Equipped with premium monocrystalline solar cells, the Renogy 10-Watt Solar Battery Charger Maintainer manages your 12-Volt lead-acid battery in daylight conditions by converting the sunlight into usable electricity and maintaining a healthy state of charge. The built-in MPPT (Maximum Power Point Tracking) charge controller intelligently manages the charging process and improves the charging efficiency by 10% to 20%. The plug-and-play SAE connecter and included adapter cables make the solar battery charger maintainer a versatile fit for most applications. Note: for some makes or models of vehicles, the cigarette lighter port may not operate when the ignition is turned off. In such cases, please connect the solar battery charger maintainer to the battery directly.