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GravityLight

posted by Jason Kottke   Aug 04, 2015

GravityLight is an electric light that draws its power from gravity. You lift up a weight attached to the light and as it falls, it generates enough power to light the light for 20 minutes.

GravityLight is installed to provide a 6ft/1.8m drop of a 12kg weight. This weight is lifted and on release starts falling very slowly (about 1mm/second).

This movement powers a drive sprocket, which rotates very slowly with high torque (force). A polymer geartrain running through the product turns this input into a high speed, low torque output that drives a DC generator at thousands of rotations per minute.

This generates just under a tenth of a watt, a deciwatt, to power an onboard LED and ancillary devices. Given the ever-increasing efficiency of LEDs, this produces a light over 5 times brighter (lux) than a typical open-wick kerosene lamp.

Once the weighted bag reaches the floor, which depends on how high it was installed, it is simply lifted to repeat the process.

(via @craigmod)