How Long Will a Power Station Run a TV and WiFi Router?

Watt-hour math for a TV, modem and router on a power station. Low loads add up, so learn how to estimate hours and save power.

A TV and internet gear are small loads, but they are the loads people want most during a long outage: news, weather updates, a way to work or keep kids occupied. They run happily on a modest battery if you do the math.

Here is how to estimate runtime for a television, a modem and a router, and how to get more hours out of the same battery.

Know the watts

Find the rated watts on each device's label or in the manual, or measure with a plug-in meter. Ranges differ a lot between models.

• Modem and router: each uses a small, steady amount. They run all the time, so the hours add up. A single combined unit uses less than two.
• LED television: draw depends on screen size and brightness. Larger screens use more. Older plasma and some older sets use much more than modern LED screens.
• Streaming stick or set-top box: small, but add it to the total.
• Laptop: usually modest compared with a TV.

The runtime formula

Total the watts of everything running together. Multiply battery watt-hours by 0.85 to allow for inverter losses, then divide by the total watts. The answer is hours.

Example: a 500 Wh battery, a modem and router together using about 20 W, and a TV using about 60 W. Total 80 W. 500 x 0.85 = 425 Wh. 425 / 80 is roughly 5 hours.

Run the router alone and the same battery lasts about 21 hours at 20 W. The TV is the biggest cost.

Sample runtimes

These are illustrations. Use your own wattage.

• 300 Wh battery, router and modem only (20 W): about 12 hours.
• 300 Wh battery, router, modem and TV (80 W): about 3 hours.
• 500 Wh battery, router, modem and TV (80 W): about 5 hours.
• 1000 Wh battery, router, modem and TV (80 W): about 10 hours.
• 1000 Wh battery, router and modem only (20 W): about 42 hours.

Get more hours

1. Use the TV in short blocks for news or weather, not as background noise.
2. Lower the brightness. Many TVs have an energy saving mode.
3. Turn the router off at night if nobody needs it, or only when the household is asleep.
4. Watch on a phone or tablet instead of the TV. A phone uses a tiny fraction of the power.
5. Use a battery radio for news instead of the TV. See best emergency radios.

Plug in smartly

• Use a power strip with a switch so you can turn off several devices at once, but do not exceed its rating.
• Some devices draw power even when "off". Unplug or switch off at the strip.
• Do not overload the station. Total running watts must stay below its continuous rating.
• Keep the station in a dry spot with airflow around it.

Priorities during an outage

Entertainment is not the first thing a battery should power. Fridge and freezer, medical equipment, heating fans and phone charging come first. Use the leftover capacity for the TV. Our guide on what to plug into a power station first gives a ranking. To compare sizes, visit our power station hub.

Measure once, then trust the math

The easiest way to get a dependable number is to plug the TV, modem and router into a plug-in watt meter for an evening and note the reading. Write the total on a sticky note and attach it to the power station. Next time the power fails, you can divide the battery's remaining watt-hours by that figure and know the hours left in seconds. Many power stations also show live watts on their screen, which does the same job without a meter. Check it against your estimate and adjust.

Remember that a battery that is not full gives less runtime. Top it up every few months so it is ready when needed, and replace aging gear that uses more power than it should.

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