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Self-Solar Powered LED Flashlight?

I know it would not be 100% efficient, or even close for that matter. But I was wondering how much battery life could be "recycled" by directly projecting the light from the flashlight onto the solar panel(s)? Say at a 45 degree angle beneath the light.

Obviously this wouldn't be a high output LED, and another question at that.. Would a Red LED be more efficient or would the PV cell not do so well with Red LED?

Thought this would be a neat idea even if it would only recycle 5-10% battery life. I would love for someone to implement this idea into a project and see how efficient it is.



shawnnweed6 years ago
it's an interesting concept. However, it would take roughly sixteen 4" square solar cells(at 15% effieciency) to create 400 milliamps of current per hour. To run a high powered led takes a minimal of 350 milliamps to 700 milliamps. The red Led's would be little better because it's the infrared light that creates 80% of the current. However, the red led's do not go much past 700 nanometers with enough intensity to do what you are talking about and even the high power LED's in red require huge amounts of current(1500 milliamps). The best you can do is get a ten percent return and that is with using 98% of the light created. The best option for a long running light is to use the 'joule thief' with low powered led's. Love the idea though...working on something similar. If you would like to talk more...shawnnweed@yahoo.com.
nathan7234 years ago
A "self powered" system. Can but is unneeded. I would recommend doing a recharge system instead. Have the solar power recharge a power source(battery) then have the battery power the LEDs.
Should be fairly simple. And I know this is a little late. Lol
rickharris6 years ago
The advent of LEDS that can be turned off and on very quickly has change the concept of power saving. E.g. if you turn the led off for as much time as it is on you save half the power. If you do this faster than 25 times a second then your brain sees the light as on all the time.

It's called Pulse width modulation PWM
orksecurity6 years ago
Not even worth looking at. Any light you could (very inefficiently) convert back into electricity is light you were wasting. Better solution is to design the flashlight so it doesn't waste light, letting you reduce its power demands, and thus extend battery life.