A car's battery cannot charge if it is not installed in a car. Even when it is in a car, the alternator does not fully restore a battery's charge; it helps maintain a battery in good health, but after a while, the charge of a battery can deplete, especially when using a lot of electrical components. A battery can also drain by sitting idle in a car not being used or by being stored on a shelf. Charging a battery is best using a lower amperage setting over a longer period of time.
Make a jumper cable for the battery charger. Do this by cutting a two-foot length of the 6-gauge insulated battery cable with the wire cutters. Strip each end of the insulation from the cable about a half inch down with the wire stripper. Crimp an alligator handle at each end of the cable using a pair of pliers.
Clean the terminals of the battery with a battery terminal cleaner. This will scrape off old corroded lead and expose new lead on the battery terminal for optimum connection.
Put on the safety glasses and set the battery charger settings to 12 volts (some battery chargers may offer different volt settings).
Set the battery charger amp setting to two, six or 12. The lower the amp setting, the longer you should allow it to charge. Refer to the owner's manual of the charger for the time and amp ratio. A higher amp setting is acceptable if you want to charge the battery quickly.
Set the battery type setting to "conventional" (if applicable).
Set the battery on a shelf, floor or table as far away from the charger as the length of the clamp wires of the charger will allow.
Connect the red alligator clip of the battery charger to the positive battery terminal post. There will be a "+" stamped on the battery housing near the terminal post indication the positive post location.
Connect the black clip of the battery charger one of the clamps of the jumper cable you made. Connect the other end of the jumper cable to the negative battery terminal post. This post will display a "-" on the battery housing.
Plug the charger into the electrical outlet. Some charger models will power up immediately while other models may have a power button or a timer switch to activate electrical power to the charger.
Allow the desired amount of time to charge the battery indicated by the time and amp ratio in the owner's manual of the charger.
