Change battery capacity, equipment load, conversion efficiency and reserve level and see estimated runtime update instantly.
Results update instantly as any input changes.
LOAD
Battery capacity alone does not determine operating time. Conversion losses, retained reserve and the actual continuous power draw all reduce the energy available to equipment.
This calculator converts nominal battery capacity into an estimated usable-energy budget and divides that energy by the entered continuous load.
The two sizing cards calculate the nominal battery capacity required to support the current load for eight or twenty-four hours using the same efficiency and reserve assumptions.
This makes the calculator useful in both directions: estimate runtime from an existing battery or estimate battery capacity from a desired operating period.
Worked example: a 1,000 Wh battery powering a 100 W load
With a nominal capacity of 1,000 Wh, an assumed conversion efficiency of 90%, a retained reserve of 20% and a constant 100 W load, the model gives:
1,000 Wh × 0.90 × (1 − 0.20) ÷ 100 W = 7.2 hours, or 7 hours 12 minutes.
This is an illustrative calculation, not a measured product runtime. In this model, the reserve fraction is applied to energy after the assumed conversion efficiency. If a manufacturer’s usable-capacity figure already accounts for losses or a protected reserve, check those definitions before applying another deduction.
The load must be entered in watts. Battery capacity is entered in watt-hours. These are different quantities: watts describe power demand; watt-hours describe an energy amount. The model assumes constant demand and does not independently add inverter standby consumption.
How to cite or reproduce a calculation
Record the four inputs, the displayed runtime and the date you used the tool. A link alone does not preserve the slider settings.
Tecnobosque, Portable Power Runtime Calculator, accessed [date]. Inputs: capacity [Wh], continuous load [W], assumed efficiency [%], reserve [%]. Estimated runtime: [hours]. Model: t = C × η × (1 − R) ÷ P.
Tool URL: https://tecnobosque.com/portable-power-runtime-calculator/. State that the result is a model estimate; it is not certification of equipment compatibility or a manufacturer runtime test.