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 gear train 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.