Medical Preparedness · Medical Devices and Power
Backup Batteries and Portable Power for Medical Devices
How to size a battery backup for the medical devices in your household, choose the right type of system, and test it before the outage happens.
Planning guidance, not medical advice
This page helps you plan backup power for medical devices. It does not provide medical advice, clinical instruction, or treatment recommendations. Consult your doctor, your home medical equipment supplier, and the device manufacturer about your specific power needs before making any changes to your medical routine or supply.
What this guide covers
The math, the choices, and the test run that stand between your household and a dark, quiet night with a device that needs electricity.
If a power outage lasts four hours, most households notice the inconvenience. A household with a CPAP machine, an oxygen concentrator, a powered wheelchair, or a home dialysis system notices a threat. The difference between the two is whether backup power exists and whether someone tested it before the storm arrived.
FEMA and the American Red Cross both recommend that households with power-dependent medical equipment have backup power for a minimum of 72 hours.1 Ready.gov advises purchasing extra batteries for battery-operated medical and assistive technology devices and talking to your doctor about a power-outage plan for each device that needs electricity.2,3
This guide walks through the sizing math, the types of backup systems, the pure sine wave requirement, and the testing process. It does not recommend specific brands or models. Your home medical equipment supplier and your device manufacturer are the starting points for compatibility questions.
What this page does not cover: The overall power outage planning process (see Power Outage Planning for Medical Devices), generator safety (see Generator Safety for Medical Users when available), or the decision about when to leave home (see When to Relocate Before an Event when available). For a broader look at backup power beyond medical devices, see the Energy section.
Step 1
Calculate how much power you actually need
Every battery backup conversation starts with one number: how many watt-hours your device uses in the time period you need to cover. The formula is simple. The discipline is in reading the label rather than guessing.
The formula
(Device watts) x (Hours of use) x 1.15 = Minimum battery capacity in watt-hours
The 1.15 multiplier accounts for the efficiency loss when a battery's inverter converts stored DC power to the AC power your device uses. About 10 to 15 percent of the stored energy is lost in that conversion. Without this adjustment, a battery that looks large enough on paper runs out sooner than expected.
Where to find the wattage: Look at the label on the back or bottom of the device, or on the power supply brick. It will show watts (W) directly, or it will show volts (V) and amps (A), which you multiply together to get watts. If the label shows a range, use the higher number for planning.
CPAP machine (nighttime use)
Typical draw: 30 to 60 watts without heated humidifier, 50 to 100 watts with heated humidifier and heated tube.
One night (8 hours) at 60 watts: 60 x 8 x 1.15 = 552 watt-hours.
A portable power station rated at 500 to 1,000 watt-hours covers one night for most CPAP machines. Turning off the heated humidifier cuts power consumption roughly in half and extends runtime substantially.
Home oxygen concentrator (continuous use)
Typical draw: 300 to 600 watts, running continuously.
One full day (24 hours) at 350 watts: 350 x 24 x 1.15 = 9,660 watt-hours.
This is sobering math, and it is honest. No single portable power station covers a home oxygen concentrator for a full day. A battery can bridge a few hours while the grid comes back, a generator starts, or you switch to backup oxygen cylinders from your home medical equipment supplier. For extended outages, a battery is one layer of a plan, not the whole plan. Coordinate with your physician and your oxygen supplier.
Powered wheelchair or scooter
Most powered wheelchairs have their own batteries and their own chargers. The planning question here is not "what runs the chair" but "what charges the chair when the outlet is dead."
Read the charger's label for its wattage, multiply by the hours a full charge takes, and size your backup to cover at least one full charge cycle. Ready.gov also recommends keeping a lightweight manual chair available as a backup if your household has one available.2
List every device. Before shopping, write down every power-dependent medical device in your household, its wattage, and the hours per day it runs. This is the inventory that drives every decision that follows. Your household medical profile should include this information.
Step 2
Choose the right type of backup
Three categories of battery backup serve different roles. Many households with medical devices end up using more than one.
Uninterruptible power supply (UPS)
A UPS sits between the wall outlet and the device, providing instant switchover when power drops. There is no gap, no restart, no interruption. This matters most for devices that cannot tolerate even a momentary loss of power, such as ventilators or powered infusion pumps.
The tradeoff is capacity. Most consumer UPS units hold 300 to 1,500 watt-hours, which provides minutes to a few hours depending on the device's draw. A UPS is a bridge, not a destination. It keeps the device running while you start a generator, switch to a larger battery, or execute your relocation plan.
Best for: Devices that must never lose power, even for a fraction of a second. Often used as the first line of defense alongside a larger backup system.
Portable power station
A portable power station is a large, rechargeable battery with built-in outlets. Capacities range from about 300 watt-hours for compact units to over 3,000 watt-hours for large ones, with some models supporting expansion batteries that push capacity much higher. They recharge from a wall outlet, a car's 12-volt port, or solar panels.
For a CPAP machine, a mid-range portable power station provides one to three nights of backup. For an oxygen concentrator, even a large station provides only a few hours, which is still valuable as a bridge. Some models offer a UPS-like passthrough mode that switches to battery automatically when power drops, though the switchover is usually slower than a dedicated UPS.
Best for: Overnight and multi-day backup for moderate-draw devices like CPAP machines, nebulizers, and powered wheelchair chargers. Also portable enough to bring during an evacuation.
Vehicle power (12-volt inverter)
A car battery connected through an inverter can power medical devices as a last resort. A typical car battery holds about 600 to 800 watt-hours of usable energy. With the engine running, the alternator continuously recharges the battery, providing effectively unlimited power as long as there is fuel.
Important: Never run a vehicle engine in an enclosed space. Carbon monoxide is deadly. If using vehicle power, the car must be outdoors in open air. See Generator Safety for Medical Users (when available) for detailed CO safety guidance. Also confirm that the inverter you use produces pure sine wave output, not modified sine wave.
Step 3
Two things to get right before you buy
Pure sine wave output
The electricity from a standard wall outlet follows a smooth waveform called a pure sine wave. Medical devices with motors, microprocessors, and heating elements are designed to operate on this smooth power. A pure sine wave inverter replicates it. A modified sine wave inverter produces a rougher, stepped waveform that can cause buzzing, excess heat, reduced efficiency, and in some cases damage to the device.
Multiple CPAP manufacturers specify pure sine wave power in their backup compatibility guidelines. Oxygen concentrators, nebulizers, and most other motorized medical devices also benefit from or require it.4
All modern portable power stations from major manufacturers produce pure sine wave output. The risk comes from older or budget inverters. If you are using any inverter, confirm it says "pure sine wave" on the specifications. If the documentation does not explicitly say it, assume it is modified sine wave and avoid it for medical use.
Test the system before you need it
The ADA National Network's emergency power planning checklist recommends reviewing and updating your power backup plan every six months.5 That review should include a live test: unplug your device from the wall, plug it into the battery, and run it through a normal use cycle. For a CPAP, that means a full night. For a wheelchair charger, a full charge. Time how long the battery lasts and compare it to your sizing math.
A system you have never tested is a system you do not know works. Every part of the chain matters: the battery itself, the cable, the outlet, the device's response to a different power source. Some devices display a warning when running on battery. Some change their behavior. You want to discover these things on a calm evening, not during a hurricane.
After each test, recharge the battery fully. Lithium batteries in portable power stations hold their charge well for months, but confirm the charge level before each storm season and after any extended period of non-use.
Solar as a recharge option
Many portable power stations accept solar panel input. During an extended outage, solar panels can recharge the battery during daylight hours, extending coverage across multiple days. A 200-watt solar panel in good sun can add roughly 800 to 1,000 watt-hours over a full day of sunlight. This is enough to recharge a CPAP backup overnight. It is not enough to keep up with a high-draw oxygen concentrator, but it extends the bridge. For a deeper look at solar as a backup power source, see the Energy section.
Common questions
Frequently asked questions
What size battery backup do I need for a CPAP machine?
A CPAP typically draws 30 to 100 watts depending on model and settings. For one night (8 hours) at 60 watts: 60 x 8 x 1.15 = roughly 552 watt-hours. A portable power station rated at 500 to 1,000 watt-hours covers one night for most models. Turning off the heated humidifier can cut power draw roughly in half. Check your device's power supply label for the specific wattage.
Can a portable power station run an oxygen concentrator?
For a few hours, yes. A home oxygen concentrator draws 300 to 600 watts continuously, using 7,200 to 14,400 watt-hours per day. No single portable power station covers that for a full day. A battery buys time while the grid comes back, a generator starts, or you switch to backup oxygen cylinders. For extended outages, pair a large battery with solar panels and keep backup oxygen tanks from your supplier. Always coordinate with your physician.
Why do medical devices need a pure sine wave inverter?
Medical devices with motors, microprocessors, or heating elements are designed for the smooth AC waveform from a standard wall outlet. Modified sine wave inverters produce a rougher waveform that can cause buzzing, excess heat, and equipment damage. Multiple CPAP manufacturers specify pure sine wave power.4 All modern portable power stations from major manufacturers produce pure sine wave output. Older or budget inverters may not.
Should I use a UPS or a portable power station?
A UPS provides instant switchover with no gap in power, which matters for devices that cannot tolerate any interruption. A portable power station provides much more capacity for longer runtime but may have a brief switchover delay. For life-critical devices, use a UPS as the first line plus a larger system for duration. For a CPAP, which restarts without harm, a portable power station alone is usually sufficient.
How do I calculate the battery capacity I need?
Read the wattage from your device's power supply label. Multiply by hours of use. Multiply by 1.15 for inverter efficiency loss. The result is your minimum battery capacity in watt-hours. Example: 60 watts x 8 hours x 1.15 = 552 watt-hours minimum. Round up to the next available battery size for margin. For households with multiple devices, add the watt-hour needs together.
Sources
- 1. Texas Governor's Committee on People with Disabilities. "Emergency Solutions for Powering Durable Medical Equipment." April 2022. Accessed September 4, 2026. Citing FEMA and American Red Cross 72-hour individual preparedness recommendations. gov.texas.gov/.../Slides-Emergency-Power-Solutions-for-DME
- 2. Ready.gov. "People with Disabilities." U.S. Department of Homeland Security. Accessed September 4, 2026. ready.gov/people-disabilities
- 3. FEMA. "Be Prepared for a Power Outage." V-1008, December 2023. Accessed September 4, 2026. ready.gov/...power-outage_hazard-info-sheet.pdf
- 4. CPAP manufacturer backup power guidelines. ResMed AirSense series and Fisher & Paykel SleepStyle both specify pure sine wave inverter requirements in their power compatibility documentation. Accessed September 4, 2026. Check your specific device manufacturer's documentation.
- 5. ADA National Network. "Emergency Power Planning for People Who Use Electricity and Battery-Dependent Assistive Technology and Medical Devices." Pacific ADA Center. Accessed September 4, 2026. adata.org/factsheet/emergency-power
Who to contact
Your home medical equipment (HME) supplier: The first call for backup power compatibility, backup oxygen cylinders, and device-specific guidance. They know your equipment and can recommend compatible battery systems.
Your device manufacturer: Check the manufacturer's documentation or support line for specific inverter requirements, battery compatibility, and recommended backup configurations for your model.
Your prescribing physician: Coordinate your overall power outage plan with your doctor, especially for life-sustaining equipment. They can help determine how long you can safely operate without the device and when to relocate.
Your utility company: Register as a medical priority customer for priority power restoration. See Utility Medical Priority Programs (when available).
Related guides
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"It is better to look ahead and prepare than to look back and regret."
Jackie Joyner-Kersee