- Cold Cranking Amps ("CCA")
For motor start battery applications such as diesel motors for fire pumps, Cold Cranking Amps ("CCA") is a measure in cold climates of the discharge load (current) measured in amperes, that a new fully charged battery at 0ºF or -17.8ºC can deliver for 30 seconds while maintaining a terminal voltage (the voltage between the negative and positive terminals of a battery) greater than or equal to 7.2 volts, or not less than an average of 1.2v per cell for a 6 cell, 12v battery.
It is generally considered that the higher the CCA rating of a battery, the greater capacity of the battery for starting a motor.
A battery may also be rated in Marine Cranking Amps ("MCA") also known as or Cranking Amps ("CA"), which is a similar rating system where the discharge load (current) measured in amperes for a new, fully charged battery at 0°C or 32ºF can continuously deliver for 30 seconds and maintain a terminal voltage greater than or equal to 7.2 volts, or not less than an average of 1.2v per cell for a 6 cell, 12v battery.
Calculating battery capacity using Marine Cranking Amps or Cranking Amps is based on a higher temperature, similar to those found in Australia, as compared to Europe and North America in winter which leads to a higher rating (up to 20%) than the more popular Cold Cranking Amps rating system.
Another measure of battery capacity for standby batteries is Ampere Hour (Ah) also known as Amp Hour, or for smaller batteries Milliampere Hour (mAh) and is the measure of the discharge of stored electrical energy over time.
One Amp Hour (Ah) is the amount of stored energy (battery capacity) that will allow one ampere of current to flow for one hour.