ClarityHow to use this tool
- Enter nominal stored energy, load power, usable fraction.
- Select Calculate to view the result.
- Check the method and assumptions below before using the result.
Input reference and sample values
Use the units and choices shown for each field. Sample values are provided for practice, not as recommendations.
| Input | Format and units | Sample |
|---|---|---|
| Nominal stored energy | Numeric value. Unit: Wh. Must be greater than zero. | 500 |
| Load power | Numeric value. Unit: W. Must be greater than zero. | 50 |
| Usable fraction | Numeric value. Unit: %. Zero or positive. Maximum: 100. | 80 |
Result for these sample inputs
8 hours
Select Try the example in the form to load these values and calculate them again. This replaces the current form inputs. Compare the result with the method and worked explanation below.
The method, explained
Runtime = stored energy × usable fraction/100/load power.
Using nominal stored energy = 500 Wh, load power = 50 W, usable fraction = 80 %, the result is 8 hours. Change these example inputs to match your task; use the method above to check each step.
What to keep in mind
Constant load. Battery age, temperature and protection cutoffs are not modeled. Ideal-component calculation for study and estimation. It does not select safe wiring, protective devices or component ratings for an installation.
Methodology maintained by ClarityKit. How these tools are built and checked.