Winter storm home backup power plan

Start with the appliances that matter

A winter storm can cut electricity while your household still needs heat, water, food storage, communication and medical devices. A portable power station can run compatible appliances during the outage, but its stored energy is limited, so a multi-day plan has to account for both battery capacity and recharging. Start by deciding which equipment must stay available.

This is a planning list, not a claim that every power station can run these appliances. Record the specifications of your own equipment before buying backup power.

Make a plan for a multi-day outage

Start with how long each essential appliance needs to run. Some need continuous power, while others run on and off. For a simple energy estimate, multiply average power by operating time: Energy needed (Wh) = Average power (W) × Operating hours. Then add up the results for every appliance you expect to use.

Our runtime calculations assume that 80% to 90% of rated battery capacity reaches connected AC appliances:

• Lower estimate = Rated battery Wh × 0.80
• Upper estimate = Rated battery Wh × 0.90

Divide that estimated available energy by the average connected load to get a runtime range. The calculation doesn't tell you whether the station can start a given appliance. Our runtime calculator and size calculator walk through your household's numbers.

Prioritize heating system controls

A gas furnace may need electricity for its controls, fans and blower even though the heat itself comes from gas. Don't assume a portable battery can run your furnace just because its continuous AC output looks high enough. Check the furnace's electrical specifications, including running and startup requirements, and whether it needs a particular electrical connection or has other compatibility conditions.

If the furnace is wired into the house, supplying it through the home's circuits requires listed transfer equipment installed by a licensed electrician with any required permit. Read our transfer switch guide before planning circuit-level backup.

Why electric space heating drains batteries

Electric resistance heating uses far more energy than small household electronics. A heater drawing 1,500W continuously for 8 hours needs 1,500W × 8 hours = 12,000Wh, or 12kWh, and that's the energy delivered to the heater before battery and inverter losses. Compare it with these manufacturer-rated capacities:

Every base unit listed holds less than the 12,000Wh in the example, which is why running a resistance heater for hours can empty a portable battery quickly. Expansion batteries add energy, but total capacity and continuous output still have to match the load.

If you do use a space heater, the CDC advises keeping it at least 3 feet from drapes, furniture, bedding and other flammable materials. Never use a stove to heat your home.

Plan for water needs

If your home relies on an electric well pump, a power outage can also cut off your water. A pump may need 240V output and substantial starting current, so a station with enough rated battery capacity may still be unable to start it. Check the pump or control box nameplate against the backup source's voltage and surge capabilities. A pressure tank affects how often the pump runs, so estimate pump runtime from actual demand and operation. Battery backup for a well pump covers the sizing in detail. For other water equipment, work out which parts depend on electricity and add their requirements to your plan.

Protect refrigerated and frozen food

FoodSafety.gov gives these outage guidelines for food storage:

• An unopened refrigerator keeps food cold for about 4 hours.
• A full closed freezer holds temperature for about 48 hours.
• A half-full closed freezer holds temperature for about 24 hours.

Keep the refrigerator and freezer doors closed as much as you can. These figures describe how long food stays cold without power, not how long a battery will run a particular appliance. Battery runtime depends on the appliance's energy use and the power station's usable energy, and for a refrigerator you need to check both average consumption and compressor startup requirements. Our refrigerator backup guide shows how to estimate the energy requirement.

Keep communications and medical equipment available

For phones and internet equipment, list what you want to power and how long it has to run. Medical devices need closer checks. A power station's advertised UPS or EPS transfer time doesn't by itself establish uninterrupted operation with a particular device, so check the equipment manufacturer's backup requirements and make a separate plan for any device that can't safely tolerate an interruption. For CPAP-specific planning, see power stations for CPAP.

Plan how to recharge

A charged battery holds a finite amount of energy, so a long outage means recharging. The options depend on the station:

• Household AC charging when electricity returns
• Compatible vehicle charging
• Solar charging with suitable panels
• Charging from a compatible fuel generator

A station's maximum solar input isn't a promise of what panels will produce during a storm. Weather, available sunlight and charging conditions all affect output, so don't build your plan around an assumed winter solar output without supporting data.

Cold-weather battery charging

Each manufacturer specifies charging temperature limits in its documentation, so check the manual for your exact model before charging in the cold. A battery's permitted operating temperature isn't necessarily the same as its permitted charging temperature. Follow the manufacturer's instructions for battery storage, ventilation and operation as well.

Carbon monoxide and generator safety

Fuel-burning equipment brings carbon monoxide risk into an outage. The CDC advises keeping portable generators outside, at least 20 feet from doors, windows and vents. Also:

• Never operate a generator inside the home.
• Never run a generator inside a basement, garage or other enclosed structure, even with doors or windows open, unless professionally installed and vented (CDC).
• Never use a grill or camp stove indoors.
• Never use the stove for home heating.
• Install a battery-operated carbon monoxide detector.

A battery power station produces no combustion exhaust while running from its battery, but it still has to be operated according to the manufacturer's instructions. If you plan to combine a generator and a battery system, read our power station vs gas generator guide.

Review the plan before the storm

A useful plan covers what must run, how much energy it needs, and what happens when stored power runs low. Before relying on your system, check that:

• Essential appliances are identified.
• Running and startup requirements are recorded.
• Battery capacity has been compared with expected consumption.
• Medical-device compatibility has been checked.
• Cold-weather charging limits have been reviewed.
• Recharging options are understood.
• Fuel-burning equipment has a safe outdoor operating location.
• Any household circuit connection has been assessed by a licensed electrician.