What is the marine cranking rating (MCA)?
The marine cranking ampere (MCA) rating refers to the number of amperes a battery can support for 30 seconds at a temperature of 32°F until the battery voltage drops to 1.20 volts per cell, or 7.20 volts for a 12V battery. Thus, a 12V battery that carries a MCA rating of 600 CCA tells us that the battery will provide 600 amperes for 30 seconds at 32°F before the voltage falls to 7.20V. Note that the MCA is sometimes referred to as the cranking amperes or CA.