Formula
Daily energy = active power × active hours + sleep power in watts × sleep hours. Runtime days = nominal energy × usable rate ÷ daily energy.
What the result means
The runtime is a steady-duty-cycle estimate. Shortening active time can materially extend life because active power is often far greater than sleep power.
Add self-discharge, temperature effects, transmission retries, and end-of-life voltage constraints through a conservative usable-capacity input or a more detailed engineering model.