Perfect Light = Luxeon 3W (Or 5W) + Regulator + Hand Crank?

I was playing around with my Costco hand crank LED flashlight today. It has 3 LEDs which produce a decent amount of light for a few minutes (about 15 mins of light per 2 minutes of hand crank).

The light does not have much throw, and the light has a strong blue tinge, but it makes a good emergency light.

I've fallen in love with handcranks because the benefit of never needing batteries far outweighs the pain of cranking the flashlight every few minutes.

So, this combination would be perfect:

3W Luxeon LED (bright light with good throw)
Regulator (to keep the light output at a constant brightness)
Hand crank (never need batteries)

Give me such a light and I will be a coon in a cabbage patch.

I hope there is no technical hurdle to be crossed in building such a light!

Let's do the math... a 5mm LED is lets say 25ma (slight overdrive) at 3.5v which equals 0.0875 watts.... multiply that by 3 and you get 0.2625 watts running for lets say 10 mins at such brightness average you get 2.625 watt/minutes so a 3 watt LED would run for less than a minute per two minutes of cranking... perhaps 30 seconds would be my guess and dimming the entire time to nothing.

fade2black said:

... (about 15 mins of light per 2 minutes of hand crank).
.....3W Luxeon LED

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(second try, first lengthy reply disappeared in net nirwana)

Lets assume you want to have a 3W or 5W LED to use it at the rated power (why else). The generator setup with regulator, mechanics and energy storage will be below 50% (and this number is already very optimistic). For that ration of 1:8 in between winding up and burntime you will end up at ~50W mechanical input power (or 80W for the 5W LED).
I doubt if you will have much fun with that....
Besides that a 30W generator will not be that small and light.

We discuss generator lights since decades among cavers. Still several people think, it is somewhat an infinite light source. Beside other shortcomings as a caving backup light, I did a simple calculation:

A good Lithium D cell has around 50Wh at low output and more than 20 years of useful shelf time when not stored too hot. And similar size and weight as a dynamo setup.

The hand driven generators I know are all in the 200mW range, (maybe some at 0.5W). That means that a D cell could give 250 hours of 200mW.
I'm very shure that all of these dynamos will not survive more than a few hours of actual use. Actually I've seen many of them failing at less than one hour generator using time.

Of course a dynamo light has the benefit that you can not run it down in the case you forgot to switch it off. A switch which has to be activated every few minutes for a battery light could do (almost) the same.
And it will work even after beeing stored for a longer time at higher temperature.
But I have seen dynamo lights not working after some time beeing stored and the generator was completely rusty, temp changes may have caused it.
And a dynamo light is much more difficult to make waterproof.
We had some of them failing after only a little bit of sand came into the gearbox.

Back in the seventies, Russian emigrants sold some of their belogings at a flea market in Vienna to get western currency. I remember that I have seen very well looking full metal dynamo lights. Unfortunately I did not buy any back then.

All together, all the dynamo ligths I have seen so far could not ven come close to the 'eternal light' myth. And I doubt if it is even possible, affordable or not.

Pelu and Lynx thanks for your posts.

I'm an ignoramus when it comes to the math and technical details, but I definitely see two trends -

1. We are seeing brighter LEDs at low power consumption.

2. Hand cranked lights are gaining popularity as an infinite light source.

Maybe not a 3W or a 5W, but a bright 1W hand cranked LED light with a reasonable run time should become a reality in a not too distant future.

Even with the more efficient small LEDs that are coming out, you will not approach the brightness of a Luxeon with something that you can crank without getting tired.

The problem with many of these dynamo lights is that they have a small NiCD or NiMH battery inside. That battery will fail to hold a charge after a few years, whether you use the light or not. (Some lights have a capacitor instead. I'm not sure how those hold up.)

For the light output, cost, and life of these lights, you'd be better off putting your money towards a small and cheap LED light and some batteries. Alkalines have a shelf life of >5 years, and lithiums >10 years. Or, you could get a small solar battery charger.

http://www.lighthound.com/ has some nice small LED lights at low prices. There's also the Dorcy 1AAA and 1AA, and Inova lights.

fade2black said:

I definitely see two trends -

1. We are seeing brighter LEDs at low power consumption.

2. Hand cranked lights are gaining popularity as an infinite light source.

Click to expand...

For the simple reason we are flooded with cheap and inexpensive gadgets from the far east. Most of thgese lights were around for some time.

Yes, you are right, they are gaining popularity as an 'infinite' light source. But this is a myth. Anyway, myths are always good for marketing.

LEDs may increase their efficiency by a factor of 3 until they come to some limit. Thats it. Primary cells will also become better in performance, capacity, self discharge, shelf life and price.
Generators and gear boxes will not get better in the same range.

Maybe not a 3W or a 5W, but a bright 1W hand cranked LED light with a reasonable run time should become a reality in a not too distant future.

Click to expand...

According to my (already too optimistic) guestimations, you will end up at ~20W of mechanical input power (but only when well designed and manufactured, that means no cheap light), which is way too much for practical use.

And, of course, the energy storage. The lights which use tiny NiXX batteries (some have a 70mAh memory backup battery) will fail after some time of storage if one of the cells short internally.
The other ones with supercaps inside may last longer (charge cycles wise), but they cannot store very much energy.

Some people might buy it because they are tired to have a torch/flashlight's batteries empty when they need it once a year. They will store it in a drawer and take it out one time. Some of these dynamo light will work then, other will not .-) If people would have bought just a couple of keychain lights like the cheap Photon clones, it is more likely that they have useable light when they need it.
But according to my observations, most of this lights are bought as a child's toy (sometimes for big childs .-) and they work fine for keeping them busy.

Look at this lights as toys, not as tools.

Thirty years later

http://www.tv-master.ru/house/1-32.htm

The author notes that the light is "blindingly bright" and is a lot easier to crank than the incandescent.

maybe a 5 watt Luxeon driven on a bicycle dynamo? Is there any such lights made yet?:huh:??

PeLu said:

LEDs may increase their efficiency by a factor of 3 until they come to some limit.

Click to expand...

How do you figure?

balazer said:

How do you figure?

Click to expand...

What else? nowadays most optimistic data comes to ~60lm/W, theoretical limit is at some 200lm/W (for white light, always assuming white light).
If you want, take a 4 times increase, does not really change much.
Sorry, no wonders.

A bicycle dynamo might put out 10-15W (depending on the RPM) at some 150g. Best efficiency is around 70%. Very good geering will have 85-90% for this needed ratios.

This Russian dynamo lamp (posted above) was originally made for a 3.7V 0.07A incandescent bulb. It might put out 150mA peak. Does not really run a Luxeon at high power.
The light is easier to start as with an incandescent, as the incandescent has a very low resistance when unlit, while the LED behaves in an opposite way. At least as long as the capacitors have some charge left (which they will).

The best LEDs may be around 60 lumens/watt near their optimal current, but most LEDs are not, and certainly not the brightest LEDs. There's a lot of room for improvement.

fade2black said:

Maybe not a 3W or a 5W, but a bright 1W hand cranked LED light with a reasonable run time should become a reality in a not too distant future.

Click to expand...

Well, look at what we have here! A 1-watt Luxeon Freeplay flashlight!

http://www.ccrane.com/lights/led-flashlights/freeplay-jonta-flashlight.aspx

I wonder about this... on a bit larger scale, couldn't one build a box approx double the size of a normal 6V lantern that holds a SLA battery, a 1W lux regulated at about 400-500 mA with a crank that was about 6" long for a diameter of crank of 12"? Have flush-mounted bezel containing a reflector designed for a fairly wide angle beam?

My LED_ASAP modded ARC AAA is at 400 mA and in total darkness, can easily let two or three people read at the same time... don't know why it couldn't be done on a larger and rechargeable scale.

Target's been getting some really cool lights lately.

what do you think about the SHAKE-N-LIGHT FLASHLIGHT?

If you want lose your money buy one, a look that flashlight in a store and a shake like for 20 minutes looking for more light and never come... jajajja realy, dont buy...

I would like to thank fade2black for starting this thread. I find this topic interesting. I'm pasting one of my replies from another thread below.

I remember seeing these at Target when buying a RR lantern. I checked them out but wasn't impressed. I think the concept has merit in the niche of emergency flashlights, but I've yet to see a rendition that has been good enough to open my wallet.

I hope this isn't too off-topic, but when seeing mention of lights like this it makes me wish for something in the form factor of a cut-down 1D M@g. It would have a crank-style generator in the tube that charges some type of Li-ion cell. Something custom built with a retractable or folding crank powering a white Luxeon I.

The shake-lights are usually pretty weak in terms of output, and I would like to see one with a SERIOUS generator in there. A geared-up mechanism would make the crank hard to turn; but then it would actually be able to produce enough power to be useful. I've seen crank-powered Nichia based lights that looked much better to me than the shake-powered style, but again the output was lacking. Nor did they look very durable.

Unfortunately, I don't have time to dive into building something like this; which is frustrating because I'm certain it's a viable idea.

The shake light seems a good choice to pass out to native's in third world countries w/o electricity. Being in a first world country, I can't see much use for it, except figity children and people who never maintain their stuff.