Essential to the operation of a motor vehicle, the car battery's first and primary function occurs when the engine is cranked up and started. The term "cranking amps" refers to the power generated by the battery when the ignition key is turned, with a higher number of amps providing more power. Placing the word "cold" in front indicates the number of amps when the weather is cold and there is more strain on the battery.
Amps, the abbreviation for amperes, represents an unit of measurement for the amount of electrical current generated by a battery. All battery-operated devices require a certain amount of energy to work and amps quantifies that amount. For an automobile battery with six cells, each capable of generating 2 volts for a total of a 12 volts, the measurement of cranking amps (CA) represents the number of amps the battery can produce for 30 seconds at 00 degrees Celsius while generating 1.2 volts per cell, or 7.2 volts for the battery. For cold cranking amps (CCA), the standards remain the same with the only difference being the temperature, using -17.8 degrees Celsius. Thus a battery with a CCA of 250 will produce 250 amps for 30 seconds at -17.8 degrees Celsius with 7.2 volts. Automobile manufacturers specify CCA for each model and engine since the primary factor in determining the number of CCAs necessary to start an engine remains the size of the engine. When purchasing a replacement battery, look for one that meets or exceeds the manufacturer's specification for the model and engine.
Every battery must have a CCA specification, based upon testing. According to Cars Direct, the CCAs for Optima batteries are as follows: Red Top (referring to the battery's colour) is 720; Blue and Yellow Tops are both 800. These ratings meet or equal the manufacturer's requirements. In warm climates, meeting the number is generally sufficient, while people who live in cold climates may want the extra protection of a battery that exceeds the requirements.
The Diehard Platinum Batteries from Sears receive good reviews, according to an article in Funskins. An example would be the Platinum P-5 and P-6, both advertised for use in all-weather conditions for luxury automobiles, with a CCA of 740. The Platinum P-2 tops that rating with a CCA of 930.