If you’re looking for the easiest way to maintain your battery’s charge, take a look at Battery Tender’s Solar Maintainer. Battery Tender is a well-known brand that you can find in brick-and-mortar stores and make both solar and plug-in battery chargers.
Unlike some of the other products on our list, this battery maintainer is waterproof, sparkproof, and includes built-in temperature compensation, so it doesn’t damage your battery during extreme high or low temperatures. Other solar chargers must be kept inside (on a car dash, for example). Battery Tender’s product can be safely left outside 24/7, so you don’t need to worry about bringing it inside during rain or snow.
Their Solar Maintainer comes in 5 watt, 10 watt, and 15 watt models and includes both an integrated blocking diode so it doesn’t leach power from the battery at night as well as a charge controller so it doesn’t overcharge and damage your battery – both key components of any good solar battery maintainer.
This product has over 700 reviews, with the vast majority giving a perfect 5-star rating. Customers report the charger is extremely durable and many have left it outside for months on end without issues.