Reserve Capacity

Reserve capacity is an estimate of how long the vehicle can be driven with no generator output, the head-lamps turned on, and minimum electrical load (most accessories turned off). It is the maximum amount of time (in minutes) it will take for a fully charged battery, being discharged at a constant rate of 25 amperes and a constant temperature of 27°C (80°F), to reach a terminal voltage of 10.5 volts. Other temperatures or current draws, the state of charge, the condition of the battery, etc., will affect how long the battery will actually last when the vehicle is being driven and without generator output.