Rating of a battery is determined by the current it can produce and the time for which it can sustain this current. Batteries are rated in many ways the most important of which are:

• Ampere Hour capacity: It represents the lasting power of a battery on small load. It represents the rate of current a battery can deliver continuously for 20 hours after which the cell voltage should not drop below 1.75V at 80 °F.
• Twenty minute rate: It represents the rate of current a battery can deliver continuously for 20 minutes the cell voltage not dropping below 1.5V at 80 °F.
• Reserve capacity: RC is a battery's ability to sustain a minimum stated electrical load; it is defined as the time (in minutes) that a lead-acid battery at 80 °F will continuously deliver 25 amperes before its voltage drops below 10.5 volts.
• Cold cranking amps: CCA is a measure of a battery's ability to start a car in cold weather, when thickened engine oil and slowed chemical reactions make starting hardest. CCAs denote how much current the battery can deliver to the starter at 0° F. It represents the current in amperes which the battery can supply continuously for 30 sec or 1minute without cell voltage dropping below 1.4V.