The GravityLight was designed to replace the use of kerosene lamps in the developing world. It uses a weight to drive a gear-train and generate electricity from the kinetic energy created. Now, a new version of this safe, cheap and convenient lighting solution has been created.
The original GravityLight is hung in a room and a weighted bag attached to a hook at its bottom. The bag, which is filled with rocks or sand, is winched up and then gradually descends at a rate of about 1 mm (0.04 in) per second. This powers a low-speed high-torque drive sprocket, which when run through the gear-train is able to drive a DC generator at thousands of rotations per minute.
The process is said to generate just under a tenth of a watt, a deciwatt, which is able to power an onboard LED and ancillary devices. The LED is reportedly able to produce five times the brightness of a kerosene lamp and once the weight hits the floor, it can simply be winched back up for the process to be started again.
The company behind the GravityLight says it received lots of feedback about the first version and has been able to improve it accordingly. The new version of the device is said to be easier to use, brighter, more robust and longer lasting.
A new pulley system has been incorporated so as to make it easier for users of any height or strength to lift the weight right up, giving the maximum drop-time. Trials found that some users could not do this with the original GravityLight. The pulley system also means that the light can stay on even when the weight is being lifted, something that wasn't the case previously.
The LED in the GravityLight 2 is said to be brighter than the previous version, but twice as energy efficient. The three different brightness settings, which were found to be largely unused, have been done away with and the light will now stay on for 1.5 times as long.
Finally, GravityLight says it has addressed some of the wear-and-tear issues that some users of the first version had reported. After testing different materials, gear geometries and arrangements, the company says the new design will last longer.
An Indiegogo crowdfunding campaign has been launched to set up assembly facilities for the GravityLight 2 in Kenya. At the time of writing, pledges for a GravityLight 2 are available at US$70 or more. If all goes to plan, delivery is estimated for May 2016.
You can see the pitch video below for the GravityLight 2.
Sources: GravityLight, Indiegogo