How to Use an Automotive Battery Charger

An automotive battery charger is made to charge a standard lead-acid automotive battery. These are the typical 12 volt types found in virtually every automobile. They all have a positive, or red battery terminal, and a negative, or black, battery terminal. Every automotive battery charger has corresponding charging cables that must be attached correctly. Connecting these charging cables correctly to these terminals is the key to successful and safe battery charging.

• 1

  Put on a pair of safety goggles. These are the kind that wrap around your eyes for full protection from any dirt, debris or battery acid.

• 2

  Open the hood of your vehicle and locate the battery. If the battery is out of the vehicle, place it on a level surface.

• 3

  Attach the positive cable to the positive terminal on the battery.

• 4

  Attach the negative cable to the vehicle itself. Any piece of metal will work, such as a frame member, a bumper or an engine-supporting bracket. Do not attach the negative cable to the negative battery terminal. Alternately, if the battery is out of the vehicle, run a jumper cable from the negative side of the battery as far as possible, then connect the battery charger to the jumper cable.

• 5

  Adjust the battery charger to charge a 12 volt battery, if applicable, on chargers that have voltage settings. On chargers with amp rate settings, set the amperage rate to whichever setting is desired. Most amperage rates are variable between 2 and 30 amps. A 2 amp setting will trickle-charge the battery and may take eight to 20 hours for a full charge, depending upon how depleted the battery is. A 30 amp setting will power-charge the battery in as little as one hour but may blow breakers at the breaker box. A good average setting is 10 amps, which will fully charge the battery in only a few hours and will be compatible with most fuse and breaker boxes.

• 6

  Stand away from the charger and plug it into a grounded wall socket. The built-in ammeter will register the charging function, and when the ammeter goes down to zero, the battery is charged.

• 7

  Unplug the charger when finished and turn the battery charger off. Remove cables that are connected to either the battery terminals or the jumper cables.