Just about every gadget, from your mobile phone to your digital camera, takes batteries; and no matter how prepared you think you are, batteries have a habit of failing just when you really need them. This normally happens when you have no way to charge them, too.

These clever little devices, however, just might be the answer. The slinky pocket-sized cell of the Pocket Charger houses two replaceable AA batteries and has connection leads for an iPod and a mini USB port, allowing you to top up MP3 devices, phones, PDAs and even compact cameras (with USB charging facilities) to allow you to keep on using them.

The more expensive Instant Charger version (£24) uses an internal 5Volt 1000mAh battery that can be recharged by plugging it into a computer USB port, but lacks an iPod lead.

Now, with relatively small battery power, neither are likely to completely refill a dead battery, and not all cameras will allow charging via this method. But as a provider of emergency power for phones and iPods it is perfect and, at just £15, has already more than paid for itself in place of lost communication or otherwise music-free train journeys home.

We’d just like to see a larger version released to deal with our more power-hungry appliances.