As Daddle says.
See also ➥ Deep-Cycle RV Battery Ratings and Specifications: CCA, MCA, RC, Ah,
Banks require high Amp/Hour capacities.
The amp-hour rate (or 20 hour rate) is measured at a current
that drains the battery
capacity in 20 hours to a voltage point of 10.5 volts. This test is conducted at 80°F.
Starting Batteries require high Cranking Amperes.
Battery capacity and voltage are reduced as the temperature declines. To start a car on a freezing winter
morning, a powerful battery is needed. CCA or CCP is the maximum discharge current
in amps that a new, fully charged 12 volt battery at 0°F can deliver for 30 seconds and maintain a voltage of 7.2 volts. MCA uses the same method except the temperature is 32°F. The higher the CCA or MCA rating the easier it will be to start your engine
in cold weather
Batteries are also rated in reserve capacity or peak capacity. Reserve capacity is a test in which a discharge load of 25 amps is placed on a battery at 80°F, and the time is measured until the battery voltage reaches an end point of 10.5 volts. The higher the reserve capacity the greater the amp-hours a battery holds.