Auto batteries are commonly known as lead-acid batteries. They are the oldest type of rechargeable batteries dating back to the mid-1800s. Lead-acid batteries are the preferred choice for automobiles as they are able to produce high currents at low voltages necessary to power starter motors. A typical auto battery only produces 12 volts but the...
M/F Discharge your battery so there's very little power left. Turn on electrical equipment in your car such as the heater-fan and lights. Don't turn on the engine as this charges the battery. Once discharged to the correct level, the lights will be dim and the heater-fan slow.
M/F Put on protective gloves and goggles before attempting to recondition your auto battery. The gloves protect you from electric shock and the goggles protect your eyes from any sparks that may occur.
M/F Position your auto so you're easily able to wire the battery cables from the charger. Open the hood.
M/F Remove the negative battery cable on your auto's battery using a wrench. The cable is colored black and the battery terminal labeled "-" or "neg." It's important you remove the negative cable first as this disconnects the power from your car.
M/F Remove the positive battery cable from the auto's battery using a wrench. The cable is colored red and the battery terminal labeled "+" or "pos." Move the cables away from the battery.
M/F Unscrew the caps from the six battery cells and check the fluid levels. Be careful --- the fluid is sulphuric acid and burns on contact with skin. The fluid should completely cover the cells. Each cell has a mark to indicate when it's full. Fill each cell with distilled water up to the mark on the cell. Replace the caps. Some batteries are sealed units so don't try to remove the cover: you'll invalidate your warranty.
M/F Place your battery charger close to battery. Attach the spring clamp on the end of the red positive cable from the charger to the positive terminal of the battery labeled "+" or "pos." Squeeze the clamp so it opens and place it firmly on the battery terminal then release the pressure. Twist the clamp slightly to ensure a good connection.
M/F Attach the spring clamp on the end of the black cable from your battery charger to the negative terminal of the battery labeled "-" or "neg" using the same method as on the red cable.
M/F Set the charger to its lowest charge setting. Many chargers have a setting called "trickle charge." If the charger has this setting, select it. The battery needs to be charged very slowly over a long time.
M/F Turn on the charger and check that it is charging. A light illuminates or the charger will have a display indicating the charge rate. Check that it is set to the lowest charge.
M/F Leave the battery to charge for 36 hours. Turn off the charger. Remove the two cables from the charger that are attached to the battery terminals. Don't reconnect the battery cables attached to the car.
M/F Use a voltmeter to check the voltage. Place the red prong from your voltmeter on the positive battery terminal and black prong from the voltmeter on the negative battery terminal. Read the voltmeter display. It should read "12 volts."
M/F Leave the battery disconnected overnight and then repeat the voltmeter test. If the meter reads "12 volts," it retained its charge and generally means your battery is reconditioned. If the voltage has decreased to less than 11 volts, your battery may not be retaining its charge. Check the voltage again after 12 hours. If it remains stable, your battery is fine but if it's reduced further you need to purchase a replacement.