MCA stands for “marine cranking amps.” It tells you how many amps your engine will receive at 32 degrees Fahrenheit. A related rating is CCA, which stands for “cold cranking amps.” This rating tells you how many amps your engine will receive at 0 degrees Fahrenheit. Which rating you should pay attention to depends on the conditions in which you expect to need to start your engine. What is most important is simply not to mix up the two ratings.