Capacity used is the numerator; nameplate capacity is the denominator. This guide shows how to calculate battery DoD % from capacity used—watt-hours consumed versus total pack Wh for an accurate discharge percentage.
Benefits
- DoD % = (capacity used ÷ total capacity) × 100 in Wh.
- Same ratio in Ah when voltage is constant across the cycle.
- Turns load logs and shunt readings into warranty-friendly DoD %.
How it works
- Sum energy used in Wh (battery monitor, inverter tally, or W × h).
- Enter total bank Wh at full charge (Ah × V or datasheet kWh).
- Multiply the ratio by 100—read DoD % for the cycle or day.
FAQ
How do I calculate battery DoD % from capacity used?
DoD % = (used ÷ total) × 100. Example: 840 Wh used from a 2,400 Wh bank → (840 ÷ 2,400) × 100 = 35% DoD. If you track Ah at steady voltage: used Ah ÷ total Ah gives the same percentage.
Can I use Ah instead of Wh for capacity used?
Yes when bus voltage is nearly constant during the discharge—used Ah ÷ total Ah equals DoD %. If voltage sags significantly, prefer Wh from a monitor or Ah × average V for better accuracy.
What if capacity used exceeds nameplate total?
Used cannot exceed total in the calculator—check whether total Wh was derated for age or whether the shunt includes inverter return energy. Regen or charging during the window reduces net used Wh.
Technical specifications
- DoD % = (capacity_used_Wh ÷ total_Wh) × 100.
- Ah method: used_Ah ÷ total_Ah (constant V).
- Remaining SoC % ≈ 100 − DoD %.
- Related: battery-depth-of-discharge-calculator, battery-energy.