Power outage backup kit: keep your smart home and Wi-Fi going
Updated
Six essentials to keep Wi-Fi, lighting, phone charging and alerts working when the power fails, plus options for a longer outage. Prices, sizing questions and a short test routine are included.
As an Amazon Associate we earn from qualifying purchases. Links to Amazon on this page are affiliate links: buying through them costs you nothing extra.
Before you buy
Decide what you are protecting
List three things you cannot go without in an outage: usually lights, phone charging and communication, and the refrigerator. A fourth might be heating or cooling, which is beyond what a small battery can do. Match the battery to that list, not to every smart device in the house. Our UPS runtime calculator shows how long a given battery lasts for your router, modem and hub.
What stays smart during an outage
| Device | Without power | With router and hub on a UPS |
|---|---|---|
| Battery sensors and locks (Zigbee, Z-Wave, Thread) | Keep working on their own batteries, but need a powered hub or border router to report | Keep reporting to your hub, and to your phone as long as the internet and cell network are up |
| Wi-Fi cameras, plug-in sensors, smart plugs | Plug-in devices stop | Only devices on the UPS keep running; the rest stay off |
| Smart bulbs and switches | No light | No light unless the bulb is powered; check how your bulbs behave when power returns, see smart bulbs after a power outage |
| Thermostat | Battery or system power needed; many keep their settings | The furnace or AC still needs line power |
| Voice assistants | Plug-in speakers stop | Work only if the speaker, hub and internet are all powered |
Safety first: generators and batteries
FEMA says to use generators outdoors and at least 20 feet away from building openings such as windows, doors and garages. The Consumer Product Safety Commission adds that portable generators must never run inside a home or garage, even with doors and windows open, because they produce carbon monoxide. Connecting a generator to your house wiring needs a properly installed transfer switch: turn off the main breaker, and hire a licensed electrician and follow local code. Never plug a generator into a wall outlet to power the house.
Lithium-ion batteries in power banks and power stations should be charged with the supplied charger, never left charging unattended, kept in a cool dry place and charged only between 32°F and 105°F, according to New York State’s consumer guide.
Food in the fridge and freezer
FoodSafety.gov says a closed refrigerator keeps food safe for up to 4 hours, a full freezer for about 48 hours and a half-full freezer for about 24 hours. FEMA says to discard refrigerated food that has been above 40°F for more than 4 hours. Keep doors shut and check the thermometer. A smart fridge alarm is covered in our fridge and freezer alarm guide.
If someone depends on medical equipment
A router UPS or small power station is not a medical backup. FEMA recommends talking to your doctor to make a plan for devices that need electricity, including how to store medications. The HHS emPOWER Program works with public health agencies to protect people who live independently and rely on electricity-dependent medical and assistive equipment. Also ask your electric utility whether it keeps a medical-needs list and what its advance notice is for planned shutoffs.
Smoke alarms need power too
Hardwired smoke alarms have backup batteries. The U.S. Fire Administration says to test alarms monthly and replace the entire alarm every 10 years. Check them before storm season.
Core items
Battery backup (UPS) for the modem and router
$40–$150Keeps your internet connection, hub and any Wi-Fi sensors and locks reachable through short outages. Most of the smart home stops being useful when the router goes dark.
What to look for: a battery you can size in watt-hours, an output rating comfortably above your modem, router and hub load, or a mini DC UPS that matches your router’s voltage and plug; a replaceable battery; a recognized safety certification
See options on AmazonRechargeable LED lanterns × 2
$15–$40Flashlights, lanterns and other battery-powered lights are the recommended way to light a home in an outage. Smart bulbs need power and, often, a working router.
What to look for: USB rechargeable, low-light mode that runs for many hours, stands on a table, lithium battery from a recognized maker
See options on AmazonPower banks for phones × 2
$20–$50Your phone is the remote control, the alert receiver and the hotspot. Keep two charged so one can stay with a family member.
What to look for: 10,000 mAh or more, a USB-C output that also charges the phone, recognized safety marks, a recent charge date on your calendar
See options on AmazonBattery-backed carbon monoxide alarms × 2
$25–$60Generators, camp stoves and grills used indoors during outages are a known carbon monoxide risk. FEMA advises battery-backed alarms on every level and near sleeping areas.
What to look for: UL-listed, battery backup or battery-only, interconnected or connected wireless option, an end-of-life date printed on the unit
See options on AmazonPower-loss alert sensor
$25–$70Tells you when power drops at home, which matters most if you are away. It needs a battery of its own and either a cellular link or a router on a UPS.
What to look for: built-in battery, phone notification when power is lost and when it returns, cellular or Wi-Fi connection that you can keep powered
See options on AmazonAppliance thermometers for refrigerator and freezer × 2
$8–$20Food safety after an outage depends on the temperature, not on guesses. A thermometer in each compartment shows whether food stayed at or below 40°F.
What to look for: digital or dial, readable without opening the door, battery or no battery
See options on AmazonNice to have
Portable power station
$150–$500Runs the router, a hub, lights and chargers for a day or more, and can keep a small refrigerator going for a while if its rating allows. It is the step up from a router UPS.
What to look for: at least 250 Wh for a router, 500 Wh or more for lights and fridge, pass-through charging, an outlet rating above your load, recognized safety certification
See options on AmazonCellular hotspot or router for failover
$50–$200Lets the router’s internet continue when your cable or fiber line fails but the cell network is up.
What to look for: a data plan you can use for home equipment, battery operation, a SIM slot or a plan that allows tethering, external antenna ports if signal is weak
See options on AmazonBattery or hand-crank weather radio
$20–$60Keeps you informed when mobile networks are congested or down.
What to look for: NOAA weather bands, hand-crank or solar charging, USB output, alert function
See options on AmazonStep by step
- Measure or look up the wattage of your modem, router and hub, then use the runtime calculator to find the battery size you need for 4 to 8 hours.
- Plug the modem, router and hub into the UPS, and leave other devices on the wall. Label the UPS plug.
- Pull the plug on the wall for 10 minutes while you watch your phone: check that Wi-Fi stays on, that the hub reports and that alerts arrive.
- Put lanterns, power banks and the weather radio in one box where everyone can find it, and charge them every three months.
- Place a thermometer in the refrigerator and in the freezer.
- Install CO alarms outside bedrooms and on each level, and test every alarm.
- Write a short plan: where the main breaker is, who calls the utility, where the lanterns are and what to do for anyone with medical equipment.
Cheaper or upgraded versions
Budget version, about $70–$130: a router UPS, one lantern, one power bank and two thermometers. It keeps you online for a few hours and lets you check food safety.
Upgrade, about $400–$900: a 500 Wh or larger power station, a cellular failover router, the six essentials and a transfer switch installed by a licensed electrician if you own a generator.
Frequently asked questions
Will a UPS keep my smart home working during a power outage?
It keeps whatever is plugged into it: usually the modem, router and hub. Wi-Fi sensors and battery devices can keep reporting while your internet provider is up. Lights, plugs and speakers on the wall stay off.
How big a battery do I need for a router?
Divide your load in watts into the battery’s usable watt-hours. A 22 W load runs about 3 hours on a 100 Wh desktop UPS and 7 to 8 hours on a 250 Wh power station. The calculator on this site does the math.
Can I run a generator in the garage?
No. Generators must run outdoors, at least 20 feet from windows, doors and other openings, with the exhaust pointing away from the house. Never run one in a garage, even with the door open.
Do smart locks still work during an outage?
Battery-powered locks keep working, and they keep a physical key as a backup. Remote access and alerts need the hub and internet, so put those on battery backup too.
Sources
- FEMA / Ready.gov — Be Prepared for a Power Outage (hazard information sheet, Dec. 2023)
- U.S. Consumer Product Safety Commission — Carbon Monoxide Information Center
- FoodSafety.gov — Food safety during a power outage
- U.S. HHS — emPOWER Program
- New York State DHSES — Lithium-ion battery consumer safety guide
- U.S. Fire Administration — Smoke alarms