Calculator
Battery Runtime Calculator
Estimate DC battery runtime from voltage, amp-hour capacity, load watts, and efficiency.
Calculator Inputs
Battery voltage must be a valid number.
Battery capacity must be a valid number.
Load must be a valid number.
Legend
Battery runtime legend
Voltage multiplied by amp-hours estimates stored energy. Efficiency accounts for conversion and system losses before dividing by load.
Input meaning
- Battery voltage: nominal battery voltage.
- Battery capacity: rated amp-hour capacity.
- Load: connected equipment load in watts.
- Efficiency: estimated conversion efficiency.
Result interpretation
- Usable energy is an estimate, not a guaranteed clinical runtime.
- Estimated runtime should be verified for critical biomedical devices.
Assumptions
- Battery is healthy, charged, and operated within temperature limits.
- The equipment load stays constant.
- Battery chemistry and discharge curve are not modeled in detail.
Biomedical use
- Useful for portable monitors, infusion devices, transport equipment, small UPS checks, and backup-battery replacement planning.
How to identify the required values
Use these examples to choose values from gauges, labels, manuals, datasheets, or service reports.
| Field | Example value | Tip |
|---|---|---|
| Battery voltage | 12 V battery pack. | For series packs, use total pack voltage. |
| Battery capacity | 7 Ah printed on sealed lead-acid battery. | Use rated Ah only for healthy batteries; derate old batteries. |
| Load | Infusion pump 20 W or monitor 80 W. | Use measured equipment load for better estimates. |
| Efficiency | 90% for a simple DC system; 80-85% for inverter-backed loads. | Lower the efficiency if cables/inverter losses are uncertain. |
Input Checklist
Confirm these values before relying on the output for procurement, PM, or service planning.
- Battery voltage
- Battery capacity
- Load watts
- Efficiency
Safety And Engineering Notes
Use calculator outputs as planning estimates and verify critical systems with calibrated measurement or qualified engineering review.
- Real runtime depends on battery age, chemistry, temperature, and discharge curve.
- Verify critical equipment runtime with actual load testing.