Jackery Portable Power Supply: How to Size One for Home Backup (2026)

By Graham Fisher

Updated November 2026

A jackery portable power supply can keep a refrigerator, a CPAP machine and a sump pump running through a typical power outage, but only if you size it correctly. In this guide you will total the watt-hours your essential loads actually use, compare that number against a Jackery model’s rated capacity, and add a practical margin for inverter losses and bad weather. The method works whether you already own a unit or are still shopping.

Step 1: List the Loads You Really Need

Start with a short list of devices you want running during an outage. Resist the urge to include everything in the house. A portable power station is a bridge for essentials, not a replacement for your whole electrical system. For most households, the list begins with a refrigerator, a few LED lights, phone and laptop charging, a Wi-Fi router, and any medical device such as a CPAP. Sump pumps are a common addition in basements prone to flooding.

Write down each device and check its label. Look for a wattage rating, sometimes listed in amps and volts instead. If the label shows amps, multiply amps by volts to get watts. A label reading 1.2 A at 120 V means roughly 144 watts while running.

Running Watts vs. Starting Watts

Motors draw a surge of power when they start. Refrigerator compressors, well pumps and sump pump motors can need two to three times their running wattage for a moment. Your power station needs to handle that surge, so check its surge or peak rating against the largest motor on your list. Manufacturers usually publish both continuous output and surge capacity in the product specifications.

Step 2: Convert Watts to Watt-Hours

Watt-hours (Wh) are the unit that matters for runtime. Multiply each device’s wattage by the hours it will run per day. Then add the totals together.

A simple formula works for most planning: Daily Wh = Watts × Hours per day. Compressors do not run continuously, so for a refrigerator you can estimate the duty cycle. Many fridges run roughly 30 to 50 percent of the time, depending on ambient temperature, door openings and the unit’s efficiency. Use your appliance’s energy label, which in the US lists estimated annual kilowatt-hours, to get a closer figure. Divide that annual kWh by 365 and multiply by 1,000 to convert to a daily Wh estimate.

Worked Example

In this example the household needs close to 3,000 watt-hours per day. The fridge dominates the total, which is typical. Mentally round up and plan around that number.

Step 3: Account for Conversion and Battery Losses

No power station delivers its full rated capacity to your devices. Energy is lost in the inverter that converts stored DC power to household AC power, and some is lost in charging and discharging. Many manufacturers rate their units in a way that already reflects typical usable energy, but real-world results often come in below the headline figure. A reasonable planning assumption is that you will get roughly 80 to 85 percent of the rated watt-hours to your appliances.

Also plan for the battery’s depth of discharge. Lithium iron phosphate batteries, which many portable stations use, tolerate deep cycling well, yet running a battery down to zero every day shortens its life. Some owners prefer to stop around 10 percent state of charge during extended outages.

Applying the Margin

Take your daily Wh total and divide by 0.85 to estimate the capacity you need from the battery. In the example above, 2,960 ÷ 0.85 is about 3,480 Wh. A unit with at least 3,600 Wh of rated capacity would cover one day with a small buffer. For two days, you would need roughly 7,000 Wh, which points toward a larger model or a stack of batteries.

Step 4: Choose a Model That Fits Your Numbers

Once you know your daily watt-hour need, match it to a Jackery product line. Jackery sells portable power stations across a wide range of capacities, from compact units suited to phones, lights and small fans, to larger systems designed for refrigerators and medical equipment. Compare rated capacity, continuous output, surge rating, number of outlets and recharge options such as wall, car and solar input.

If you are not sure where to start, browse the comparisons on this site. Our guide to 6 Best Jackery Explorer 300 Portable Power Station Models for Home Backup (2026) covers mid-size options for essential loads, while 5 Best Jackery Portable Power Station Models for Home Backup (2026) looks at a broader range. For larger whole-circuit planning, see Jackery Solar Generator Home Power 3000: 4 Best Options Compared (2026).

Check the Output Ratings

Capacity alone is not enough. A unit that stores plenty of energy can still fail to start a compressor if its continuous output is too low. Confirm that the continuous AC output exceeds the combined running watts of everything you plan to run at the same time, and that the surge rating covers your largest motor’s startup draw.

Step 5: Plan Recharging

A power station is only useful if it can be refilled. During a multi-day outage, you may need to recharge from solar panels, your car, or a generator. Wall charging is fastest when grid power exists, but it is not an option during a blackout. Solar input depends on panel wattage, sun hours and weather.

To estimate solar recharge time, divide the battery’s usable Wh by the panel’s realistic daily output. A 400-watt panel in good sun might produce around 1,200 to 1,600 Wh on a clear day, though results vary widely by season, angle and shading. For sizing guidance, see Solar Panel Size Calculator for Portable Power Stations. For charging from a vehicle, the Jackery Car Charging Cable: How to Charge Your Power Station From a Car article explains the setup and its limits.

Step 6: Use the Unit Safely

Portable power stations contain lithium batteries and high-current electronics. Keep them dry, indoors or under cover, and out of direct sun. Do not block vents. Never plug a power station into a home’s wall outlet to backfeed the house. That can injure utility workers and damage equipment. Use a properly installed transfer switch or a dedicated interlock kit if you want to power circuits directly, and have a licensed electrician do that work.

For more on battery handling and storage, read Lithium Battery Safety for Portable Power Stations.

Common Mistakes

• Ignoring surge ratings. A well pump or sump pump may trip the unit if the surge exceeds the output limit.
• Using nameplate watts for everything. Fridges and pumps cycle, so their real daily Wh is usually lower than running watts multiplied by 24 hours. Equally, forgetting that they run more on hot days can leave you short.
• Forgetting inverter losses. Planning to the exact rated capacity almost always leaves you short.
• Running a space heater or electric dryer. These draw far more energy than a typical portable station can supply for long.
• Waiting until the outage to test. Run each device on the unit for an hour now to confirm it works.

Tips for a Reliable Setup

1. Keep the unit charged above 50 percent during storm season.
2. Label the outlets you use for medical devices so family members know which ones to protect.
3. Store a spare charging cable and a basic adapter with the unit.
4. Recheck your load list every year, because new devices quietly increase demand.
5. If you depend on a CPAP or other powered medical equipment, talk with your doctor or equipment supplier about backup plans before you need them.

Recommended gear

These items support the sizing and charging steps above. Confirm compatibility with your specific Jackery model before buying.

• Plug-in watt meter. Measures the real draw of your fridge, CPAP and other devices, which is more accurate than label estimates. View on Amazon
• Solar panel for portable power stations. Helps extend runtime during multi-day outages when grid charging is unavailable. View on Amazon
• Car charging cable for portable power stations. Gives you a backup recharge path when solar is limited. View on Amazon

FAQ

How many watt-hours do I need to run a refrigerator overnight?

Most full-size refrigerators use somewhere between roughly 1,000 and 2,000 Wh per day, depending on size, efficiency, room temperature and how often the door opens. Check the appliance’s energy label for an estimate, then confirm with a plug-in watt meter if you can.

Can a Jackery portable power supply run a CPAP all night?

Many CPAP machines draw roughly 30 to 90 watts while running, so an eight-hour night often needs a few hundred watt-hours. A mid-size unit can typically cover several nights, but confirm the exact draw of your model and consult your doctor or durable medical equipment supplier about backup planning.

Is it safe to keep a power station indoors?

Yes, when used according to the manufacturer’s instructions. Keep it in a dry, ventilated area away from heat sources and flammable materials, and avoid charging it under a blanket or in an enclosed cabinet.

Can I run a sump pump from a portable power station?

Often yes, but it depends on the pump’s starting surge and its daily run time. Check the surge rating against the pump’s startup draw, and estimate its runtime during heavy rain to size the battery correctly.

How long does it take to recharge from solar?

It depends on panel wattage, sun hours, weather and the unit’s maximum solar input. Divide the usable battery capacity by your realistic daily panel output to estimate how many sunny days you need.

Can I plug a Jackery into my home’s outlets to power the house?

Not safely without a proper transfer switch or interlock installed by a licensed electrician. Never backfeed a home’s wiring from a standard outlet, because it can endanger utility workers.

How often should I recharge the battery during storm season?

Keeping the battery above about 50 percent before forecasted storms is a common practice. Recharging to full when grid power is stable also helps you start an outage with the most available energy.

Conclusion

A jackery portable power supply works best when you size it from real numbers: list the essential loads, convert them to daily watt-hours, and add a margin for inverter losses. Check surge and continuous output, plan at least one recharge method, and test the setup before an outage. Consult a qualified electrician for any transfer switch or whole-home connection, and a medical provider for life-support planning.

About Graham Fisher

Graham Fisher is part of our editorial team and reviews and edits our solar generators for home backup & emergencies guides, checking product details against manufacturer specifications and owner feedback.