Sulfation can happen to the lead plates contained in wet cell batteries, commonly known as lead-acid batteries, which are fitted in most vehicles. When sulfation occurs, your battery goes dead. Sulfation is a result of the electrolyte fluid level in the wet cells falling below the top of the lead plates, exposing them. The lead plates are unable to retain electrical energy because the electrons can't flow between the two plates in each cell. Lead plates can't be scrubbed clean, but you can remove sulfation by reconditioning your battery.
Remove the plastic covers from the top of the battery cells. There are either three or six covers, depending on whether your battery is a 6-volt or 12-volt battery respectively. Unscrew the knurled covers using your fingers. If the covers have screwdriver slots, then place a screwdriver into the slots and unscrew them.
Look inside the battery cells. You may need to use a flashlight to see. Look for the two markers on the walls in each battery cell. The mark nearest the top indicates the maximum fluid level, while the lower mark is the minimum. Sulfation occurs after the fluid drops below the minimum level. You can see sulfation on the plates, which looks similar to corrosion on metal, but is yellowish in colour due to the sulphuric acid contained in the cells.
Trickle distilled water carefully into each cell. Fill the cells up to the maximum marker, but not above. You need to allow space for the fluid to expand, which takes place when a battery charges. Don't replace the covers on the battery cells.
Place the clamp on the end of the red positive battery cable from the battery charger onto the positive battery terminal. It's usually labelled "+", or "Pos." Place the clamp on the end of the black battery cable onto the negative battery terminal labelled "-" or "Neg."
Set your battery charger to the lowest voltage charge setting. It may be called "trickle charge." Don't select a fast or boost charge as high charge settings will not properly remove sulfation from the lead plates.
Plug your charger into the power supply. Turn on your charger. Check that you have an illuminated light, which confirms that the battery is charging. If it has a meter, check that it's registering a low charge.
Leave your battery to slow charge for 36 hours. As the battery charges, the distilled water you put into the cells will change into sulphuric acid. The acid will gradually remove the sulfation on the lead plates.
Check the battery after 12 hours. Look into the cells. You should see small bubbles rising, which confirm that the cells are charging. If you put your hand on the wall of the battery, you will find that it's warm. If one or more cells are not producing small bubbles, it's possible the cell is damaged beyond repair; but wait until the end of the charging time.
Look into the cells after 36 hours. Check to see if bubbles are rising to the surface in each cell. There should be a lot of bubbles rising because the battery is fully charged and the sulfation is removed from the lead plates. If there are no bubbles present in any of the cells, it's likely the cell is dead. Replace the battery, as even one dead cell affects the performance of the battery.
Turn off the charger. Remove the two clamps from the battery terminals. Replace the covers on the cells by screwing them in place using your fingers or a screwdriver.
Sulfation can occasionally occur on regular dry cell batteries if the battery leaks. If you see corrosion on any regular battery, don't attempt to remove the sulfation. Dispose of the battery and buy a replacement.
Wear a pair of protective gloves and plastic goggles before attempting this task. The fluid in the cells contains sulphuric acid and will burn you if it comes in contact with your skin, or may blind you if it gets into your eyes.