The short answer
Once your landline moves to digital, the phone only works in a power cut if the router does, and providers only have to guarantee one hour of backup. A mini UPS that plugs between the router and its power adapter buys more. Ranked by what each hour of backup costs at a 10W load, the TalentCell 99.9Wh is cheapest at £7.51 an hour of backup, but its 12V outputs drift between 9V and 12.6V as it drains. The Yuuki Power 53Wh is close behind at £8.38 and gives a steady 12V at 1.5A, the rating of BT's Smart Hub 2 adapter. If you have full fibre and need to power the fibre box too, the Wbacon 75Wh has five 12V outputs.
Most listings make this hard to check. Of the 15 we read, only 5 state the battery in watt-hours, the one unit that tells you how long it lasts.
This guide is for anyone moving to a digital landline, or anyone who wants Wi-Fi to survive a power cut. It ranks mini uninterruptible power supplies (UPS) by the cost of each hour of backup they give a typical router. It is desk research: we read the listings and the makers' pages and did the arithmetic. We have not tested these units. For the background on the switchover itself, see our digital landline switchover guide.
Prices and specs last checked by Look Into on 28 October 2026 · next check 23 December 2026 · how we picked
Why a router needs a battery now
An analogue phone line carries its own power, so a basic corded phone kept working in a power cut. A digital line does not. GOV.UK says handsets and routers on a digital line need your home supply and will not work in a power cut without a battery (GOV.UK). Providers must offer at least one hour of emergency access, free for customers at risk (Ofcom). If you qualify, ask your provider for its battery backup unit before you buy anything. EE lists its own Battery Back Up Plus at £149.99, and it was out of stock when we checked on 28 October 2026 (EE).
Step one: what your router draws
Backup time is battery energy divided by the load. Three published figures frame the load:
- 18W is a ceiling. BT's Smart Hub 2 power adapter is rated 12V at 1.5A, which is 18W (BT). An adapter rating is what a device may draw, not what it does.
- About 6W is a floor for a hub alone. The EU Code of Conduct on broadband equipment allows a home gateway 2.3W to 3.0W idle plus roughly 1.7W to 1.8W per Wi-Fi 6 radio. A dual-band hub with two radios comes to 5.7W to 6.6W. Our Always-On Load Index sets out those allowances.
- A full fibre box adds its own draw, and Openreach does not publish one we could find. Read the volts and amps on its adapter label.
We use 10W as the worked example in the rankings: a hub between its idle allowance and its adapter ceiling. If you want your own figure, a smart plug with energy monitoring will measure it. Then:
Hours of backup = battery watt-hours (Wh) ÷ load in watts. A 53Wh battery at 10W gives 53 ÷ 10 = 5.3 hours. Treat that as an upper limit, because none of these makers publishes how much energy is lost converting the battery voltage to 12V.
Cost per hour of backup = price ÷ hours at 10W, using the Amazon UK price we read on 28 October 2026. Lower is better. This is what we rank on, because a bigger battery is only better value if each hour costs less.
What we found when we read 15 listings
On 28 October 2026 we read every unsponsored, in-stock result on the first page of amazon.co.uk for "mini ups for router": 15 listings, each one's title, bullet points, description and specification table.
- 5 of 15 state the battery in watt-hours.
- 8 of 15 give only a milliamp-hour figure, and none of those 8 states the voltage it was measured at. Without the voltage, mAh cannot be turned into energy, so you cannot work out a backup time from the listing.
- The 2 big brands, APC and Eaton, state neither on their listings, and their own spec pages did not give a capacity either.
- 7 listings make a backup-time claim, and only 1 says what load it means. SKE's listing says it "can typically power an 18W router for 2 hours". The others say things like "up to 4-8 hours" or "up to seven hours" without a wattage.
So the ranking below only includes units whose capacity can be worked out: the five that state watt-hours (one of them is in "One to skip" below), and SKE, whose own claim of 18W for 2 hours implies 36Wh. APC is included as the brand option, unranked, because its runtime cannot be checked.
How they compare
| Pick | Stated capacity | 12V outputs | Hours at 6W | Hours at 10W | Hours at 18W | Cost per hour of backup at 10W |
|---|---|---|---|---|---|---|
| TalentCell Mini UPS 99.9Wh | 99.9Wh (11.1V, 9,000mAh) | 4, at 9V to 12.6V | 16.7 | 10.0 | 5.6 | £7.51 |
| Yuuki Power Mini DC UPS 53Wh | 53Wh (16,000mAh) | 1, at 1.5A | 8.8 | 5.3 | 2.9 | £8.38 |
| Wbacon Mini UPS 75Wh | 75Wh (20,000mAh) | 5, rated up to 5.4A | 12.5 | 7.5 | 4.2 | £10.13 |
| Yuuki Power Mini DC UPS 56Wh | 56Wh (18,000mAh) | 1, at 2A | 9.3 | 5.6 | 3.1 | £12.50 |
| SKE Mini UPS 10400mAh | 36Wh, implied by its own claim of 18W for 2 hours | 2, at 2A each | 6.0 | 3.6 | 2.0 | £13.05 |
| APC Back-UPS Connect CP12036LI | Not published | 12V, 36W | Not calculable. APC says "up to 4 hours of runtime for an average router" | Not calculable | ||
Capacities and outputs as stated on each Amazon UK listing, read 28 October 2026. Hours are capacity divided by load, before conversion losses. Costs use the price read the same day; the live price is in the table below.
Prices in this table come from Amazon and are refreshed at least once a day, with the date of the last update under the table. The cost-per-use and running-cost figures on this page use prices Look Into read on 28 October 2026, so they can differ from today's price.
As an Amazon Associate, Look Into earns from qualifying purchases. Product prices and availability are accurate as of 28 October 2026 and are subject to change.
The picks
TalentCell Mini UPS 99.9Wh
Price: check the live price on Amazon · £7.51 per hour of backup at 10W · 10.0 hours at 10W
The biggest battery in the set and the cheapest per hour. It is also the only listing whose capacity can be checked from first principles: it states 11.1V and 9,000mAh, and 11.1 × 9 = 99.9Wh. It has four 12V DC outputs, which covers a hub and a fibre box with room to spare, plus USB-A and USB-C for a phone.
The catch: the listing gives the 12V outputs as "9-12.6V". That is the battery's own voltage passed straight through, so it falls as the battery drains. A router built for a steady 12V may switch off before the battery is empty, and we could not find out at what point that happens for any given hub. The barrel plug is 5.5mm by 2.1mm, so check your router's socket.
Best for: the longest backup for the money, if your router tolerates a falling voltage.
Check price on Amazon →Yuuki Power Mini DC UPS 53Wh
Price: check the live price on Amazon · £8.38 per hour of backup at 10W · 5.3 hours at 10W
A regulated 12V output at 1.5A, which is exactly the rating of BT's Smart Hub 2 adapter, so for that hub the numbers line up without guesswork. It also has 9V and 5V outputs and a USB port, and the listing names the BT Smart Hub as its target.
The catch: only one 12V output, and a total limit of 18W across all ports. If your fibre box also needs 12V, this will not run both. There is no headroom either: a hub that draws its full adapter rating would take the whole 1.5A.
Best for: a single hub on a part-fibre (FTTC) line, or a Smart Hub 2 where the fibre box can stay unpowered.
Check price on Amazon →Wbacon Mini UPS 75Wh
Price: check the live price on Amazon · £10.13 per hour of backup at 10W · 7.5 hours at 10W
Five DC outputs rated at up to 12V and 5.4A, plus USB-A, USB-C and a PD port, in a unit the listing rates at 65W. That is enough to run a hub and a fibre box together. The listing states 20,000mAh and 75Wh, and claims "up to seven hours". Seven hours from 75Wh implies an average load of about 10.7W, which is in line with our 10W example rather than an exaggeration.
The catch: the dearest pick in pounds, and a 65W rating is far more than a router needs, so part of what you pay for is capacity you will not use for this job.
Best for: full fibre homes that need the router and the fibre box kept up together.
Check price on Amazon →Yuuki Power Mini DC UPS 56Wh
Price: check the live price on Amazon · £12.50 per hour of backup at 10W · 5.6 hours at 10W
The bigger sibling of the 53Wh unit: 12V at 2A rather than 1.5A, and 24W in total rather than 18W. That headroom matters if your hub's adapter is rated above 1.5A.
The catch: 3Wh more battery than the 53Wh model for noticeably more money, so each hour of backup costs half as much again. Still one 12V output.
Best for: a single router whose adapter is rated 12V at up to 2A.
Check price on Amazon →SKE Mini UPS 10400mAh
Price: check the live price on Amazon · £13.05 per hour of backup at 10W · 3.6 hours at 10W
The one listing of the 15 that says what its backup time means: it "can typically power an 18W router for 2 hours". That works out at 36Wh delivered, which is where our figures come from. It has two regulated 12V outputs at 2A each, so it can run a hub and a fibre box.
The catch: the smallest battery here, so the shortest backup, and the dearest per hour of the picks.
Best for: a hub plus fibre box where a couple of hours is enough.
Check price on Amazon →APC Back-UPS Connect CP12036LI
Price: check the live price on Amazon · cost per hour not calculable
APC is the best-known UPS maker, and this is its 12V lithium-ion unit for routers, rated 36W, with two extra pairs of DC tips. Schneider Electric, which owns APC, says it gives "up to 4 hours of runtime for an average router" (Schneider Electric).
The catch: neither the listing nor the maker's page states the battery capacity, and "an average router" is not a wattage. We cannot rank it, and you cannot check the four hours.
Best for: buyers who want a known brand's support and warranty over a checkable number.
Check price on Amazon →One to skip
The Yuuki Power Mini DC UPS 32Wh works out at £17.36 per hour of backup at 10W, more than any pick above. It also cost more than the same maker's 53Wh model on the day we checked, for 21Wh less battery. Buy the 53Wh version instead.
Before you buy: five checks
- Read your router adapter's label. Note the volts (almost always 12V) and the amps. The UPS output must match the volts and meet or beat the amps.
- Count what needs power. A full fibre line has a separate fibre box with its own adapter. If you want the phone to work, both need backup.
- Check the plug. Most of these use a 5.5mm by 2.1mm barrel. Some include adapter tips; make sure one fits.
- Prefer a listing that states watt-hours. If it only gives mAh with no voltage, you cannot work out the backup time.
- Ask your provider first. If you rely on your landline, you may qualify for a free battery backup unit or hybrid phone.
The questions that come up most
How long will my router last on a mini UPS? Divide the battery's watt-hours by your router's watts. A 53Wh unit on a 10W load gives about 5.3 hours at most.
Will a power bank do the same job? Only if it has a 12V output and can charge and supply power at the same time. Most phone power banks give 5V USB, which a router cannot use without a step-up cable, and they do not switch over automatically.
Is a normal plug-in UPS better? A mains UPS turns battery power back into 230V for the router's own adapter to turn back into 12V, losing energy twice. A 12V DC unit skips both steps. For a bigger backup, a portable power station can run a router for a day or more.
Will my phone work during the switch to battery? These units are sold as uninterruptible, but none of the listings we read publishes a switchover time. If the router reboots, a call in progress will drop.
How Look Into made this guide
Desk research, not a hands-on test. On 28 October 2026 we read the 15 unsponsored, in-stock Amazon UK results for "mini ups for router" and the makers' pages for APC and Eaton. Capacities, outputs and claims are quoted from those pages. Backup hours are capacity divided by load, at 6W, 10W and 18W, the last two explained above. Cost per hour of backup is the Amazon UK price read that day divided by hours at 10W. Rankings are by that figure and nothing else. Look Into earns a commission on Amazon purchases; it does not affect the order.
Sources
- Amazon UK listings for B08FBB4Q8V, B0FCS7MP8L, B0FP9DF4N1, B0FCSWRB59, B0CNT6LLHP, B0CJ5D89Z9 and B0FCV2Q8TB, and the first results page for "mini ups for router", read 28 October 2026
- BT, Smart Hub 2 power efficiency information, read 28 October 2026
- Schneider Electric, APC Back-UPS Connect CP12036LI, read 28 October 2026
- Eaton, 3S Mini 3SM36B datasheet (as hosted by a reseller), read 28 October 2026
- EE, Battery Back Up Plus (Digital Voice), read 28 October 2026
- GOV.UK, UK transition from analogue to digital landlines; Ofcom, Protecting customers during the migration to digital landlines
- EU Code of Conduct allowances for home gateways, as set out in our Always-On Load Index
Changes to this page
- 28 October 2026: page published.