Depth of discharge
Depth of Discharge (DoD) is an alternate method to indicate a battery's state of charge (SoC). The DoD is the complement of SoC: as one increases, the other decreases. While the SoC units are percent points (0% = empty; 100% = full), DoD can use Ah units (e.g.: 0 = full, 50 Ah = empty) or percent points (100% = empty; 0% = full). As a battery may actually have higher capacity than its nominal rating, it is possible for the DoD value to exceed the full value (e.g.: 55 Ah or 110%).
At least in some battery technologies such as lead-acid AGM batteries there is a correlation between the Depth of discharge and the Cycle life of the battery.[1] Depth of Discharge (DOD) is defined as: Capacity in Ampere Hours (Ah) that is discharged from a fully charged battery, divided by battery nominal capacity (C20). DOD is normally presented in percent (%). Example: if a 100Ah battery is discharged for 20 minutes at 50A, the Depth of Discharge is: 50*(20/60)/100= 16.7%