A chunky charger - but even bigger on the inside,
This review is from: EC Technology 13000mAh External Charger for Apple and Android smartphones and tablets - Black (Wireless Phone Accessory)
It's great to have a mobile device with GPS, Wi-Fi, Bluetooth and 3G/4G, but these devices use up power at quite a rate, and one of the least convenient things about a mobile phone is having to plug it into the wall to charge. Even more so if you're out on a hike and there is no wall to plug into!
This charger comes in several sizes, and I have the black 13000 mAH version. That's 13 Amp Hours, or in real terms and after allowing for energy lost to heat around 9 hours of a 1 Amp current, which is a lot of charging. If you're using a tablet and you need more current, there's a 2.1Amp USB outlet too, and you can use both the 1 Amp and the 2.1 Amp outlet simultaneously.
It's quite a chunky unit, with a sort of rubbery coating and rounded edges, and with a minimal 4-light charge display, a "start charging" button (if you press it twice a white LED comes on that you can use as a rudimentary torch), the two USB outlets on an end and the micro-USB charging input on one side. That's it; it's functional and not at all flashy. Note that the unit charges at 1 Amp, which allows for better battery charge but takes longer - it will take about 12 hours to fully charge this pack from flat.
There are some cables included with the charger, including the vital micro-USB one to charge the unit itself. Not every possible form of cable is included (and - apparently due to licensing issues - an Apple Lightning charging cable is one of the cables not included). But of course you get the correct cable with your phone/tablet/whatever, so that's shouldn't really be too much of a problem.
The thing about a battery pack of this size is that it can keep a typical smartphone (I use a Nexus 4) going for about a week - depending on how much you use your phone, of course - and it can keep an iPad going for much longer than a typical 5,000mAH charger. It's definitely worth going for a higher-capacity pack like this, even if it is a bit heavier and thicker. It's still only about the same size as my Nexus 4, and about 2.5 times as thick.
Note: EC Technology kindly sent me one of these battery packs for review purposes.