I have been using battery tender brand battery minders, saw these and decided to give them a try, as they were significantly less expensive. Was pleasantly surprised with the results, no low batteries over the winter.Am using a mixture of these and battery tenders on 15 cars, and 5 SxS's and 3 ATV's, all vehicles batteries and fully charged and start with a flick of a switch.If you want a lower cost option to battery tender, these work well.