A practical planning tool
Battery Runtime
Calculator.
Enter battery capacity and a constant appliance load. Adjust the usable-energy assumption to see how it changes your runtime estimate.
Battery Runtime Calculator
Adjust capacity and load to explore a constant-power estimate. Appliance presets use example wattages.
Estimated runtime
for your appliance load
Formula & assumptions
Rated Wh × chosen usable-energy fraction ÷ watts. The default 85% is an assumption, not a measured efficiency. Actual runtime varies with load, temperature, battery condition and standby draw. This tool does not check startup surge, solar recharge or device compatibility.
Illustrative appliance loads
Three numbers.
One useful starting point.
The calculation
Rated capacity (Wh) × usable-energy fraction ÷ appliance power (W) = estimated hours.
What changes the result
Actual runtime varies with load, battery condition, temperature, conversion losses and standby draw. Use your device’s measured average consumption when available.
Does this choose a compatible power station?
No. Check continuous output, startup surge and any device-specific requirements separately. The calculator does not size an inverter, build a daily appliance schedule or model solar charging. Medical equipment needs an appropriate backup plan confirmed with its provider.
Which usable-energy fraction should you use?
Start with the adjustable 85% planning assumption, then use model-specific usable-energy data if available. The example appliance wattages are illustrative constant loads, so enter your device’s average consumption for a more relevant estimate.
Put the estimate in context.
Use the estimate to narrow a capacity range. Then compare output limits, weight, charging options and the exact package.
Compare portable power stations