Flagship phones have reached a point where they can be considered 'fast enough', and we're no longer yearning for that extra bit of speed. But the more capable phones become the more we rely on them, and the less likely they are to keep up with our digital lives.
Battery life has thus become the new benchmark for phone performance. But if a phone doesn't offer what you need out the box or its battery degrades over time, a power bank can help you get what you need.
Confusingly for consumers, not all power banks are created equal. We'll help you to wade through this mess to find the best power bank for your precise needs. Also, check out our roundup of the best solar chargers.
What's the best power bank you can buy?
1. Zendure A2
- RRP: £29.99
It might seem strange to find a power bank at number one in our chart that doesn't have an LCD screen, doesn't support USB-C or Lightning, doesn't have multiple outputs and doesn't feature Quick Charge 3.0 support. But we stand by our claim that the Zendure A2 is absolutely the best personal power bank on the market. It's compact. It's good-looking. It's fast. It's super-tough. It's plug-and-go. It has enough capacity for several charges and it's great value. A well worthy winner of our best power bank crown.
2. Anker PowerCore Speed 10000 QC
- RRP: $35.99
Fast, portable, high in capacity and affordable. There are some boxes the Anker PowerCore Speed 10000 QC power bank does not tick, yet you’d be pushed to find fault with it at £25. A recommended gadget for the upcoming festival- and holiday season.
3. RavPower PowerStation Series 20100mAh Portable Power Outlet
- RRP: $99.99
It has a similar usable capacity to the similarly priced Omnicharge, yet lacks its LCD screen and is much larger and less easily portable. However, this RavPower PowerStation Series 20,100mAh Portable Power Outlet is much easier to get hold of in the UK and even comes with a UK three-pin AC outlet. Both devices are expensive at around £100, but offer insanely fast charging (and recharging) of almost anything you like. A fantastic buy if you can afford it.
4. Dodocool 20100mAh Power Bank with 45W USB-C PD
- RRP: $65.99
A 45W USB-C power bank that can charge laptops as well as phones and tablets, and all at the same time. Functional in design - and looks - this Dodocool power bank comes at a good price.
5. Anker PowerCore Speed 20000 PD
- RRP: $79.99 (with 30W PD wall charger)
The PowerCore Speed 20000 PD is a good-value, high-capacity power bank that offers insanely fast charging and recharging speeds, and hails from one of the best-known brands in power-bank tech. Don't make the mistake of assuming its 22.5W USB Power Delivery port will charge any USB-C laptop, however.
6. Anker PowerCore II 10,000 Slim
- RRP: $37.99
The Anker PowerCore II Slim comes at a good price and has a useful amount of capacity for keeping your phone or tablet topped up away from home. The Quick Charge 3.0 support and fast recharging is very welcome but only for phones that support it, and the design is reasonably attractive as far as black plastic power banks go.
7. Zendure A3
- RRP: US$37.89
Higher in capacity than the class-leading Zendure A2, but with the same indestructable design and an extra USB output, the Zendure A3 is a great choice if you want a little more pocketable power for charging your phone and/or tablet away from home. If you need more power still check out the £40 Zendure A4, which is otherwise identical to this Zendure A3.
8. DXPower Armor DX0001
- RRP: US$19.99
A good-looking, mid-capacity rugged power bank that will fit neatly into the pockets of campers, hikers and other outdoorsie-types. It's a shame that the DXPower Armor is waterproof only when it's not in use, but this is a criticism we could level at most - if not all - 'waterproof' power banks.
9. Flux Card
- RRP: US$25
- Buy from Flux Chargers
A fantastic upgrade over the original Flux Charger, the new 4,000mAh Flux takes onboard all our criticisms and comes back fighting. An excellent, truly portable power bank that will get any smartphone user out of a jam. If you need more capacity, also see the 10,000mAh Flux Charger Plus, now with two additional full-size USB outputs.
10. CHJGD Magnum Opus Mini
- RRP: $24.99
A smaller version of the recommended Magnum Opus, the Opus Mini is a better fit for your pocket and for your wallet. The LCD screen is a very useful inclusion.Our only real criticism concerns the lack of passthrough charging.
How to choose the best power bank for you
Power banks come in three sizes: small lipstick-style devices that might charge your phone once and cost about a tenner; compact units with a mAh rating of between 5,000- and 10,000mAh that will offer two- or three full charges and might cost around £20; and high-capacity devices that will keep you going for days on end away from mains power and that will set you back anywhere between £25 and £100.
If you're wanting to take a power bank on a plane, know that the maximum capacity you can take in hand luggage is 100W, or around 27,000mAh.
Whatever its stated capacity, remember that not all of that juice is available for charging. The typical energy efficiency is between 60- and 70 percent, but some go as high as 90 percent - where this is the case it will be mentioned in the product specs. If it's not stated, assume around 60 percent efficiency rating and consider anything on top of that a bonus.
We test lots of power banks, and in this group test have given examples of some of our favourites, but there are so many available on the market and from so many different vendors that you're better off going into this knowing what features you want to look for and then choosing accordingly.
Do you need multiple outputs? Do you want a USB-C or Lightning input/output, or an AC outlet? (The latter are significantly more expensive.)
Would you benefit from passthrough charging (also known as charge-through technology)? This allows you to simultaneously charge the power bank and a connected device, thereby freeing up power outlets in your home.
Do you want an LCD screen that can give you an exact read-out of what capacity remains or are you happy with LEDs?
Do you need a rugged or waterproof casing? And if you're going away from civilisation would you benefit from a built-in LED flashlight and a built-in solar panel?
You might think living in the UK our grey climate would rule out the use of such a device, but even in cloudy conditions these devices can draw some solar power.
Power banks and charging speed
One of the most confusing things for many people when it comes to working out which power bank they should buy is figuring out how fast it is, or rather how fast it should be.
If it's a small device that will fit in your pocket along with your phone then you might not be so worried about how fast it can recharge your handset, but speed is particularly important when you want to charge a laptop or tablet, which may refuse to charge from slower outputs.
Confusingly, the term 'fast-charging' is thrown around a lot within marketing, and it doesn't really mean anything. The minimum you'll see is 5W, and we would not recommend this. Although some phones are still sold with 5W chargers, most devices will accept more than this.
In our view anything below 10W should be considered standard (read slow), and anything above 10W fast. Then you also have various Quick Charge standards - all of which are backward-compatible - which will get you up to 18W, but only on compatible devices.
If it's a high-capacity power bank then you should look for 'fast-charging' inputs as well as outputs. Do bear in mind, though, that in order to refill a power bank at 18W you will need a mains adaptor that is capable of delivering 18W to it.
Increasingly power banks feature clever technology called PowerIQ or similar. This allows the bank to recognise the type of device you have connected and deliver the optimum amount of power.
The input rating is key when it comes to recharging the bank - the higher is this figure the more quickly it will charge. You'll see a figure in Amps, and you multiply this number by the voltage (5V for USB) to find the rating in Watts.
You can use any output to charge any USB device - it will draw only the power it needs.
If a power bank has several outputs the maximum total output capacity is key, since it may not be able to simultaneously support each at full power.