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: enter the measured, quoted, or hospital-approved value in V.
- Battery capacity: enter the measured, quoted, or hospital-approved value in Ah.
- Load: enter the measured, quoted, or hospital-approved value in W.
- Efficiency: enter the measured, quoted, or hospital-approved value in %.
Result interpretation
- Usable energy is an estimate, not a guaranteed clinical runtime.
- Estimated runtime should be verified for critical biomedical devices.
Assumptions
- Real runtime depends on battery age, chemistry, temperature, and discharge curve.
- Verify critical equipment runtime with actual load testing.
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 and common working ranges to choose values from gauges, labels, manuals, datasheets, RFQs, service reports, CMMS records, or hospital planning assumptions.
| Field | Example value | Common range | Tip |
|---|---|---|---|
| Battery voltage | 12 V battery pack. | Common batteries are 12 V blocks; UPS strings may be 24, 48, 96 V, or higher. | Use total battery bank voltage if batteries are wired in series. |
| Battery capacity | 7 Ah printed on sealed lead-acid battery. | Small SLA batteries are often 7-18 Ah; larger packs may be 40-200 Ah or more. | Use rated Ah only for healthy batteries; derate old batteries. |
| Load | Infusion pump 20 W or monitor 80 W. | Small medical devices may be 20-500 W; workstations, UPS loads, and carts may be 300-2,000 W. | Use measured watts where possible; nameplate values may not represent real running load. |
| Efficiency | 90% for a simple DC system; 80-85% for inverter-backed loads. | Many battery runtime estimates use 80-95% depending on inverter and DC losses. | Use the vendor value if known; otherwise use a conservative planning value. |
Common ranges are starting points for hospital planning. For final procurement, acceptance testing, electrical design, medical gas design, radiation shielding, dialysis water systems, or clinical use, replace the example values with site-specific data and vendor-confirmed figures.
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.
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