Battery Backup for a Router and Modem: How Long Can You Stay Online?

The power goes out and within ten minutes somebody asks whether the wifi is still working.

It isn't, because the router is dead. And the phones are burning through data and battery while everyone refreshes the outage map.

Good news: this is the cheapest problem in backup power to solve. Bad news: solving it doesn't always work, and it's worth knowing why before you spend.

The numbers are absurdly friendly

A typical home router and cable modem together draw around 20 watts. verify

That's about a quarter of what one old-fashioned light bulb used.

Even the smallest unit here runs your internet for most of a day. A 1,000Wh station runs it for the better part of two days while doing plenty of other work at the same time.

There is genuinely no cheaper win in this whole category.

The catch nobody mentions

Your router being powered does not mean your internet works.

Between your house and the internet there's a chain of equipment: a node in your neighborhood, a cabinet down the street, equipment at the ISP's facility. All of it needs power.

Cable and fiber providers do run battery backup at those points. It's finite — commonly a few hours, not a few days. verify

So in a short outage, powering your router genuinely keeps you online. In a two-day regional event, your router hums along happily connected to nothing.

The alternative most people should consider

A phone hotspot.

Cell towers generally have their own backup power and often stay up longer than home internet infrastructure does. A phone plus a decent power bank gets you online for a fraction of the cost and effort.

For a short outage, that's frequently the better answer — especially if all you need is to check on family and look at the outage map.

Keep the home router plan for longer events and for anything that genuinely needs a real connection: remote work, security cameras, a medical device that phones home.

The trick that stretches it further

Most routers and modems run on 12V DC. Your power station stores DC.

Plug into the AC outlet and the station converts DC to AC, then your router's brick converts it straight back to DC. You lose energy at both ends for nothing.

Use the station's 12V DC port instead, with the right barrel connector, and you'll get noticeably more hours out of the same battery. verify

Check the voltage and polarity on your router's power brick before you do this. Getting it wrong kills the router.

UPS or power station?

Both work. They're for different problems.

A small UPS is cheaper, switches over in milliseconds so your connection never drops, and it's designed for exactly this. If the router is genuinely the only thing you care about, buy the UPS.

A power station holds far more energy, runs your fridge too, and goes camping. Its switchover is usually fast enough that a router doesn't notice, but check the spec if you care.

Most people should own the power station and use it for everything, rather than buying a device that does one job.

What we would not buy

A big power station just for the router. You'd be spending several hundred dollars on a 20-watt problem. Buy the small one, or the UPS.

A cheap unbranded UPS with a sealed lead-acid battery. They die quietly after two or three years and you find out during the outage. Check the battery is replaceable.

Straight answer

Whatever power station you already bought for the fridge will run your internet almost as an afterthought. Plug it in and forget it.

If you're buying specifically for this, the smallest LiFePO4 unit you can find covers it — and honestly, test how long your ISP stays up first. That number decides whether this is worth solving at all.