How to Renew a Car Battery

by William Adkins

Modern car batteries are reliable and long-lasting. When they cease to work properly, it is usually due to sulfation. Sulfation occurs when the lead electrodes in the battery become coated with sulfur from the sulfuric acid electrolyte. The primary cause of sulfation is repeated deep discharges (running the battery down). There are several methods for reversing sulfation, provided the sulfur hasn't corroded the lead plates too badly. The simplest and least expensive requires only a common household chemical and a good quality "smart" charger designed for use with car batteries.

Step 1

Use a crescent wrench to loosen the battery cables and remove the battery from the car. Work in a well ventilated area and always wear gloves and safety glasses when working with lead acid batteries. Keep open flames away from the work area.

Step 2

Remove the cell caps located on top of the battery. If it's a sealed battery, locate the entry points (called shadow caps) marked on top of the battery and use a drill to punch through them. Drain the battery fluid into anon-metallic container.

Step 3

Mix a solution of 15 percent to 20 percent by weight of magnesium sulfate (better known as Epsom salts) and water--about 7 oz. of Epsom salts to 1 qt. of water). Use distilled water since tap water sometimes contains chemicals harmful to batteries. When the Epsom salts are completely dissolved, fill each cell of the battery with the solution.

Step 4

Charge the battery using a 3-phase "smart" charger set to 12 volts. These chargers are designed to provide optimum charging with an initial "bulk" charge followed by a slower absorption charge and finally a trickle or "float" charge. Make sure the charger is turned off and follow manufacturer's instructions for connecting the battery to the charger. Turn the charger on and allow the battery to charge overnight.

Step 5

Turn the charger off and disconnect the battery. Replace the cell caps. Use plastic plugs to fill the shadow plug holes in a sealed battery. Finally, reinstall the battery in the car. Make sure the battery cables are securely fastened.

Step 6

Complete the renewal process by removing the battery and bring it to full charge using the battery charger once a week for two or three weeks.

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