# The Gravity Light



## zespectre (Dec 21, 2012)

I stumbled upon this and thought it was interesting enough to mention. These guys are trying to develop a gravity powered LED light/charging system for undeveloped areas that will be more effective and safer than what is currently being used.

I have absolutely no connection with this project or their fundraising efforts, I just thought it was a neat concept.

Article on the Gravity Light.

Their Indigogo page (with a video)
The Gravity Light (Lighting for undeveloped areas)


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## Outdoorsman5 (Dec 21, 2012)

Man, this is cool & awesome. I hope their plan works with this, and these end up all over the world.


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## Jalben (Jan 15, 2013)

Super cool. Like a grandfather clock light.


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## enomosiki (Jan 15, 2013)

This is an excellent concept.

I'm wondering, however; how sturdy will it be? I mean, it's constructed out of plastic and relies on heavy object pulling down to power it, so I'm guessing that longevity might be an issue here.


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## slebans (Jan 23, 2013)

*Duo create GravityLight: LED Lamp that runs off of gravity*

Duo create GravityLight: LED Lamp that runs off of gravity
http://phys.org/news/2012-12-duo-gravitylight-lamp-gravity-video.html

Interesting article! If you want to calculate how much weight you would need to move through a distance to power the lights in your house - here is a simple Online calculator:
http://easycalculation.com/physics/classical-physics/potential-energy.php

Perhaps you could invite your relatives over more often - as long as they agree to the House Exercise Labour Plan!


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## SemiMan (Jan 24, 2013)

This is a great idea for people who don't understand physics.

Let's assume a 25KG weight (that is quite a bit to move)
1.5 meter height

That has 367 joules of potential energy.

With 100% energy conversion, for the 30 minutes they claim, that will put out 0.2 watts. Can you make a usable light with that? Probably, but would you want to?

Give me a solar panel and battery any day. No moving parts to fail. Small, compact, and a single 1.3AH, 3.2V LiFePO4 stores 14000 joules that I can recover 100% of or about 40 pulls of a 25kg weight. I guarantee that battery will likely need to be replaced less often than these units.


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## AnAppleSnail (Jan 24, 2013)

SemiMan said:


> Give me a solar panel and battery any day. No moving parts to fail. Small, compact, and a single 1.3AH, 3.2V LiFePO4 stores 14000 joules that I can recover 100% of or about 40 pulls of a 25kg weight. I guarantee that battery will likely need to be replaced less often than these units.



I'm not so sure about the service life being so short. There are all kinds of sculptures with motor-driven joints that move far more often than twelve times per day for decades. And properly-made plastic-housed device can be quite durable. Just look at many modern firearms with "polymer" bodies. At reasonable loads, even nylon bearings work for plenty of service hours. I have to admit I haven't tried nylon bearings with 25kg weight - Only 5kg. The gears concern me though, as I've had (poorly specced) gears fail in "polymer" (And metal) drivetrains.

I'd like to see a version made of scraps. The benefit here (And in the lights) is that you make it out of things that are laying around. Unless you're in a semiconductor lab, you don't have solar panels and LiFePO4 cells sitting around, nor do you want to wait to see if your village is one of ten thousand that gets a light.

[There are economic considerations for and against shipping in electronics, but that's neither here nor there]

The plan of using some know-how and scrap parts (small motors from broken things?) to create lights is a huge benefit to areas that may have cell coverage and little other infrastructure. And in the middle of unlit areas, 0.2W of light is quite a lot, especially if it's built of scraps and an imported LED. Having them produced and imported won't serve as many people, but it sure makes good press.

Solar panels have some good selling points, but battery maintenance AND low system cost rarely come together. The cycle limit of the cell can be helped at the expense of system cost. The charging capacity can be cut to reduce cost, at expense of cell health. Mechanical to electric could be easy to debug and fix, but not built the way their prototypes show.


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## Pöbel (Jan 24, 2013)

You may also consider that areas in need of that device will often not be as clean as a lab or our homes. So there is dirt, sand and stuff. I don't know how far plans go in protecting the device from environmental impacts, but that might be a deal breaker. While those plastic parts will hold up quite well when clean, sand could dramatically change that expectation.


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