The Basics

GravityLight is powered by the lift of a weight.

As the weight falls it turns a gear train, driving the motor that powers the LEDs.

GravityLight doesn't need batteries or sunlight and costs nothing to run. It takes seconds to lift the weight that powers GravityLight, creating 20 minutes of light on its descent.

  1. Fill the bag with weight (about 12kg)
  2. Lift the bag using the orange cord
  3. Bag falls slowly creating light (about 20 mins)
  4. When the bag reaches the ground it can be lifted again.

The Detail

GravityLight is installed to provide a 6ft/ 1.8m drop of a 12kg weight. This weight is lifted by a person pulling the orange cord. A pulley system means the weight only feels like 3kg. Once lifted, the weight then falls very slowly (about 1mm / second).

This movement powers a drive sprocket, which rotates very slowly with high torque (turning 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 1600 rotations per minute.

This generates about a tenth of a watt to power the onboard LED and two SatLight LEDs. Together these produce a light more than 5 times brighter than a typical open-wick kerosene lamp.

Once the weighted bag reaches the floor (after 20 minutes), it is simply lifted to repeat the process.

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The Benefits of GravityLight

+ Instant light, any time

It takes just a few seconds to lift the weight that powers GravityLight. There's no need to charge in advance, it's ready when you need it. We have incorporated a pulley system so users of any height or strength can lift the bag right up to the top - giving the maximum drop time.


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Use of GravityLight does not depend on a person's strength or their height


The technology behind our pulley system makes GravityLight accessible to all, but also offers the key benefit of allowing the product to stay on whilst the unit is recharged by a bag lift - this means that GravityLight can give continuous light throughout the evening.


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The light stays on even when charging (as long as the bag doesn't touch the ground)


+ No running costs

As the energy generated from the device is completely self sustained, GravityLight pays for itself within months of switching from a kerosene lamp.
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+ No sun or batteries needed

No batteries mean that GravityLight can be stored indefinitely, without the risk of batteries degrading.

With no need for the sun, it can be used whatever the weather outside.

+ Robust and reliable

It's important that the drive system is protected should an extremely heavy load be applied - we found that children really enjoyed swinging on the GravityLight bag!

An entirely novel way of protecting the system has been designed for GravityLight. It will allow an overloaded bag to descend to the ground in a safe and controlled manner.

We have carried out an extensive series of product life testing. We experimented with different materials, gear geometries and arrangements and now have a design which will go the distance!


Learn more: Videos

Watch the video to learn more about the inner workings of GravityLight!

Ever wondered what a GravityLight is and how it works? Watch our step-by-step guide.


Specification and Compliance

GravityLight is tested and compliant with numerous industry standards. Producing a light over five times brighter than a typical open-wick kerosene lamp, GravityLight offers a safe alternative to kerosene.