If your car is to be left unused or idle for a long time, you should disconnect the battery. This will slow down its discharge rate and prevent the battery from going flat fast. If A BATTERY is stored for a long time, it will discharge through internal leakage. A battery charger will keep the battery in peak condition, especially during the winter. It also has a further use: a fully charged battery will produce only about two-thirds its power when cold, but half an hour on a trickle charge will warm it up, so that it can punch out full starting power. A distilled-water filler avoids overfilling and subsequent corrosion of the terminals by cutting off the flow as soon as the correct level is reached.

If you are not using the vehicle for a long period of a month or so then remove the terminals from the battery. This prevents the discharge and prolongs the life of the battery. With a little knowledge and hands on car battery maintenance, it would be easy to identify early signs of low or failing car battery. Here are the most common but significant signals of low or failing battery:

• Dim headlights when the car is idle
• Starter turns slow
• Problem in the ignition
• Loose or cracked fan belt
• Dim dash lights
• Ineffective cooling in the car cabin
• Short circuit in the electric wirings
• Improper functioning of various electrical devices in the car.

After identifying the symptoms of failing battery, it is also essential to know the actual causes of battery malfunction. Knowledge of the causes of car battery failure assists to take good care of it ensuring a prolonged and problem free life.
Here are some of the culprits of battery weakening or failure:

• Rash driving habits are common culprits of battery malfunction
• Excessive use of electrical power for various car electronics like car air-conditioner, music system, or car cabin lights
• Leaving the cabin lights open through the night drain much of battery power
• Using car air-conditioner when the car engine is idle
• Sometimes, it may also because of factory defects.

Like most other parts of the modern car, your batteries too are practically "maintenance free". Most car batteries today no longer require frequent servicing in the form of topping-up of the electrolyte level, although checking should be done at regular intervals as specified in your owner's manual. However wherever required, "topping-up" should be done meticulously once in 15 days. Only distilled water should be used for topping-up.

Improper functioning of the battery can cause starting problems and over-charging (which is indicated by inconsistent functioning of the horn and light). Following checks should be made:

• Battery terminals are clean and that there is no sulphur formation.
  Disconnect the cables from the battery and clean them with a wire brush that has been doused in a home made mixture [the mixture combines one tablespoon of baking soda with one cup of water]. Use this same mixture to clean off the top of the battery; use a small and clean paint brush to apply the solution where needed.
• The battery is always be tightly bound to the battery-tray, to prevent spillage and damage.
• Battery cables are properly connected.
• Generator drive belt is sound and correctly adjusted. The driver belt is very critical to the electrical system of your car because without it the generator will not charge effectively resulting in your car running out of electricity. In some systems it may also drive the cooling system (water-pump) and the engine-cooling fan as well. Thus a belt that is malfunctioning could also cause something as serious as an engine seizure.
• A small dab of petroleum jelly to lubricate each post will help keep your cables clean and free of corrosion longer. In addition, the jelly will make it easier for you to slip the cables back onto the battery.
• Make wise use of all the electrical devices in the car. Switch off the car air conditioner and music system when not required. Unnecessarily leaving the car cabin lights on would also drain out battery life. All the electrical devices suck out power from the battery that cannot be recharged or regenerated.

When servicing a battery, work in an open, ventilated area, and always wear safety glasses. Battery acid is very corrosive: take care not to get any on your skin or clothes.

Before you start, always check the type of grounding system the vehicle has. If you remove the positive connector first in a negative ground system, you risk the chance of creating a spark. That could happen if the metal tool you're using to remove the positive terminal connector comes in contact with any piece of metal on the car. If you are working near the battery when this occurs, it might create an ignition source that could cause the battery to explode. It's extremely important to remove the ground source first.