Here's a smart idea. The Griffin PowerBlock Reserve – something around the size of a thick bar of soap – comes with US and UK socket adapters, and outputs 5V/1000mA, so it'll charge pretty much any USB device you plug into it.
(Exception: while it will charge the iPad, it does so very slowly. It would take three days to charge it fully. Rest assured, Griffin's on the case.)
The clever bit is that part of the PowerBlock Reserve pulls away; it's a little battery with a standard 30-pin dock connector that you can use to give your iPod or iPhone a jolt of power when away from the mains.
The battery is held in place with a couple of magnets, though when used with the UK plug, it sits on top rather than hanging underneath so the magnets aren't so important – and as it's charging, a row of five green LEDs show its level of charge.
But while you can press the battery icon to see the charge level when it's connected to the mains or a device, it doesn't show it when it's not.
Of course, the PowerBrick Reserve charges a connected device and its own removable battery at the same time.
This battery is a bit weedy, though. With only 500mAh capacity, it won't fully charge an iPhone battery, though it was sufficient, in our tests, to make an iPhone properly last an entire day away from the mains, even when being used heavily.
The Griffin's only a fiver more than Apple's own USB charger, too, with the bonus of the battery and US/UK compatibility.
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