PowerRuntime

PowerRuntime is a fully offline calculator for battery runtime. Estimate how long devices will run on batteries, power banks, UPS units, and portable power stations — with no internet, no account, and no ads. • Power sources: Wh or Ah + V, continuous and peak power, efficiency, reserve, and idle draw • Devices: average, peak, and cyclic loads with quantity • Multi-device scenarios with fast recalculation • Optimistic, expected, and conservative runtime ranges • Continuous and peak power compatibility checks • Compare all sources under the same load • Saved calculation snapshots and global search • Built-in and custom efficiency presets • JSON export and import via the system file picker • Light/dark theme and Dynamic Color All data stays on your device. The app has no INTERNET permission and works completely offline.