Charge and discharge rates affect the rated battery capacity. If the battery is discharged quickly using a high current, then the actual battery capacity will be lower than the rated battery capacity.
Battery capacity is measured either in watt-hours (Wh), kilowatt-hours (kWh) or, most commonly, in ampere-hours (Ah) which indicates the number of hours for which a battery can provide a current equal to the discharge rate when the battery is operating at its nominal voltage. Charge and discharge rates affect the rated battery capacity.
Maximum 30-sec Discharge Pulse Current –The maximum current at which the battery can be discharged for pulses of up to 30 seconds. This limit is usually defined by the battery manufacturer in order to prevent excessive discharge rates that would damage the battery or reduce its capacity.
Maximum Continuous Discharge Current – The maximum current at which the battery can be discharged continuously. This limit is usually defined by the battery manufacturer in order to prevent excessive discharge rates that would damage the battery or reduce its capacity.
In this case, the discharge rate is given by the battery capacity (in Ah) divided by the number of hours it takes to charge/discharge the battery. For example, a battery capacity of 500 Ah that is theoretically discharged to its cut-off voltage in 20 hours will have a discharge rate of 500 Ah/20 h = 25 A.
It is the charge or discharge current in Amps divided by the cell capacity in Ampere-hours. A 1C rate means that the discharge current will discharge the entire battery in 1 hour. If we plot charge / discharge rates in Amps versus battery capacity in Ampere-hours we get straight lines for a given C-rate.