An automobile battery and charging system is designed so that the alternator recharges the battery automatically as the engine runs. This system works great almost all of the time, but when, for example, a car owner inadvertently leaves the lights on and the battery goes "dead," using the alternator to try to recharge the battery is not the right choice, as an alternator will likely overcharge and damage the car battery in this case. This is when you should recharge your battery with a battery charger.
Review the instructions and safety information for the battery charger before attempting to connect the charger to the battery. Make sure that the charger is unplugged and set to "OFF."
Identify the positive and negative terminals of the battery to be charged, as well as the positive and negative leads from the battery charger. The positive terminal will be denoted by a "+" symbol and may also be red, while the negative terminal will be denoted by a "-" symbol and may also be black. This also applies to the charger leads.
Attach the negative lead from the charger to the car frame, engine block or similar heavy gauge metal part.
Attach the positive lead from the charger to the positive terminal of the battery. You are now ready to charge the battery according to the manufacturer's specifications.
