's car battery died. So, I plugged it in and started charging. 10 minutes later, I tried to start the car with no luck. The battery on her car wasn't even that dead, as the a/c, radio, headlights, and all the lights still worked. I kept it plugged in for another 20 minutes - total 30 minutes now. Still no start. I borrowed jumper cables from a nearby motorist - the car started immediately.
So, I get home and start reading reviews and learn that several news stations have targeted this device and tested on there programs with several different cars at different stages of being dead. It failed every test. An auto expert on one the shows said "I have yet to see one of these work."
What a POS.