How to Recondition Lead-Acid Batteries

by James Stevens

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Lead-acid batteries are wet cell batteries. Each cell contains two slightly different lead plates, and the plates sit in electrolyte fluid, which contains sulfuric acid. If the electrolyte level gets too low, the lead plates are exposed and sulfation -- the deposit of a hard lead-sulfate compound on the lead electrodes of the battery -- occurs. This restricts the flow of electrons from one plate to the other and the battery cell is unable to retain a charge. If you find your battery doesn't have the power to start your vehicle or isn't charging correctly, try reconditioning the lead-acid battery before getting a replacement.

Step 1

Wear a pair of lightweight rubber gloves to protect your hands before attempting to recondition your battery. The fluid in the lead-acid battery cells burns if it gets on your skin.

Step 2

Remove the caps on the top of the lead-acid battery. If the caps have slots in them, use a fairly large flat-head screwdriver to unscrew them, and then lift off the caps, using your fingers. Many cell caps simply screw in place, so you can remove them in this manner.

Step 3

Check the fluid level in the cells. If the fluid level is below the minimum marker on the wall of the cell, it means the lead plates may be exposed, and sulfation may have occurred.

Step 4

Use distilled water, not tap water, and top up all the cells to the maximum marker. Don't go past the maximum marker, because the fluid expands while the lead-acid battery charges.

Step 5

Leave the caps off the battery, and attach the two clamps on the ends of the red and black battery cables of the battery charger to the "+" and "-" terminal poles respectively on your lead-acid battery. Squeeze the clamp handles to open the jaws of the clamps, and then place the clamps over the terminal poles and release the pressure so the jaws of the clamps close securely.

Step 6

Plug your charger into the power supply. Select a slow charge; a fast charge won't satisfactorily recondition your battery cells.

Step 7

Turn on your battery charger. To make sure it's charging, check to see if the charging light is on, or check the charge display panel, if there is one.

Step 8

Allow your battery to charge slowly for at least 24 hours; 36 hours are better, if you have the time. During this time the cell will start to recondition and turn the distilled water into sulfuric acid. The acid will remove the sulfation from the lead plates, and the electrons will start to flow from one plate to the other and take a charge.

Step 9

Turn off your battery charger after 24 hours to 36 hours. Remove the plug from the power supply, and remove the clamps from the terminal poles on the lead-acid battery.