Best battery backup for your wifi router (UK 2026)
Your broadband survives most power cuts — it’s the router in your house that goes dark. A small battery fixes that for a day or more of runtime. Here’s the maths, the setup that makes the wifi never even blink, and the three units we’d use.
What your broadband actually needs
A typical UK router draws 8–15W. A full-fibre ONT adds 5–10W. Call it 20W worst case for the whole broadband stack — which means even a small battery keeps you online for hours:
| Battery size | Router + ONT (~20W) | + laptop & phone charging |
|---|---|---|
| 256Wh | ~11 hours | ~4 hours |
| 512Wh | ~23 hours | ~9 hours |
| 572Wh | ~26 hours | ~10 hours |
| 768Wh | ~34 hours | ~14 hours |
And yes — your broadband usually stays up in a power cut: the street cabinet and exchange have their own battery backup. The weak link is the router in your house. (Full explanation in our keep-wifi guide.)
The best router backup options
EcoFlow RIVER 3 Max
Enough battery to ride out even a long rural outage with the router, phone charging and a lamp running, small enough to live under the desk, and its 10ms switchover UPS mode means you can leave the router plugged through it permanently — when the power drops, the wifi doesn’t even blink.
That pass-through UPS trick is the reason we recommend a small power station over a traditional computer UPS: you get the same always-on protection, plus a battery you can take camping, and no lead-acid battery to replace every three years.
EcoFlow RIVER 2 Pro
The extra 200Wh and 800W output turn a router-backup unit into whole-outage cover: broadband, fridge top-ups, the kettle via X-Boost. If a power cut means working from home must continue, this is the sensible size.
Jackery Explorer 500 v2
Lighter and slightly smaller than the RIVER 3 Max with nearly the same runtime. It lacks the instant UPS switchover, so it’s best kept charged on standby rather than inline — a 30-second swap when the lights go out.
Setting it up so the wifi never drops
1. Plug the router (and ONT if you have full fibre) into the power station’s AC sockets, and the power station into the wall. Units with UPS/pass-through mode (like the RIVER 3 Max) run mains through to the router while keeping the battery full.
2. Label the sockets — in a real outage at night you don’t want anyone unplugging the router to charge a phone. Use the USB ports for phones instead.
3. Test it: flip the socket switch off and check the wifi stays up. Do this once a season.
4. Keep 20–30% battery as a floor. Router-only draw is tiny, but the temptation to run the TV off it during a long cut is real.
Pair it with our power cut checklist and a quick check of who your DNO is and a winter outage becomes an inconvenience instead of a lost workday.
Frequently asked questions
Does broadband keep working in a power cut?
Usually yes. Full-fibre and cable networks have battery backup at the street cabinet and exchange — the equipment that dies is the router and ONT in your home. Power those two and you're back online. Copper landline phones are being retired, so battery-backing the router matters more each year.
Can I use a normal computer UPS for my router instead?
You can, but a small LiFePO4 power station is better value for UK homes: 5–10x the battery capacity, no lead-acid replacement every few years, silent, and usable for camping or other outages. A traditional UPS only wins if you need to protect a desktop PC from instant cuts too.
How long will a power station run a wifi router?
Router plus full-fibre ONT draw about 15–20W combined, so a 572Wh unit runs them for roughly 24–26 hours, and a 768Wh unit for around 34 hours — longer than the vast majority of UK power cuts, which are measured in minutes to hours.
Should I leave the router permanently plugged into the power station?
If the unit has UPS/pass-through mode with fast switchover (the RIVER 3 Max does), yes — that's the whole point: mains passes through, the battery stays full, and an outage never interrupts the wifi. Units without that mode are better kept on standby and swapped in when needed.
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