The area is the energy, E = 0.5 * Q * U, Q = U * C Total Energy stored in the capacitor, = QV/2 = 0.5 CV^2 where, Q = amount of charge stored when the whole battery voltage appears across the capacitor. V= voltage on the capacitor proportional to the charge. Then, energy stored in the battery = QV
As the discharge rate ( Load) increases the battery capacity decereases. This is to say if you dischage in low current the battery will give you more capacity or longer discharge . For charging calculate the Ah discharged plus 20% of the Ah discharged if its a gel battery. The result is the total Ah you will feed in to fully recharge.
Capacity is calculated by multiplying the discharge current (in Amps) by the discharge time (in hours) and decreases with increasing C-rate.
An equation is given for calculation of Charge/Discharge efficiency rate during charging mode which is: Eta= 1-exp (20,73* (SOC-1) / (I/I10)+0,55) Where I10 is the current at C10 I is the battery current
Depth of Discharge (DOD) is another essential parameter in energy storage. It represents the percentage of a battery’s total capacity that has been used in a given cycle. For instance, if you discharge a battery from 80% SOC to 70%, the DOD for that cycle is 10%. The higher the DOD, the more energy has been extracted from the battery in that cycle.
C-rate is an important information or data for any battery, if a rechargeable battery can be discharged at that C rating, a 100Ah battery will provide about 100A, then the battery has a discharge rate of 1C. If the battery can only provide a maximum discharge current of about 50A, then the discharge rate of the battery is 50A/100Ah=0.5C.