Charge and discharge depth and efficiency of energy storage batteries

What is depth of discharge (DOD) of a battery?

The Depth of Discharge (DOD) of a battery determines the fraction of power that can be withdrawn from the battery. For example, if the DOD of a battery is given by the manufacturer as 25%, then only 25% of the battery capacity can be used by the load.

What is depth of discharge (DOD) in energy storage?

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.

What happens when a battery is discharged to an extended depth?

When a battery is discharged to an extended depth, more energy is released during a single discharge cycle. An increase or decrease in discharge depth, for example, from 2.7 V to 2.5 V, generally has a limited effect on the energy efficiency, as shown in Fig. 9 (c).

How can a battery be discharged at different depths?

Discharging batteries at different depths can be achieved by using different cutoff voltages. When a battery is discharged to an extended depth, more energy is released during a single discharge cycle.

How efficient are battery energy storage systems?

As the integration of renewable energy sources into the grid intensifies, the efficiency of Battery Energy Storage Systems (BESSs), particularly the energy efficiency of the ubiquitous lithium-ion batteries they employ, is becoming a pivotal factor for energy storage management.

How does deep discharge affect battery life?

Depth of Discharge (DOD) A battery’s lifetime is highly dependent on the DOD. The DOD indicates the percentage of the battery that has been discharged relative to the battery’s overall capacity. Deep discharge reduces the battery’s cycle life, as shown in Fig. 1. Also, overcharging can cause unstable conditions.