Once you start relying on your smartphone for more than phonecalls and text messages, you start to fret about battery life. Want to stream music and video, record a meeting or play games all the way home on the train? You'd better remember to plug in at some point. And tablets may be thin and light with good battery life, but thin-and-light means a battery you can't replace, so you have to carry a power supply instead of a spare. If you're planning on watching movies on your iPad on a flight, it's frustrating to get halfway across the Atlantic and run out of juice.
The answer is to pop a rechargeable battery charger in your bag; they're smaller and lighter than a power supply and don't mean spending half an hour sitting by a power socket. There are plenty of them on the market these days, but while Innergie's PocketCell isn't the cheapest (at £79.99 inc. VAT) it's small and neat with styling reminiscent of Apple and several neat features that help it stand out.
Four blue LEDs on the side of the sleek white case do double duty to tell you when the PocketCell is charging and how much power it has (when you tap the small button). You have to press and hold the button to turn it on, so it's not as likely to run down in your bag; it also goes into Sleep Mode if you don't plug it in within ten seconds or (more likely) forget to turn it off when you unplug your phone. There's a lanyard hole so you can hook it onto your bag so you don't drop it, and putting the Micro-USB charging port on one end and the USB power out port on the other is much neater than devices that stick the ports along the side.
Many of the smaller portable chargers only have a 0.5A port, which will recharge your phone or MP3 player; the PocketCell delivers the 2.1A you need to charge a tablet. And the really clever bit is the three-in-one Magic Cable Trio. One end of this is a standard USB port, while the other has adapters for micro USB, mini USB and the Apple dock. Instead of hanging loose and getting in the way, or having the usual handful of removable adapters that you can leave behind or lose, these three adapters are hinged, one on top of the other (see above). Pull a little and the adapter you don't need snaps off the one underneath and hinges out of the way; you simply snap it back into place when you're done. You don't get adapters for older, proprietary connections like Nokia, Samsung and Palm devices, but if you have a USB cable with the right adapter you can just plug that in instead.
The PocketCell's 3,000mAh capacity is good for something this small and neat — there are plenty of 2,000mAh battery packs that are bigger and bulkier. Innergie calculates that's enough to give you an extra 70 hours of music on your iPod, 4-5 hours for a tablet and at least 15 hours for a smartphone (25 hours if you're talking rather than playing games). In our tests, we got a full charge for a smartphone with enough power remaining to top up a second phone. The larger battery in a tablet gets between a quarter and half charge, depending on the size of the battery you're topping up.
The PocketCell comes precharged so you can use it straightaway; when it needs charging that takes a couple of hours plugged into a laptop's USB port — or rather less if you have a mains USB charger handy.
The PocketCell has plenty of competition, most of them cheaper (many of them no-name brands). What you're paying for here is good design and real convenience.