What 2 kWh Will and Won’t Run

Portable power stations of about 2 kWh have become the usual first step into home backup. They are big enough to keep a refrigerator, the internet and a CPAP going through a typical outage, light enough to carry from the closet (about 35 to 55 pounds) and priced from about $650 to $1,000 in October 2026. Whether 2 kWh is enough for your house depends entirely on what you plug into it. Here is the arithmetic, using figures from appliance makers and federal efficiency data, so you can check it against your own home.

Start with usable energy, not the number on the box

A “2 kWh” battery does not deliver 2 kWh to your appliances. The inverter that turns battery power into household 120-volt AC loses some along the way, so plan on about 85 percent, the factor Jackery uses in its own runtime formula. A 2,000Wh unit therefore gives you roughly 1,700Wh of usable AC power.

The formula is simple: runtime in hours = usable watt-hours ÷ the appliance’s average watts.

Two numbers on the spec sheet matter. Capacity, in watt-hours, tells you how long things run. Continuous output, in watts, tells you what can run at the same time; most 2 kWh units deliver 2,000 to 2,600W. Motors in fridges and pumps also need a brief start-up surge. Some units advertise a “power lifting” mode that lets heaters and kettles run at reduced power above the rated output, but that does not help motors start.

What 2 kWh will run

A refrigerator. ENERGY STAR’s product data puts the median full-size refrigerator (18 to 28 cubic feet) at 553 kWh a year. That is an average of about 63 watts, or 1.5 kWh a day, because the compressor cycles on and off. On 1,700Wh, a modern fridge runs about 27 hours. Older models use more: find the kWh-per-year figure on the yellow EnergyGuide label and divide by 8,760 to get your fridge’s average watts. Honda’s wattage guide puts an efficient fridge’s start-up draw at about 1,200W, well within any 2 kWh unit.

Internet. Champion’s wattage chart lists a Wi-Fi router at 10 to 20 watts, so a router alone runs for days. A Starlink Standard dish averages 75 to 100 watts by Starlink’s own specifications, which works out to roughly 17 to 23 hours.

A CPAP. In ResMed’s battery guide, an AirSense 10 draws about 8 to 20 watts through ResMed’s DC converter with the humidifier off, and 41 to 55 watts with the humidifier on. A night of 8 hours at 20 watts uses 160Wh, so 1,700Wh covers about 10 nights. With the humidifier at 55 watts, it is closer to 4 nights. ResMed recommends its DC converter over running the machine through an inverter, which wastes power.

Short bursts in the kitchen. Honda lists a 1,000-watt microwave as drawing about 1,500 watts. Ten minutes of reheating uses about 250Wh, so a few meals a day are affordable as long as you leave room for the fridge.

What 2 kWh won’t run for long

Sump pumps. Honda’s guide lists a 1/3 horsepower pump at about 800 watts running and 1,300 watts to start, and a 1/2 horsepower pump at about 1,050 running and 2,150 to start. A 2 kWh unit can start either, but 1,700Wh is only about two hours of continuous pumping. In a storm, a pump cycles on and off, so the battery lasts longer than that, but plan to recharge it or step up to a bigger, expandable system if your basement floods regularly.

Oxygen concentrators. A home unit such as the Philips EverFlo averages about 350 watts, so a 2 kWh battery gives under five hours. Treat it as a bridge and ask your equipment supplier about backup cylinders.

240-volt appliances. Central air conditioning, electric water heaters, ranges, dryers and many well pumps run on 240-volt circuits, and most 2 kWh units have only 120-volt outlets. These loads need a larger home battery or a generator.

Heat. A 1,500-watt space heater empties a 2 kWh battery in about an hour. A gas furnace’s blower is a better use of the energy (Honda lists a 1/2 horsepower blower at about 875 watts running), but furnaces are hardwired, so connecting one requires an electrician and a transfer switch or inlet.

A realistic outage day

Add up a modest essentials list: a modern fridge (1.5 kWh a day), a router running around the clock (about 0.5 kWh), a CPAP for one night with the humidifier off (0.16 kWh) and phone and laptop charging (perhaps 0.1 kWh). That comes to about 2.2 kWh a day, a little more than the 1,700Wh a 2 kWh unit actually delivers. On battery alone, that list runs about 18 hours. With a few hundred watts of solar panels and a sunny afternoon, you can put back much of a day’s use, which is why most 2 kWh units accept solar input.

How to choose

• Chemistry and cycles. Look for LiFePO4 (lithium iron phosphate) cells rated for 3,000 cycles or more; they last longer and are more heat-tolerant than older lithium-ion chemistries.
• Continuous output above your biggest start-up surge. A fridge plus a sump pump starting at the same moment is the test.
• Solar input and charging speed. Higher solar input refills the battery faster between outages.
• Expansion. If your list might grow, choose a unit that accepts add-on batteries.
• DC outputs. A 12-volt outlet lets a CPAP run on its DC cable, which saves power.

A 2 kWh unit such as the BLUETTI Elite 200 V2, for example, pairs 2,073.6Wh of LiFePO4 storage with 2,600W of continuous output, 1,000W of solar input and a 6,000-cycle rating for about $899. It has no add-on battery, so it suits households whose essentials already fit inside 2 kWh. If yours do not, the list above shows where the extra energy is going, and that is the place to start.

Brian is the editor of SolarGenReview, which covers portable power stations and home backup for US buyers.