I agree that the cheap ones are junk, but there is another thing to think about.Different types of batteries have what I was told by a battery manufacture guy, is that different batteries have different full charge voltages, and that some tenders don't charge that high, and they will never cut off. Say type A battery has a charge voltage of 14 volts, and the tender only goes to 13.5, it will never see a full charge, and never shut off.