Depth of Discharge (DoD) explained
Depth of Discharge (DoD) describes how much of a battery's total energy capacity is used before it's recharged. A 10 kWh battery discharged to 80% DoD delivers 8 kWh of usable energy in each cycle.
Why DoD matters:
- Higher DoD = more usable energy per cycle, but potentially faster degradation
- Battery manufacturers specify their cycle life warranties at a particular DoD — e.g. "6,000 cycles at 80% DoD"
- Operating at lower DoD (e.g. only ever discharging to 50%) extends battery life significantly, but reduces the usable capacity you've paid for
DoD by technology:
- LFP lithium-ion (e.g. Tesla, BYD): typically rated to 90–95% DoD, with most manufacturers using 80% DoD as the warranty benchmark
- NMC lithium-ion: similar but some manufacturers limit to 80% DoD
- Lead-acid: should not exceed 50% DoD without significantly shortening lifespan
In practice, most home battery management systems (BMS) automatically limit discharge to the manufacturer's recommended DoD. The battery may show "0%" on your app but actually retains a protected reserve. Understanding this helps you interpret battery monitoring data accurately.