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# LED light from wind turbine Answered

We are playing around with various basic LED lighting from a small wind turbine and have a couple different ideas about how to build.  But we are wondering what the voltage range LED lighting can handle?  Even a small turbine can create a wide range of wattage based on the speed of the wind, at what point are we going to be doing damage to our lighting?  Do we need to come up with some sort of wattage dampener/regulator between the generator and the lights?  Simplicity is key in our design.

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Do it the simple way for the sake of your insanity ;)
Check the output of the generator in question under low wind conditions.
This output voltage is you minimum, let's say it would be around 4V.
Do the same again with the wind limit for your turbine / fan construction - you can simulate with a speed regulated drill if you have to.
Let's say under full wind you get a bit over 20V.
For this I would connect a 5V step down converter to the generator and wire the resistors for the LED's to match the 5V.

Of course it all depends on what your wind turbine is capable of in terms of revs per minute and torque that can be converted.
If your output is lower than 12V it might be easier to just use an adjustable voltage regulator and big capacitor to fix the output to 4V and use LED resistors for that.
For 12V output, for example to use LED strips, use a 12V regulator (LM7812) and a big capacitor to cater for light wind changes.

Thanks, I think I mostly follow your ideas, but this is a little out of my comfort zone. I will use the drill to simulate wind speed, measure voltage and see what happens and go from there.

LEDs have an extremely low tolerance for voltage swings, so they should always be current controlled. Further different colors have different voltage drops - excluding IR LEDS (which emits very little visible light, or none at all,, depending on the wavelength and the eyes looking), the voltage can be from ~1.8V to around 3.6V, depending on color and chemical compound.

A Constant Current Drain will probably be the least intimidating solution, as long as efficiency isn't an important parameter - 2 resistors and 2 transistors is what it takes. You still need to know the max. voltage though, to select a transistor that can handle the power it will have to dissipate.

I can make you a schematic, simple to put together, but to calculate the appropriate components, I'll need to know max. voltage of the gennie and how many LEDs of which color that you plan to feed.

If efficiency IS important, things gets more hairy, as a current mode switcher is a bit more involved.

The simple solution, I could teach anyones grandma in less than a week, sort of speaking, so if that will work for you, you could be less than a week from the solution :)

This is a bit of a folly, I'm pushing myself out of my comfort zone and I hope I will actually learn something here as I develop this. I have one turbine now and another one on order so I will have to figure out how much juice they create as a first step. I tested my 12v LED on a 9V battery and it worked, are there guidelines for what range of voltage is best? If I'm not matching up correct voltage am I shortening the life of the LED, or what is the downside? Will it just not work?

As long as the voltage is UNDER the rated voltage for the LED there is no problem.

But if you go over the limit the LED's usually won't have a long lifespan.
I have a red, ultra bright LED in a little projection clock and I wired it so te LED is about 30% under the max load - working non stop now for over 6 years.
Best option if the generator does not have a regulator already is to use step down converter or on the slightly more expnsive side a step up/down converter.
The later will for example supply a fixed 5V voltage from an input between 3 and 24V.
Usually it is easier and cheaper to just use a step down converter with a wide input range.

If your thinking LED downlights or LED ribbons you can get 12 volt ones , which are perfect for a 12 volt battery, and then get your turbine to charge the battery via a cheap solar regulator.

Wow, I guess I have not priced these out for awhile, I'm surprised they are so cheap. After I establish how much power these turbines put out I will look into sizing one of these.