Frequently Asked Questions

How Can I Buy GravityLight?
We’re interested in selling or distributing GravityLight.
Can we take part in the user trial?
We want to use GravityLight as our basis for an education project. Can I get a sample?
How did you come up with this idea of GravityLight?
How does it work?
What is the power of GravityLight?
More technical characteristics?
I have an idea to improve it. Have you thought of changing x, y, z? Can it power other things?
How much is the cost of GravityLight?
What is the social impact of GravityLight?
How do I install GravityLight and SatLights?

1. How Can I Buy GravityLight?

Many thanks for your interest in GravityLight. Commercial availability of the product is planned for 2015, once our user trials have been completed and the product has been fully optimized for volume production. Please enter your email address below to join our mailing list, which we will use to update you about availability. We’d love to stay in touch, so please join.

2. We’re interested in selling or distributing GravityLight.

Many thanks for your interest in GravityLight. Same thing than above, commercial availability of the product is planned for 2015, once our user trials have been completed and the product has been fully optimized for volume production. We are receiving a lot of enquiries about distribution and we will be selecting the right partners in a few months time. In the meantime, if you could share with us some further information about your company and any external partners, it would help us understand your position as a potential distributor. Please contact us at info@gravitylight.org

3. Can we take part in the user trial?

Sorry no. All our lights for the trial have now been allocated and the trials are well underway. Please join our mailing list to be updated about commercial availability, which is planned for 2015.

4. We want to use GravityLight as our basis for an educational project. Can I get a sample?

Unfortunately due to very limited stock we do not have samples to send out, but we hope that the following links to some GravityLight media will give you further information to help with your project.

5. Can it power other things? I have an idea to improve it.

GravityLight stemmed from a challenge by the charity Solar Aid to design an LED lantern to replace harmful kerosene lamps. The brief was to develop a light with a photovoltaic panel and battery for under $5. However, as we looked at the basic cost of materials it became clear that it would not be possible to meet the target price point. We realized that the key would be to design a light that didn’t need batteries, which were driving up the cost, had a short life span and were not the most efficient use of energy. Looking at the market resistance to manually powered alternatives such as wind up radios or pedal-powered lights, we also wanted to find the right ratio between time spent and power generated. Martin looked to weights and gravity. First proving the concept with a rig of bicycle wheels, chains and a hand crank torch he was confident that it could work. Years and many prototypes later, we’re ready to produce our first batch. Even with the 0.1W of power it produces, GravityLight produces a light superior to kerosene lamps and can also power various other low-power devices such as torches and radios.

6. How does it work?

After the bag has been lift-up by human force, The gravity exerts a force on a weight and while the weight is descending under that force, this kinetic energy is converted via a series of small gears into electrical energy and the light is powered live. There are no batteries in GravityLight. The duration of the drop is 28min on low light, 20min on medium and 12min on high. It can be used over and over with no running costs.

7. What is the power of GravityLight?

To this question there are two answers: the power output of the GravityLight in Watts, and the Lumens/Watt of the LED. The power output is (with a 12.5kg load) H: 0.1W, M: 0.075W and L: 0.05W. The lumens/watt of the LED is in the region of 100 l/w. So on High you will have about 15 lumens output, Med about 10 lumens, and Low about 5 lumens. The advantage of an LED light source over a kerosene lamp is that nearly all this light output can be directed at a task or onto a surface. This idea of ‘useful light’ requires a more appropriate unit of measure than ‘Lumens’ (total light output). Lux is the unit for light falling on a surface (lumens/square meter). As a rule of thumb, the numbers for lumens/watt given above can be used for the GravityLight Lux output: variable between 5 and 15 Lux. As a comparison, a basic kerosene lamp is quoted as providing between 1 and 6 Lux. The power & duration can be adjusted by the users on this first version of GravityLight via a power dial on the front.

8. More technical characteristics?

Power (max): 124 mW Operating Temp: -30 ~80 °C Storage Temp: -40 ~100 °C Luminous Intensity: 13.8 cd* *Luminous intensity value as per CIE 127:2007 standard (If=20mA) Product Dims: Weight: 0.8kg H:160mm, W:103mm, D:78mm Load Weight: Minimum: 8.0kg Maximum: 12.5kg Power Output (12.5 kg load): High: 0.10W Med: 0.075W Low: 0.05W So at the moment the technology is ranging between 0.05W and 0.1W.

9. I have an idea to improve it. Have you thought of changing x, y, z? Can it power other things?

Thanks for your curiosity and your willingness to help push the technology forward. The GravityLight can work with other other low power devices, thanks to its DC socket in the back. We are currently working on it as well as other developments. We are very keen to have the best possible access to GravityLight technical details and build an open innovation community. We are exploring options and the first of them is this online open innovation community. For now it is reserved to the initial pledgers on indiegogo who have also received a GravityLight. Pooling together knowledge from all around the world and building on each other idea we should be able to improve the technology faster and thus improve the social impact in developing countries. In the future, depending on how this prototype forum is going on and as the commercial availability of GravityLight is approaching, we should open the forum to everyone. In the meantime, you can still contact us on info@gravitylight.org.

10. How much is the cost of GravityLight?

Our aim has always been to make an affordable alternative to kerosene lamps and design GravityLight to keep costs to a minimum. The market retail price is yet to be finalised, and it will probably not be the same everywhere, country by country according to local circumstance. It will also go down with time as we scale our volume of production. Although GravityLight may represent a high upfront cost for some families, given it has no running costs it would pay for itself within a few months, weeks for some, of not needing to buy kerosene for light.

11. What is the social impact of GravityLight?

The impact will be beneficial for the social, health and economic situations of end users; the economic situation of local distributors and everyone on earth as replacing kerosene lamps with a product free of any fuel will reduce greenhouse gas emissions and thus reduce climate change. In conceptual terms we aims at a positive triple bottom line: social, environmental and economical for all stakeholders. and us. A complete report from the large scale field trial should be available in the spring 2014. Another impact of GravityLight, through an open innovation community that we aim to build will be to foster the development of a new market and a new area of research.