What is the Difference between MCA and CCA on Batteries?
 

I replaced my old Interstate deep cycle marine battery it was shot. On the battery decal it had 675 CCA (Cold Cranking Amps) and 845 MCA (Marine Cranking Amps).

The new battery I bought from Auto Zone which is a dual purpose starting and deep cycle battery only says 800 MCA (Marine Cranking Amps). My question is what is the difference between Marine Cranking Amps (MCA) and Cold Cranking Amps (CCA)?

When I asked the punk at Auto Zone this his reply was: DUHHHH? I don't know dude.

MCA is rated at 32 degrees F
CCA is rated at 0 degrees F

A 45 A difference will not make that much difference.

insptech is correct. here is how to convert the cca to mca, and visa versa....

COLD CRANKING AMPS (CCA)
The CCA rating represents in amps the current flow the battery can deliver for 30 seconds at 0o F. without dropping below 1.2 volts per cell (total of 7.2 volts for a 12-volt battery). The higher the number, the more amps it can deliver to crank an engine.

MARINE CRANKING AMPS (MCA)
Batteries designed for marine use may be rated at MCA instead of CCA. The MCA rating method measures battery output at 32o F., not 0o F. A battery's MCA rating will be one-third higher than its CCA rating would be.
To compare two batteries when one has an MCA rating and the other has a CCA rating. multiply the CCA rating by 1.3 for the equivalent MCA rating. Or, multiply the MCA rating by 0.77 for the equivalent CCA rating. Example:

500 CCA x 1.3 = 650 MCA
or
650 MCA x 0.77 = 500 CCA

Thanks for the info. Findme - if you do that formula above on my original battery it does not come out.

675 CCA x 1.3 = 877.5 MCA

The old battery says 675 CCA and 845 MCA.

I think your multiplier should be 1.2519, then it would come out. I guess you just rounded up.

Find me stays lost !!! he did not even copy it out of the book right

Intelligent post there CESSNA... Aren't you supposed to be at "Airplanes only"? lol Glad to see we have a new member who likes to flap his lipps instead of try to help.... and by the way.... I have forgotten more than you will ever know, ya wanna get technical and make a fool out of yourself (again)?

Thanks for the help Findme, knowledge is a powerful thing, its posts like yours that make this site great. Thanks again for the help. Eric

If you have a lust for even more minutiae about batteries and amps and how long they last and the optimal way to keep 'em charged and long lived, Interstate has a really nice little booklet they hand out for free. It doesn't especially push their product vs others products. It's about a ten minute read and I found it very educational.