In the age where your mobile phone is also your camera, your MP3 player, your portable storage device and hopefully soon an all-in-one breakfast maker, it is refreshing to see that some phone accessories are still keeping it simple. Energizer's Energi To Go is a portable charging device for your mobile, and that's about as simple as it gets.

Running off two AA batteries, it can be a lifesaver for those who are regularly on the road. You can't always find a power outlet when you need one and business users in particular will appreciate having their smartphones up and running at critical moments.

The unit is extremely basic, just a small curved battery case with a jack at the top that accepts a variety of adapters. There are adapters available to suit the majority of mobile phone manufacturers, including Nokia, Samsung, Motorola and LG. Mini-USB is also an option, although you don't get all of these together in the one box so be certain to purchase the appropriate package.

It is very sturdily built and is fine to just throw in your bag and forget about it. It's tiny too at around 10cm long and 3cm thick, so it's perfect regardless of how much bag space you have.

There are no controls present, you simply unclip the tip of the case, insert the batteries and you're good to go. Plugging it into a completely dead phone will have it up and running in around 30 seconds, which is comparable to a standard AC phone charger.

The unit comes with two non-rechargeable Lithium batteries, which are recommended by Energizer. While they do last longer than regular Alkaline AA batteries they are also more difficult to find so some consumers may struggle to utilise this device to its fullest.

Energizer doesn't give an exact figure regarding how many charges you'll get out of a single set of batteries, but smartphones will get slightly less than regular phones. Typically, we found we'd get several charges on our regular mobile handset before needing to change batteries.