The charging/discharging rates affect the rated battery capacity. If the battery is being discharged very quickly (i.e., the discharge current is high), then the amount of energy that can be extracted from the battery is reduced and the battery capacity is lower.
The charge and discharge rates of a battery are determined by C rates. The capacity of a battery is usually specified as 1C, which means that a fully charged battery with a capacity of 1Ah will deliver 1A for one hour. The same battery discharged at 0.5C should deliver 0.5A for two hours, and at 2C it will deliver 2A for 30 minutes.
The charging/discharge rate may be specified directly by giving the current - for example, a battery may be charged/discharged at 10 A. However, it is more common to specify the charging/discharging rate by determining the amount of time it takes to fully discharge the battery.
4.10. Rated battery discharge efficiency ηD,n Typically rated battery discharge efficiency ηD,n is determined at beginning of life (BOL) and for certain conditions specified by battery manufacturer. So rated battery discharge efficiency can be determined during rated capacity verification test and may be used as battery acceptance criterion.
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.
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 30-sec Discharge Pulse Current This is the maximum current at which the battery can be discharged for pulses of up to 30 seconds.
For example, if 10 kWh is pumped into the battery while charging, and you can effectively retrieve only 8 kWh while discharging, then the round trip efficiency of the storage system is 80%. Let''s discuss another important battery parameter, …