Medical Equipment & Emergency Battery Backup Runtime Calculator

Emergency Preparedness & Healthcare: Battery Power for Medical Devices

For patients dependent on life-sustaining medical equipment, planning emergency backup power is vital:

• Battery Chemistries:

• LiFePO4 (Lithium Iron Phosphate): 3,500+ lifecycle charges, safe 90% Depth of Discharge (DoD), no thermal runaway.

• Lead-Acid / AGM: Heavy, damaged if discharged past 50% DoD.

• CPAP Power Saving Tip: Turning off the heated tube and heated humidifier reduces CPAP power draw from ~60W down to only 15W–20W, tripling battery backup runtime.

How to Use This Calculator

Enter your Medical / Critical Device Preset — select from CPAP Machine with Heated Humidifier (60 Watts), CPAP / BiPAP (No Humidifier | 20 Watts), Home Oxygen Concentrator (350 Watts), Continuous Device Power Draw (Watts [W]) (e.g. 60 (60 Watts CPAP draw)), Battery Bank Chemistry — select from Lithium Iron Phosphate (LiFePO4 - 90% Usable DoD), Lithium-Ion Portable Power Station (NMC - 85% Usable DoD), Deep Cycle AGM / Gel Lead-Acid (50% Usable DoD Limit), Battery Capacity Input Unit — select from Watt-Hours (Wh [e.g. 1000 Wh Portable Station]), Amp-Hours at 12 Volts (Ah @ 12V [e.g. 100 Ah = 1200 Wh]), Nominal Battery Capacity (Wh or Ah) (e.g. 1,000 (1,000 Wh battery pack or 100 Ah 12V)), and Inverter DC-to-AC Conversion Efficiency (%) (e.g. 88 (85%–92% pure sine wave inverter)). Results update instantly — no submit button needed. Use metric or imperial units as labeled. For the most accurate result, measure height and weight in the morning without shoes.

The Formula

Battery Runtime equations:

Total Nominal Energy (Wh) = Ah × Voltage (V) (or direct Wh)

Usable Energy (Wh) = Total Wh × DoD (\%) × Inverter Efficiency (\%)

Backup Runtime (Hours) = (Usable Energy (Wh)) / (Continuous Device Power (Watts))

8-Hour Sleep Cycles = (Runtime (Hours)) / (8)

Worked Example

For example, powering a 60 Watt CPAP machine with heated humidifier during a power outage using a 1,000 Wh LiFePO4 portable power station (90\% usable DoD, 88\% pure sine inverter efficiency): Usable energy is . Total backup runtime is \ (1.65 full 8-hour nights of sleep).

Understanding Your Result

NIAA defines heavy drinking as more than 4 drinks on any day or 14 per week for men, or more than 3 drinks on any day or 7 per week for women. Blood Alcohol Concentration (BAC) of 0.08% is the legal driving limit in the US — impairment of judgment and reaction time begins at 0.02–0.04% BAC. Liver metabolizes approximately 1 standard drink per hour regardless of coffee, food, or exercise. BAC calculators use population averages — individual variation in alcohol dehydrogenase enzyme activity can cause significant departures from estimated values.