I bought this to save and extend the life of the battery in my pickup truck. I live just outside of a very small town,about a mile and a half. A trip to town,a couple of stop(Post Office,grocery store,gas station)and back home,and I've started the engine three or four time and only put on as many miles. Not enough engine running time to re-charge the battery. After many times of not being able to start my truck and having to use a booster charger to start the truck,I finally needed a new battery. I hope this little charger will prevent this from happening again.(I will update if it fails).My only beef is the short power cord. I needed to buy a short heavy duty extension cord so as to be able to plug it in without having to open the hood each time.