It is relatively easy to replace a car battery as part of routine maintenance. Although there is a dizzying array of batteries available on the market, Consumer Reports notes that three companies produce the majority of maintenance-free batteries used in the United States today – Johnson Controls Industries, Exide and East Penn. Batteries are manufactured by different companies and marketed by different companies under different names. The brand name doesn’t matter. There is a relationship between age, cold cranking amps, reserve capacity, and group size.
- Batteries usually have a manufacture date on them, and they should be sold within six months of that date. Make sure the date is accurate before you buy. The date is usually coded. Codes usually begin with the letter indicating the month: A for January, B for February, and so on. As in 0 for 2000 or 1 for 2001, the number indicates the year.
- The battery group size determines the outside dimensions and the location of the battery terminals. Ensure that the group size of the battery you’re buying matches the one you’re replacing – otherwise you can wind up with a battery that’s not compatible with your car. Fortunately, most battery sellers group them by make, model, and year of the car.
- CCA: This is a measurement of a battery’s capacity to start a car at 0 degrees Fahrenheit (-17 degrees Celsius), when the engine oil is thick and the battery’s chemical potential is low. Generally, the higher the CCA, the better it will start cold. Batteries usually list this on the sticker, though some list only cranking amps. CA is measured at 32 degrees Fahrenheit (0 degrees Celsius) and is typically a higher number. However, it does not provide an accurate assessment of how well the car will start in cold weather.
- Reserve capacity: This is the most difficult number to find, but it is the most useful. If your car’s alternator suddenly fails, it tells you how long it can run on battery power alone. You can usually find it in the battery literature at the store or online, or sometimes on the battery itself.
You should be able to withstand the worst a bad battery can do to you, and find a reliable new one when you need it.