A car battery that fails can be a serious thing, because it usually means a lot of expense, and a lot of inconvenience. There's very little that you can do about the inconvenience if your car breaks down on the road somewhere and refuses to start, but you can do a lot about the expense.

Instead of buying a new battery, you can simply restore and recondition your old battery.

The procedure is really rather simple and one that can be done at home or wherever you have a little space to work in.
You will need a little protective equipment - basically, a pair of rubber gloves to protect your hands, and goggles or a mask to protect your eyes and face.

The first thing you need to do is to make sure that the car is properly cooled down, and the battery likewise. At this point, you need to open up the hood and remove the battery from its clamps. You will also need to, obviously, disconnect the cables of the battery.

Now, the negative comes first, and after that, you will that detach the positive cable.

This order cannot be reversed. You will remove the negative first.

If you fail to do so, you can damage the electronics in your car. When you detach the battery from your car, make sure that you're wearing insulated footwear, and that no part of your body, including the metal wrench, touches any other portion of the car other than the battery.

Now, pick up the battery and move it to a place where you can work.
This should preferably be on a concrete floor or at least a floor impervious to battery acid. Under no circumstances should you work on the bare ground, as the corrosive acid seeping into the ground could cause serious damage to the environment. Now, all you need to do is open up the caps of the battery and empty out the liquid you find inside into a handy container.

Please note that the container you empty the liquid into must not be made of metal, as the liquid is sulfuric acid and will react with many metals.

The next step is to take around five liters of water and to put about two hundred and fifty grams of Epsom salt into it. You'll need to mix the Epsom salt into the water completely, and this is much easier if the water is hot. In any case, hot water will serve the reconditioning process much better.

You will take this hot liquid and pour it into the cells of the battery, using a funnel to ensure that not much of it spills. Then close the cells of the battery, and let the battery stand for up to six hours.

After this, charge the battery normally until it reaches a full charge - then discharge it under a load, and charge it again to complete the conditioning process. After this, the battery should return to normal and work properly.

The Epsom salt breaks down sulfation inside the battery, which is an insulation layer that forms on the lead plates within the battery. Once this insulation layer is broken down, the battery functions once again, and will regain a great deal of its capacity.

After this, all you need to do is put your battery back into the car and reattach the terminals.