My lawn mower ran out of power. tested it with my multimeter to find out the exact voltage level. and this turd after plugging it in said my battery is fine and fully charged? I kept trying to plug it in and it did NOT charge my lovely but LOW battery. I threw that piece of junk aside and hooked up an AMERICAN MILWAUKEE car charger to the battery and it started charging immediately and in about an hour. I wanted a smaller, lighter charger that was easier to connect and use on my lawn tractor, but what I got was total crap. Your mileage may vary. but mine stalled trying to use this piece of crap as it claimed to be able to charge the battery. It will not read the correct voltage and will not charge a dead battery.