Irish coffee chain Insomnia has introduced devices that allow customers to charge their phone for free.

The 'WattSpot' boxes feature five charger plugs on the side to fit most mobile devices.

The charging ports are currently compatible with the iPhone, HTC and USB ports.

"The feedback we have received has all been positive, with many customers complimenting the idea and hoping that others will get on board with this innovative service," Insomnia says.

The boxes are the brainchild of Dublin psychology student Conor Nolan (20).

Mr Nolan set up 'WattSpot' with a friend, after noticing a gap in the Irish market.

Insomnia currently have the service in a number of Dublin stores.