Rate
Number of amperes for charge or discharge. Also used to express time for either.
Reserve Capacity Rating
The time in minutes that a new, fully charged battery will deliver 25 amperes at 27°C (80°F) and maintain a terminal voltage equal to, or higher than, 1.75 volts per cell. This rating represents the time the battery will continue to operate essential accessories if the alternator or generator of a vehicle fails.
Resistance
The opposition to the free flow of current in a circuit or battery. It is commonly measured in Ohms.
Reversal
Reversal of polarity of cell or battery, due to excessive discharge, or charging in the wrong direction.