You use your phone a lot. It runs out of battery. You cry. Solve that.
I've spent a lot of time testing a lot of USB power banks, USB batteries, portable USB chargers or whatever you want to call them. I use a lot of gadgets, and I use a lot of power, and I have an obsessive need to keep everything topped up to a 100 per cent charge. Over my years of testing, these are my absolute favourite portable USB power banks.
I know it's a weird thing to have a favourite of, but it's like a good pair of shoes. A good power bank is reliable, does exactly what you need, and doesn't get in the way. And that means no funky shapes, no flimsy designs -- just a box full of batteries that works every time you need it to.
I don't mean for this to be the be all and end all of USB battery hot takes, though. I'm pretty confident of my top picks, but do you disagree? Is there a better one out there that you've used? If you've got any other suggestions, feel free to drop them into the comments!
The $99.95 Cygnett ChargeUp is a rubberised power bank with a strong plastic shell and a tiny LED display near its power button. It has two USB-A ports for charging at a total power output of 4.2 amps (2 ports at 10.5 Watts, 5V 2.1A) so you'll be able to top up two power-hungry devices at a reasonable pace simultaneously. Recharging happens over its microUSB port.
It's the smallest and slimmest of the three here, and has curved edges that mean it won't scratch your phone screen if you're keeping the two in the same pocket while it charges. Its coup de grace, though, is that small screen that shows you the percentage of its state of charge: the best possible way to find out how many more boosts you have in store for your phone.
Cygnett sells the ChargeUp in 10,000mAh, 6000mAh and 4000mAh capacities with that very useful state-of-charge display, and as a Sport version that's a little chunkier and more rugged but without any status read-out on how full or empty it is. And there's also a small Pocket version that has a built-in microUSB cable.
The circa-$50 Tronsmart Presto is the cheapest of this set of three, but it's not the least technologically advanced. If you're blasting through charges for multiple devices over and over, you'll really like the fact that the Presto is Quick Charge 3.0 (15 Watts, 5V 3A) compliant through USB-C -- so it'll charge itself very quickly from any half-decent wall charger, and then deliver that charge just as fast to your phone.
I use the Tronsmart Presto with my sexy sexy Belkin DuraTek USB-C cable and it is phenomenally good at quickly charging two things: my Telstra Nighthawk M1 hotspot and my Samsung Galaxy S8 Plus. Both have pretty good battery life on their own, but I am the definition of heavy user, and the USB-C charging means they both get topped up very quickly.
Only one caveat: the Presto is quite large, a little bit ugly, and it's only available in a 10,400mAh capacity. [Tronsmart Presto]
The $119.95 Belkin Mixit is a sturdy piece of kit. It's wrapped in a metal shell, has two USB-A power output ports and microUSB recharging, and supports 4.8 amps' (2 ports at 12 Watts, 5V 2.4A) total output -- which means you can charge two devices simultaneously at the full potential of the (regular, non-Quick Charge, non-proprietary) USB standard.
The bets feature of the Mixit is that if you're charging a microUSB phone, you can keep that cable hidden away and charge your phone when you need it, then charge the power bank itself from any wall outlet. Plus, you can buy one in gold. Why would you not want one in gold?
You can buy the Mixit in a USB-C version too, although only in a 6600mAh battery size. Without the integrated charging cable, you can also find the Mixit in 10,000mAh, 6600mAh and 4000mAh capacities. [Belkin Mixit]