When it looks like your phone is about to run out of battery, you actually have plenty of juice to spare. The Voltmaker is a device that allows you to make use of that reserve energy in order to charge your phone — all with the flick of a wrist.

A hidden rod that is normally secured to the body using a magnet can be released using a spring-loaded mechanism. Once you release it, you can spin the rod by shaking the device like a rattle — a movement that allows your smartphone to harvest kinetic energy.

By keeping up your enthusiastic rattling for a few minutes, it’s possible to generate enough power to make a quick phone call, play a couple of songs or light the way using an LED torch attachment that fits into the USB port at the opposite end.

Image courtesy of The Voltmakers

Using this method to fully charge the device would take two to three hours — more shaking than your wrists can probably handle. For this reason, the creators of the Voltmaker recommend charging the device using a USB connection for everyday activity. Kinetic energy should be harnessed when your phone's charge is low, but you can't access a power socket or USB port.

The company has set a $200,000 funding goal on Indiegogo and has promised a refund to anyone who pledges if the campaign is unsuccessful.

Check out the Voltmaker's campaign video below:

Image courtesy of The Voltmakers

This article originally published at PSFK here