Car Batteries 101: What is Reserve Capacity?
Reserve capacity rates how long a car battery can hold its minimum amount of power before dropping below 10.5 volts. The RC rating, also known as reserve capacity minutes, is listed on a battery in total minutes. A battery should be able to deliver at least 25 amperes consistently before the voltage drops, so a higher RC rating means a car battery will be able to sustain itself for a longer period of time.
Facts about Battery RC Rating