Depth of Discharge (DoD)

Depth of Discharge (DoD) is the percentage of a battery’s total capacity that has been used. For example, if a 10 kWh battery has discharged 8 kWh, its depth of discharge is 80% (and its state of charge is 20%).

DoD is a critical specification when comparing home batteries because it determines how much of the battery’s rated capacity you can actually use. Most lithium-ion batteries have a recommended maximum DoD of 80–100%. A battery rated at 13.5 kWh with a 100% DoD gives you the full 13.5 kWh of usable energy, while a battery with an 80% DoD only provides 10.8 kWh. Deeper discharges (higher DoD) put more stress on the battery and can reduce its total cycle life. Battery manufacturers balance usable capacity and longevity by setting a recommended DoD in their warranty terms. For instance, a warranty might guarantee 70% capacity retention after 10 years at a maximum 80% DoD. When comparing batteries, always look at usable capacity (which accounts for DoD limits) rather than total capacity.