The BatteryMINDer® Battery and Alternator Condition Tester (Model 12104) quickly checks the health of both your battery and alternator with the press of a button. Multicolored LEDs indicate battery voltage levels, and testing the alternator output is as simple as pressing the test button with the engine running. Suitable for all 12V batteries, it's waterproof and compact enough to mount on any battery. Installation is quick with two wire connections and included marine-grade Velcro, and it draws no power until activated.