Here is a link to a story about a gravity powered light/generator...Maybe not the answer for a lifetime, but could be handy in an emergency situation...Hope it catches on..rsbhunter A Lantern Powered by Gravity | This Could Be Big - Yahoo! News
That is actually quite clever. I see battery charging for cell phones and laptops for possible development planning, as well as lighting. What I didn't see is electrical specs. Put me in the interested group.
That looks pretty neat. I would like to know the run time and if the light/energy output is determined by the weight added to it. Found the answer: GravityLight: lighting for developing countries. | Indiegogo
Instead of a wound up spring (as in some rechargeable torches and radios) to store the energy, a weight is used similarly as for counterwighted clocks....it's an old technology given a new twist.
Light output is adjustable from gentle glow to work light. and "charge" last from 30-18 minutes accordingly. Video shows what appears to be a vt AA battery sized flashlight hooked up for use as a reading light. No battery in the unit. Limited use, but would have value in an attic, shed, or short time location.
Since he's running a LED, I wonder if a super capacitor couldn't be charged at the same time that the weight is falling. When the weight reaches the floor, the LED could then continue to draw current from the super cap thereby extending the run time.
There is no free energy. To charge a cap, would diminish the light output. At high output, it will drop in 18 minutes, at low output, 30 minute.
True. I was thinking along the lines of building one with enough capacity to do both. It would also require a little more weight. A 25 lb bag of #7 1/2 shot comes to mind.
