Best Power Banks for Power Cuts: What to Buy in 2026
Quick answer: for most households, a 20,000mAh power bank is the sweet spot for a power cut. It is large enough to recharge a modern phone several times, but still small enough to keep charged and ready. If you also need to run a USB-C laptop, pay close attention to output wattage rather than capacity alone.
A power bank will not run your fridge or kettle, but it can solve one of the most immediate problems in an outage: keeping phones, small lights, radios and other USB-powered devices working. That makes it one of the cheapest preparedness purchases worth making.
Our current shortlist
High-output pick: Anker Prime Power Bank (20K, 220W)
Anker’s current UK Prime 20K model has a 20,100mAh rated capacity, up to 220W combined output and up to 140W from a single USB-C port. It can also accept up to 100W when recharging. That combination makes it unusually capable for a portable battery: it is suitable not only for phones, but also many USB-C laptops and tablets.
For preparedness, the useful feature is not the headline 220W figure by itself. It is the ability to keep several devices charged quickly when mains power is unavailable, followed by relatively fast recharging when electricity returns.
Lower-cost approach: a 20K bank around 30–90W
If you only care about phones, a premium 140W laptop-capable power bank is unnecessary. Anker’s current UK range also includes simpler 20,000mAh models with lower USB-C output. These cost substantially less and are more than adequate for phones, small lights and many tablets.
Capacity: why 20,000mAh is a sensible target
Power-bank capacity is usually advertised in milliamp-hours (mAh), but you should not expect every advertised unit of energy to reach your phone. Conversion losses, voltage conversion, cable losses and the battery management system all reduce usable output.
As a rule of thumb, think in terms of several phone charges, not an exact mathematical number. A 10,000mAh bank can be a useful everyday carry option; a 20,000mAh bank gives a household more breathing room during a longer outage.
USB-C output matters
Two power banks can both say “20,000mAh” and behave very differently. A 30W USB-C model is excellent for phones and tablets. A 100W+ model can support many laptops. If your goal is keeping a work laptop alive, check the laptop’s charger wattage and the power bank’s maximum single-port USB-C output.
Features worth paying for
- USB-C Power Delivery: the most useful modern charging standard for phones, tablets and many laptops.
- A clear battery percentage display: much more useful during an outage than four vague LEDs.
- Fast input charging: when power returns briefly, a bank that recharges quickly is easier to keep ready.
- Multiple outputs: useful for households with several phones.
- Reputable battery protections: buy lithium batteries from established manufacturers and retailers.
What we would skip
Do not pay a large premium for gimmicks you are unlikely to use. Tiny built-in solar panels on a power bank are generally too small to be the main way you recharge it. A built-in torch can be convenient, but a separate rechargeable torch is usually better as your main source of light.
How many power banks should a household own?
A sensible arrangement is one larger bank kept at home and smaller everyday banks that household members already use. The bigger preparedness win is remembering to keep them charged. Set a recurring reminder to check stored power banks every few months.
Our buying rule
If you only need phones: prioritise capacity and reliability. If you need laptops: prioritise single-port USB-C wattage as well. If you need appliances: stop looking at power banks and move up to a portable power station.
A compact 10,000mAh option to consider
Anker Power Bank, 10,000mAh 30W with USB-C Travel Essential Portable Charger is a compact option worth comparing if you want something lighter than a 20,000mAh power bank while still getting USB-C charging and a useful emergency reserve.
View the Anker 10,000mAh 30W Power Bank on Amazon (paid link)
Buying note: check the current product specification, ports and watt-hour rating on the listing before ordering, as Amazon listings and model details can change.
Sources and specifications
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