Depth of discharge (DOD) is the percentage of discharge capacity of a battery to the nominal capacity of the battery.
The discharge depth of a shallow cycle battery should not exceed 25%. A deep cycle battery can release 80% of its capacity.
The state of charge (SOC) of a battery is the ratio of the amount of charge available at a given moment to the amount of charge available at full charge. SOC is expressed as a percentage, with 100% indicating full charge status and 0 indicating empty charge status.
In the case of no load, all linear relationships of the state of battery charge capacity measured in ampere-hours or watt-hours. For example, if the capacity of 302Ah is regarded as 100% SOC, when the capacity is 0Ah, the SOC is 0%