A: Check the battery state of charge by visually inspecting the indicator eye on the top of the battery and performing an open voltage circuit test with a digital voltmeter. Disconnect the negative Battery Cable first, then the positive cable and perform a battery load test with a load tester. If the battery is weak or defective, the tool will indicate this condition immediately. If replacing the battery, make sure to get one that is identical with the same dimensions, amperage rating, cold cranking rating, etc. Installation is the reverse of removal, connecting the positive cable first and the negative cable last.