Regardless of how old, new, cheap or expensive your automobile is, without a properly functioning car battery it becomes pointless. Car batteries can die, or become flat, for a variety of reasons. While some of these reasons are hard to prevent, others can be prevented with proper maintenance and care.
The most obvious sign of a flat battery is when you turn the ignition key and the car doesn't start. If the car battery is flat, you will not hear any sounds when the ignition key is turned. If the dashboard lights illuminate briefly and then go out, that is another sign of a flat car battery. Sometimes the battery is not entirely flat, but is about to die. If this is the case, the car engine will struggle to start. The dashboard lights will dim while the key is turning the ignition. These lights will not get brighter, nor will they go out completely.
Leaving on any kind of light, such as an interior light or a headlight, can cause the battery to become flat. Automobiles that are parked for a long period of time -- several weeks -- can also suffer from a flat battery. Often, the battery has simply worn out due to excessive use and needs to be replaced. Always make sure all lights associated with your vehicle have been turned off before you walk away. A bad alternator or starter can also cause the battery to become flat.
Jumper cables can be used to bring new life into a flat battery. To start, place two cars next to each other so that the cables can reach each battery. Obviously, one of the two batteries should be fully functional. Make sure both cars are completely off to begin with. The jumper cables will have two leads on each end: one red and one black. The car battery will have both positive and negative terminals, which will be clearly marked. Starting with the dead battery, connect the red lead to both positive terminals. Then connect the black lead to the functioning battery's negative terminal and the other black lead to a bare metal part on the dead car's engine. Start the car with the good battery and let it run for a few minutes so that it can charge the dead one. Turn off the car and remove the cables. The dead battery should now be charged and ready to go.
Before purchasing a new car battery, make sure the old battery is actually dead. In some cases the battery might be fine but the terminals, or the knobs on the battery that connect wires to the alternator, may be corroded due to sulfate buildup. You can use a hammer to try and break this corrosion away or a mixture of baking soda and water. Rub this mixture on the corroded terminals with a toothbrush to see if the corrosion will scrub off. If that battery is still not connecting, and jumper cables did not help, simply go and buy a new battery. Remember to recycle the dead battery. You may do this at a recycling center, service garage or auto supply store.
