Festival season 2013 is upon us, but will your phone last a full weekend? Worry not: we're trialling the future of mobile charging...

recharge bag

Festival season is upon us! The Isle of Wight festival kicks off tomorrow and stretches into the weekend, but, as any festival goer knows, that can be bit of an ask when it comes to keeping our phones full of juice. But what if you could charge your kit while you walk, dance and sleep?

Vodafone’s always been at the forefront of festival charging tech. One of our Recharge-Trucks, which is capable of charging 2000 phones at the same time, will be at the Isle of Wight and a host of other events throughout 2013, but now we’ve decided to go one further with wearable tech that powers your peripherals with nought but your body heat and movement.


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Enter the Power Pocket – built into Power shorts and the Recharge sleeping bag, which we’ve developed with the Electronics and Computer Science Department at the University of Southampton. We’ll be trialling them both throughout the festival season, but before we do we thought it’d be a good idea to speak to the man behind the pioneering tech to find out how it works…

The science

“We’ve been working on printed smart material since the late 1980s,” says Stephen Beeby, Professor of Electronic Systems at the University of Southampton. “But that was high-temperature stuff designed to be used on ceramics. We got into the topic of energy harvesting in the late 1990s, and we brought the two together to make smart materials for harvesting energy.”

“We started on thermoelectric materials in 2003, but our printed thermoelectric material work has only been the last few years.”

“One side of that is cold and the other is hot, and when you get a flow of heat through it you can create a voltage.”

Stephen’s team’s research has culminated in thermoelectric material that’s so small it can be stitched into a pair of shorts or, in the case of the Recharge, a sleeping bag. But how does it work?

“Basically, we’re printing down pairs of what are called ‘thermocouples’,” he explains. “You print lots of those down and connect them up to make a thermoelectric module.

“One side of that is cold and the other is hot, and when you get a flow of heat through it you can create a voltage and a current. Voltage and current together equals electrical power.”

Got that? Your body provides the heat on the inside layer, and it’s the difference between that temperature and the colder one on the outside that provides the power. This is called the Seebeck effect.

The kit

Crucially, when you connect that power up to a phone or tablet, you can juice it up.We’ll be trialling the Power Pockets and the Recharge sleeping bag through the festival season, to see how they fare as the future of festival power. But, as Stephen explains, even the results so far will be music to the ears of any ardent festival goers:

“Eight hours in the sleeping bag, roughly speaking, will provide 24 minutes of talk time and 11 hours of standby time. That’s assuming the inside of the sleeping bag is 37 degrees – human body temperature.”

Likewise, a full day of walking and dancing in the Power Pocket shorts will charge a smartphone for four hours. Not a bad day’s work.

The future

power pocket

So where’s this tech headed? Everywhere, according to Stephen and his team – although there are some things still to fully iron out. Thankfully, trials like this will help:

“There’s lots of research still needed around making this technology hardwearing,” he says. “Sleeping bags, for example, need to be folded up and compressed into quite a small package. These materials at the moment are flexible, but there are improvements to be made still.

Even so, he’s confident that the future of clothing and the future of technology are going to merge at some point in the near future…

“There are researchers around the world doing similar things right now, though, and I imagine that this technology will be implemented routinely into clothing and things like that over the next ten years.”

Any questions? Let us know below!