The primary difference between MCA (Marine Cranking Amps) and CCA (Cold Cranking Amps) lies in the temperature at which the battery's cranking power is tested.
MCA vs. CCA: The Key Distinction
Both MCA and CCA ratings indicate a battery's ability to deliver a high burst of current needed to start an engine. They measure the maximum current a battery can supply for 30 seconds while maintaining a voltage of at least 7.2 volts (for a 12V battery). However, the CCA rating is based on amps delivered at 0℉ and the MCA rating is done at 32℉.
This temperature difference is significant because cold temperatures reduce a battery's ability to produce current, and also make an engine harder to crank.
- CCA (Cold Cranking Amps): Tested at a much colder temperature (0°F or -18°C). This rating is crucial for vehicles operating in freezing climates where starting an engine is more challenging.
- MCA (Marine Cranking Amps): Tested at a warmer temperature (32°F or 0°C). This rating is commonly used for marine batteries, as boats are often used in less extreme cold than cars or trucks operated in winter climates.
Why Does the Testing Temperature Matter?
A battery's chemical reactions slow down in the cold. This means a battery will have a lower cranking amp rating at 0°F than it will at 32°F. Therefore, a battery with a given MCA rating will have a lower CCA rating.
For example, a battery rated at 800 MCA might only be rated at 650 CCA.
Summary Table
To quickly illustrate the difference:
| Rating | Testing Temperature | Primary Application |
|---|---|---|
| CCA | 0°F (-18°C) | Automotive batteries in cold climates |
| MCA | 32°F (0°C) | Marine batteries, less extreme cold |
Choosing the Right Battery
Understanding the difference is vital when selecting a battery:
- For vehicles used in freezing winter conditions: Prioritize the CCA rating. Ensure it meets or exceeds the vehicle manufacturer's recommendation.
- For boats or vehicles in milder climates: The MCA rating is relevant, but it's still helpful to know the CCA rating if you anticipate using the battery in colder conditions. Some battery manufacturers provide both ratings.
In essence, MCA and CCA measure the same capability (delivering starting power), but the temperature at which the test is conducted is the key differentiator, reflecting the demands placed on the battery in different environments.
