Automotive Batteries: Specifications
- The most important part about searching for a new battery is finding one with the correct voltage. If a six-volt battery is installed into an automobile that requires a 12-volt battery, the engine will fail to start. If a 12-volt battery is installed in an automobile that requires a six-volt battery, electrical components may be damaged or destroyed.
Some older automobiles (pre-1970) require a six-volt battery. Nearly every automobile manufactured since 1970 requires a 12-volt battery. A good rule-of-thumb to determine the battery voltage is to multiply the number of cell vent caps the battery has by two to determine the voltage. If the battery has three cell vent caps, it is a six-volt battery. If the battery has six vent caps, it is a 12-volt battery. - Automobile manufacturers design each automobile to use a specific battery size. Some automobiles have enough space under the hood to install a battery that is a different size than the original; however, it's never a bad idea to replace the battery with one that is identically sized to the battery that was originally installed.
Automotive batteries are sized by BCI group numbers. For example, if your automobile contains a 12-volt battery that is group size 34, you can be assured that a replacement 12-volt group size 34 battery will fit in the same space that your current battery occupies. - Each automotive battery sold in the United States contains a "cold-cranking amps" rating. This is a measure of how many amperes a battery can provide to your automobile for 30 seconds when the temperature is 0 degrees Fahrenheit. The higher the cold-cranking amps rating, the better the battery will perform in cold weather.
- If your automobile's alternator fails, the battery will be the only source of available electrical power. Each battery sold in the United States is rated in reserve capacity. Reserve capacity measures how long, in minutes, your battery will be able to supply power to the automobile before the battery's voltage falls below the level required to operate your automobile. The higher the rating, the longer the battery can supply power.