There is no best battery maintainer -- only a battery maintainer that makes the most sense for your specific situation. We've selected the Battery Tender Plus charger and maintainer as our top model, and it's certainly a great pick, but if you want something for a different price, or with a different amp range or selection of safety features, you may opt for something else. You'll also need a different charger if your vehicle doesn't have a lead-acid battery, and you may opt for something less powerful if you drive a smaller vehicle (like a motorcycle).