For years now friends, family and even colleagues have wondered how I am able to spend so long playing around with power banks. They just charge your phone, right, so what's the big deal? Well...
Not all power banks are created equal. You've got cheap ones and pricey ones as in all veins of consumer tech, and as with anything else sometimes you're just paying for a name. But beyond that, there's so much more to portable power than a charging brick with a USB output.
We want the fastest charging speeds - for the bank itself and for the phone - and to know at a glance that a portable charger is going to get us through the day with juice to spare, even share. But we don't want it weighing down our pockets.
We want multiple ports for charging additional gadgets, and more efficient use of power outlets to free up sockets. We don't want to carry multiple charging cables - in fact we don't want to carry any cables at all.
Design and capacity are most important, sure, but what about wireless- or even solar charging? What about an LCD screen? Waterproofing? Don't you want the coolest and most convenient power bank you can get for your money without paying over the odds?
What capacity power bank do I need?
Power bank capacity is commonly misunderstood. You don't need to understand what is mAh, only that if your phone spec says it has a 4,000mAh battery you are going to need at least a 4,000mAh power bank in order to get a full charge.
Actually you need more than that. No power bank runs at 100% efficiency, with most averaging around 65%, and some hitting as high as 80- or 90%. The latter are the ones you want.
In order to fully charge a 4,000mAh battery phone, you're likely going to need something more like a 6,000mAh power bank. So all those 5,000mAh banks that claim to charge your phone twice, don't believe a word - not unless you've got a really old phone with a tiny battery.
Power banks tend to sold in 5,000mAh, 10,000mAh and 20,000mAh capacities, with a few variations in between. As a rule of thumb, 5,000mAh is a single-use power bank that will be easily portable; 10,000mAh hits the sweet spot, both portable and offering at least two full charges; 20,000mAh is high-capacity, most useful for those who are going to be away from mains power for extended periods or will be charging multiple gadgets. Don't attempt to stuff a 20,000mAh power bank in your pocket.
Of course you can buy power banks with significantly higher capacities, which are particularly useful if you want to charge a laptop (see our round-up of PD power banks for that), but they are going to be much bigger, bulkier and more expensive.
Do note that if you're travelling on a plane your power bank must be in your hand luggage, and anything over 27,000mAh (100Wh) needs approval from the airline (over 43,000mAh/160Wh, forget it).
With great power comes two great problems, however. First, recharging the power bank can take forever (okay, like nearly a day in some cases). Second, with most power banks offering a row of four LEDs to denote how much power remains inside the bank, working out how much you've actually got left can be impossible.
Solutions here are simple. An LCD screen will give you an exact readout of remaining capacity, though these are rarely found on low-capacity and cheap banks. Passthrough charging lets you charge both the power bank and connected devices at once, freeing up power sockets if you are going to have to leave it plugged in for long periods. Ensuring you have the fastest possible input (typically a USB-C PD input, which can be as high as 100W) will also speed things up.
What speed power bank do I need?
If I had it my way 5W power banks would be banned. They are painfully slow. Anything lower than 10W: nope.
These days even 10W, though marketed as 'fast charging', barely scratches the surface of what recent smartphones are capable of. With some able to go as high as 45W over a wired connection, a 10W power bank is not going to feel especially convenient.
That said, 10W is more common among the budget- and mid-range, and many people will be using 10W chargers at home. But we'd still recommend looking for a faster power bank, especially those with Quick Charge or Power Delivery support (even if your current phone doesn't support it, a later upgrade most likely will).
That seems pretty straightforward, although power manufacturers rarely provide the speed of their outputs measured in Watts. Instead you'll see a rating in Amps, which you multiply by five (the Voltage rating) to get the rating in Watts. So 2A x 5V = 10W.
Which outputs do I need?
If you're an iPhone user (and intend to stay an iPhone user), look for a power bank with a Lightning port that can serve as input and output to save you scratching around for cables you wouldn't otherwise use.
Android phones are increasingly moving over from Micro-USB to USB-C, and in which case a USB-C port that acts as input and output is preferable. However, it's still common for power banks to be recharged over Micro-USB, and sometimes you'll find both Micro-USB and USB-C. Don't try to use them simultaneously for recharging the bank. As a rule of thumb, USB-C is going to be the faster option.
How many ports you need depends on how many gadgets you want to charge at once. If more than one, watch out for power banks with a max output that is lower than the sum of all ports together - they won't be able to deliver the maximum rated output of all at once. Also watch out for capacities that are too low to fully charge multiple devices.
There is no need to worry about plugging devices into ports that are capable of delivering more power than they are able to accept, since USB devices will draw only the power they need. Many power banks include technology that is able to intelligently dole out this power among ports more appropriately depending on what devices you are attempting to charge (often known as Power IQ or similar).
Wireless power banks are becoming more commonplace, and here you won't need any outputs if you're intending to use it only for wireless charging. An input will still be required to recharge the bank itself.
We've put together a range of articles to help you choose the best charging tech for the mobile devices you carry everywhere. You'll also like:
- For charging away from home: Power banks for phones & tablets | Power banks for laptops | Travel adaptors
- Best Wall & Desktop Chargers: For phones & tablets | For laptops
- For convenience: Best wireless chargers
- Best charging cables: Micro-USB | USB-C | Lightning
1. Zendure Power Banks
Zendure is a long-time Tech Advisor favourite, with a range of devices starting with the 6,700mAh A2 and culminating in the 26,800mAh A8. Key differences in the range are focused on price, capacity and number of ports, and Zendure is in the process of updating the line with USB-C and Power Delivery.
The A2 stands out to us as the best all-rounder, with an affordable price, a usable capacity and a compact design. The tech inside is also very good, with super-efficient batteries that can retain 95% of their charge after six months and deliver a higher-than-average 80% of their capacity to your phone. There's passthrough charging, too, so you can charge both the power bank and a connected device from a single power outlet.
The design is notable for its durability, with a cool-looking and virtually indestructible crushproof PC/ABS composite material with dual-injection moulding and a shock-absorbing central belt. Four LEDs denote its remaining capacity, though higher up the line in the A8 you'll find an LCD screen.
The basic A2 doesn't support Quick Charge or USB-C, though its 12W output is speedy. There's also a 10.5W Micro-USB input for recharging. Look to other Zendure models for these features, plus additional ports.
Read our full Zendure A2 review
2. Xiaomi Power Banks
We're a little torn between Zendure in first place and the Xiaomi range of power banks, which are not as easy to get hold of but they cannot be beaten on value and are equally well designed.
Though the Mi Power Bank 2 wins the prize for best value, the Pro is most interesting to us for its 18W USB-C port that acts as both input and output. There's also a full-size USB output, plus support for passthrough charging. (The 2 and 2S are Micro-USB banks.)
At this price you'd typically be looking at a basic-looking matte-black plastic bank with no bells and whistles. These are super-slim aluminium-alloy banks with a premium finish, and despite their reasonable capacities they are compact and feature rounded corners that make them comfortable in a pocket and in the hand.
Also interesting is their support for low-power charging, for devices such as fitness trackers - often when you attempt to charge a low-power device the bank will automatically turn itself off.
A larger 20,000mAh Mi Power Bank 3 Pro with an additional output and 45W Power Delivery is also available at Amazon.
3. Anker Power Banks
Anker is a very well-known brand in the power bank market, so you can buy with complete confidence. Its devices are a little more boring in terms of design, standard matte-black bricks, but the performance is all there and they offer great value.
Our favourite of all is the PowerCore Speed 10,000mAh QC, which has a super-compact design that will easily slip into a pocket. Anker claims it's 27 percent smaller than comparable banks at this capacity, and it weighs just 198g.
There's just a single input and single output, with four blue LEDs on top to show how much power remains. So it's nothing fancy, but the PowerCore Speed is functional and intuitive in use.
The Speed 10000 QC is an upgraded version of the PowerCore 10000, and you'll notice it has a blue plastic prong inside its full-size USB output to indicate the improved performance. It supports Quick Charge 3.0, Voltage Boost and PowerIQ, and these three performance technologies combined in essence ensure that any connected device is charged in the shortest amount of time possible.
If you don't have a Quick Charge-enabled phone you'll still get 12W from this output, and the input is also fast to refill the bank at 10W. Unfortunately there's no support for passthrough charging, which would have been the icing on the cake.
Also new with this version is a bundled mesh carry case, which is handy for keeping together the power bank and necessary cables.
Also recommended in the Anker line-up are the PowerCore II Slim, another 10,000mAh bank with a more rectangular body and faster 18W charging, and the 10,000mAh PowerCore Lite, which has an additional USB-C input.
Read our full Anker PowerCore Speed 10000 QC review
4. Tronsmart Power Banks
Arguably less well known in the UK, Tronsmart is another vendor of excellent value, high-performance and reliable power banks.
The Trim 10,000mAh is an interesting power bank, shipping with what appears to be a lanyard but actually unclips to reveal a cable that is Micro-USB at one end and a flat USB-A at the other, making it easy to refill the bank wherever you are. What's missing is a USB-C cable, which is necessary if you want to take advantage of its 18W Power Delivery port.
It's worth pointing out that the full-size USB port is also capable of delivering 18W to devices that support it, but the device's maximum output is 18W so neither will run at full-speed when the two are used together.
The Tronsmart Trim has a really nice design, rectangular but slim, at 144x70x12mm, and it weighs just 194g. The black casing has a matt finish that feels lovely in the hand (and not at all slippery), while a rose gold metal trim is seen around the edges.
For a higher-capacity model we like the Tronsmart PB20, a 20,000mAh bank with an LCD display, 15W fast charging, three USB ports and 88% conversion rate.
The Tronsmart is matte black but with a smooth texture, giving it a slick-looking design. Due to its capacity this battery is reasonably heavy (342g) and a little bulky at 137x68.5x26mm, so you may prefer to put it in a bag than slip it into your pocket. However, it weighs no more than is standard for other power banks of this capacity.
5. EasyAcc USB-C 10,000mAh Power Bank
The EasyAcc USB-C Power Bank is a slim 10,000mAh portable charger that boasts ports for both old-school USB-A and modern, reversible USB-C.
USB-C means faster output charging for mobiles and speedier input charging of the power bank itself.
At 5V/3A, it’s at the faster end of the power bank spectrum.
Its 10,000mAh battery capacity is ample for most needs, and should be enough to charge a phone at least twice.
It comes with a USB-C to USB-A cable, but for top speeds if you have a USB-C Power Delivery (PD) charger or USB-C laptop, you’d be wise to invest in a USB-C to USB-C cable, too. EasyAcc also sells a USB-C to Lightning cable (from £12.99 or US$13.99) for fast 18W charging of iPhones.
There’s even a pretty bright flashlight included for emergencies or trying to connect in the darkness.
6. Iceworks 7000
The Iceworks 7000 is a very similar setup to the Flux Charger below, with a lower price and easier availability, but just the one built-in cable.
The version we're testing is a USB-C model, with that being very much the standard for new Android phones today, but it does rule out iPhone users and those running older Android phones with a Micro-USB connection.
The Iceworks is a fast charger for your phone or tablet, with both input and output rated at 15W. The output is of the USB-C variety too, so you can use your standard phone charger to juice it up in around four hours, and it'll recharge while charging your connected phone.
Perhaps more interestingly, the USB-C input is also an output, so you can actually charge two connected devices at once if required.
The design is good, but while it's just 9mm thick it still feels rather large for a 7000mAh power bank (of which you'll see around 4,550mAh). It's taller and wider than our connected Galaxy S8 at 156x78mm, which makes it feel less comfortable when stashed in a pocket.
But assuming you'll be throwing this charger in a bag it won't weigh you down at 159g, and we like not having to carry separate cables. You don't really need it, but the mesh carry case supplied in the box is a nice touch.
7. QDOS AirBank Qi Wireless PowerBank
One of many such devices now coming on to the power bank market, the 5,000mAh AirBank is able to not only charge a device attached using a USB cable, but it can also wirelessly charge compatible smartphones.
It has an interesting design with 12 rubber suckers (six on each side) to hold your phone in place, which makes it very practical but is easily caught on the lining of your pocket and, let's be honest, looks a little odd. Still, we can't complain it's just another boring black plastic power bank.
We'll see more and more of these wireless power banks coming on to the market, and you will almost certainly be able to find cheaper - and faster - examples.
The AirBank supports Qi charging up to 5W, which is painfully slow. Wireless charging has moved on since the days when this was the maximum possible, and many new flagship phones are beginning to follow suit.
If you can't bear to wait so long to charge your phone then there's also a full-size USB output rated at 2.4A, offering 12W charging for a connected phone. You could even charge two devices at once, although the capacity is not sufficient to fully charge more than one.
QDOS' AirBank will work with phones in their cases provided they are not more than 3mm thick, and at up to 6mm distance. Although it says the device must be plugged into a power source for wireless charging to work, we found it would wirelessly charge our phone when running on the battery too.
8. Aukey 20,000mAh USB-C Power Bank
Aukey's 20,000mAh power bank is appealing for three reasons: its price, its large capacity, and its number and variety of ports.
You get three full-size USB outputs, as well as a single USB-C. You can also use this USB-C port to recharge the power bank, which is the fastest method, or you can use a Lightning or Micro-USB input (the latter oddly hidden around the corner from the other ports), so it will work with whatever cable you happen to have to hand. For what it's worth a USB-C cable is supplied in the box.
This isn't going to be the fastest power bank for charging multiple devices, however. While the USB-C can output up to 3A (15W), the remaining three outputs must share the same amount between all three. So if you plug in three devices they are each going to charge at a slow 5W. Still, all those ports could prove very convenient if you have multiple devices.
And if you are charging more than one device then you're going to need lots of juice. With a rated capacity of 20,000mAh you can expect around 13,000mAh to be available to your devices. That might charge an iPhone seven times, or a typical Android phone four times.
Once depleted the large battery will take 10 hours to recharge, though you can continue charging attached devices in the meantime.
The trade-off for all this power is size, and this Aukey charger is huge. It's much larger than our phone at 200mm long and 96mm wide, though also reasonably skinny at 14mm. It's as heavy as it looks at 435g, and feels quite bulky.
The design is also rather basic, a matt black plastic slab with a shiny plastic bumper running around the circumference. The Aukey logo is printed on the front and four small LEDs are visible on the side to show how much power remains.
9. Flux Charger
We've included the Flux Card power bank in this round-up because it's a great example of an all-in-one power bank, though it's not the easiest device to get hold of in the UK.
Right now it's on offer at $29.95 (£23.45) on the company's website (down from $39.95/£31.28), but if you want one in the UK you should also factor in $9.50 (£7.44) shipping and the fact you may also have to pay Customs charges.
When we say 'all-in-one' power bank we mean one that includes all the necessary cables for charging your device, resulting in a much sleeker overall package. Typically such devices make you choose Micro-USB or Lightning, but this power bank supports both. All that's missing is USB-C.
It's slim, portable and, since we wrote our original Flux Card review the company has updated its device, now clad in durable black or white aluminium rather than plastic, and still incredibly thin at 7.8mm. It weighs a tiny 88g.
It has a 4,000mAh capacity, which is going to be good enough for a full charge for any phone, and it's reasonably speedy with a 7.5W input and 10.5W output. Passthrough charging is supported, which is a nice extra.
In common with nearly every power bank you'll find today Flux offers four LEDs to show how much power remains, and boasts smart technology to recognise your device and deliver an optimum charge.
Read our full Flux Card review
10. Moshi IonSlim 5K
Another model from Moshi, but this time suitable for everyone, is the 143g IonSlim 5K. It's just as expensive as the IonBank 3K, costing £54.95/$54.95 at Amazon, but packs in more power with a 5,150mAh battery. (There's also a 10K model if your pockets are especially deep.)
A lot of what you're paying for here is the design, and the aluminium-clad IonSlim is a crazy 8.5mm thick - that makes it just a fraction thicker than the USB output found at one end.
There's also a USB-C port, which is both input and output. It's fast at 15W, which means charging the power bank itself doesn't take significantly more time than charging your phone, but we'd have been more impressed were it to provide support for passthrough charging.
Other features are reasonably basic, and this is one of few recent power banks we've tested not to support auto-on. You'll need to plug in your device and then press the power button, which just seems like an unnecessary extra step in this day and age.
Learn more in our full Moshi IonSlim 5K review.
Read our full Moshi IonSlim 5K review
11. RavPower PowerStation 20,100mAh
This RavPower PowerStation sits at the bottom of our chart not because it's not any good (actually we wouldn't recommend anything here we wouldn't personally own and use ourselves), but because for most users it will be overkill, and probably over budget. The PowerStation is available from Amazon for £89.99/$95.99, and there is plenty here to warrant that somewhat extravagant price.
The PowerStation stands out for its inclusion of an actual plug socket - and not a US or EU two-pin plug that you need to pair with an adaptor, but an actual UK three-pin plug, rated at 65W. These things are hard to come by. (That said, if you need a two-pin version there's also the £119.99/$129.99 RavPower PowerStation 27,000mAh version, reviewed here.)
As well as the plug there's a 19V/1.6A DC jack for significantly faster recharging - despite its huge capacity you can recharge this bank in just four hours, when a comparable bank might take 13 hours over a standard Micro-USB input.
At 69x69x146mm this power bank isn't going to fit in anyone's pocket, but it does come with a hard mesh case and all the necessary attachments (including some carabiner clips). And it does have enough power to fill an iPhone seven times, and most Android phones four or five times.
Now you're probably not want to carry your actual phone charger with you to plug into this thing, but RavPower has you covered here too with a 15W USB-C output and 12W 'iSmart' USB output. Both these ports are pretty fast, if not Quick Charge fast.
This is a reddot award-winning design, and we love the soft-touch rubbery finish and rounded corners that make it feel less unwieldy and prone to damage. A plastic LED strip running around the middle breaks the black, and the small vents top and bottom help with heat dissipation.