A car battery helps power your car's engine and provides a charge for all the electrical and electronic accessories. The battery in your car can get old and won't be able to hold a charge or it can be "drained" by accident. Car batteries are drained when someone inadvertently leaves an electrical item, such as a radio, on in the vehicle without the engine running. You need to consider size, cold-cranking amps, battery freshness and reserve capacity as you learn how to buy a car battery.

Steps

1 Learn what battery size you need for your car's make and model.

Consult your car's owner's manual. The manual usually specifies the battery size you should buy.

Ask an auto supply store employee to help you figure out the correct battery size.

2 Pick the correct size and type of battery for your driving needs.

Pick the correct size and type of battery for your driving needs.  Keep driving needs and climate in mind and check your owner's manual for the correct physical size. Consider group size, which refers to the outside dimensions of the battery and the placement of the terminals. If you get a battery that is too small, it won't fit securely in the battery compartment of your car. High temperatures are hard on car batteries. The electrolyte solution in car batteries evaporates more rapidly in hot climates.

A battery with a long life is important if your daily driving habits are primarily short, stop-and-start trips. Short trips don't allow very much time for your battery to recharge.

A battery with a long life is better able to withstand those shorter trips.

3 Look for a battery that has been on the store shelf for less than 6 months.

The date stamp code gives you the battery's freshness information. The first 2 characters are a letter and a digit--A stands for January, B for February, etc.; the digit specifies the year the battery was manufactured--7 stands for 2007, 9 for 2009. The date code is engraved into the cover of the battery. You can find it as you look down at the top of the battery.

4 Ask about "cold cranking amps" (CCA) and "cranking amps" (CA).

These 2 terms are critical, especially if you live in a colder climate.

CCA indicates a battery's ability to start a car in 0 degree F (-17 C). CCA also tells you how much current the battery delivers to your car's starter.

CA tells you how much current your battery delivers to your car when temperatures are 32 degrees F (0 C). This rating is usually higher than the CCA.

5 Inquire about reserve capacity for the batteries that are in stock.

Reserve capacity measures how many minutes the battery may run using its power alone. You need to know the reserve capacity in case your car's alternator should fail.

6 Check the difference between maintenance free (sealed) and low maintenance batteries.

Maintenance free batteries do not need to have water added to them.

Low maintenance batteries are unsealed and have caps on top that allow you to add water--an important consideration if you live in a hot climate.