Make sure to connect the red wire to the positive terminal of your battery and the black wire to the negative terminal. Once battery is connected, plug the charger into a 110V power source. Charge only sealed lead acid type batteries. Connecting other battery types can cause personal injury or property damage. Do not reverse polarity of the battery charger leads. Do not let battery charger leads make contact with one another while connected to a battery as this can cause personal injury or property damage.