Dynamo powered LED headlamp??

Hi All

Has anyone already invented one of these?

If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other manufacturers
do that for the dynamo powered headlamps? Naturally, since the LED consumes much less power, what
I'm after is more light, with the same dynamo . . .

Cheers,

Jose B. Ruivo

 

On Thu, 09 Jan 2003 20:27:01 GMT, [email protected] (Big Ben) wrote:

>Hi All
>
>Has anyone already invented one of these?
>
>If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other manufacturers
>do that for the dynamo powered headlamps? Naturally, since the LED consumes much less power, what
>I'm after is more light, with the same dynamo . . .
>
>Cheers,
>
>Jose B. Ruivo

Go to http://www.topica.com/lists/bikecurrent/read?start=5922&sort=d and search for LEd and dynamo.
There was a pretty complete discussion about this pretty recently.

BTW- Leds don't really offer more light per watt than halogens, thsi is just a popular
misconception.

Bob

 

Big Ben wrote:
> Hi All
>
> Has anyone already invented one of these?
>
> If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other
> manufacturers do that for the dynamo powered headlamps? Naturally, since the LED consumes much
> less power, what I'm after is more light, with the same dynamo . . .
>
> Cheers,
>
> Jose B. Ruivo

The main problem I can think of is that dynamos can only produce an AC current, which is no good for
LEDs. It is possible to build DC generators but they have to be a bit cunning. I always assumed bike
dynamos produce AC as its simplest, and bulbs will run off it no prob.

-Alex

 

On Fri, 10 Jan 2003 20:17:10 +0000 (UTC), Alex Graham <[email protected]> wrote:

>Big Ben wrote:
>> Hi All
>>
>> Has anyone already invented one of these?
>>
>> If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other
>> manufacturers do that for the dynamo powered headlamps? Naturally, since the LED consumes much
>> less power, what I'm after is more light, with the same dynamo . . .
>>
>> Cheers,
>>
>> Jose B. Ruivo
>
>The main problem I can think of is that dynamos can only produce an AC current, which is no good
>for LEDs. It is possible to build DC generators but they have to be a bit cunning. I always assumed
>bike dynamos produce AC as its simplest, and bulbs will run off it no prob.
>
>-Alex

Its no problem to include a rectifier circuit, to convert the AC to DC, inside the headlamp. Infact,
some dynamo headlamps must have rectifiers as they use LED backup lights - I am thinking of the
Lumotech Standlight.

However it looks from the previous posts that a white LED is not going to light up the road.

John "close but no cigar" Tomlinson Remove the singers of Spam before replying

 

In message <[email protected]>, Myra VanInwegen
<[email protected]> writes

<snip>

>[email protected] (Graham) wrote
>> If you had front and rear LED's powered by dynamo which were roughly as powerfull as conventional
>> dynamo lights. Surely this would need a much smaller and much lower drag dynamo than the type
>> needed to power conventional incandescent bulbs.
>
>As has been pointed out several times, white LEDs do not supply more light per watt than
>halogen bulbs.

That's true when running at their rated power, but at, say, half power, (lower speed) a white LED
will still emit white light at a reduced intensity whereas an incandescent lamp will glow a rather
useless orange. This is surely an advantage for dynamo systems.

High power LEDs are here, albeit rather expensive, but that will doubtless change...

http://www.lumileds.com/

Cheers
--
Keith Wootten

 

[email protected] (Graham) wrote
> If you had front and rear LED's powered by dynamo which were roughly as powerfull as conventional
> dynamo lights. Surely this would need a much smaller and much lower drag dynamo than the type
> needed to power conventional incandescent bulbs.

As has been pointed out several times, white LEDs do not supply more light per watt than
halogen bulbs.

> Also the lights could run off re-chargable batteries, and when the batteries were low, the dynamo
> could be used during daylight to re-charge batteries of the LED's and so eliminate the problem of
> lights going out when stopped. And as LED's last almost infinitely it would eliminate the risk of
> bulbs blowing and give almost infinite lighting.

The rest of your post suggests that you're not very up on modern dynamo technology. First of all, I
use a dynamo that never slips in the wet and has drag so low that I can't even feel it. It's a
fairly inexpensive (35 Great Britian Pounds when ordered from Germany) Shimano hub dynamo. Building
it into a wheel didn't cost anything as I build my own wheels... So the goal of having lower drag
for the same brightness of lighting is already met.

Second, if you get decent dynamo lamps, they don't go out when you stop. Busch & Mueller make front
halogen lights with a white LED backup (powered by a capacitor that charges as you ride and keeps
the LED going for about 5 mins) and the back light is already a red LED (with a capacitor to prove
backup for 5 mins) to take advantage of the fact that LEDs produce red light far more efficiently
than bulbs.

Third, dynamo bulbs last a very long time. Red LEDs of course never burn out, and my front bulb has
been going -- don't remember how long, at least a year, with quite a bit of use. So already a dynamo
setup gives almost infinite lighting.

Doesn't seem like there's much improvement to be made, at least not in the areas you were thinking
of improving. There is improvement to be made in making dynamo systems brighter. I eagerly await a
good 6W dynamo setup, which will double the lighting power you get with a 3W setup. There are
standards being established for 6W setups, it's just a matter of time before people start to make
really good systems that go with them.

-Myra

 

On Fri, 10 Jan 2003, John Tomlinson <[email protected]> wrote:
> On Fri, 10 Jan 2003 20:17:10 +0000 (UTC), Alex Graham <[email protected]> wrote:
>
> >The main problem I can think of is that dynamos can only produce an AC current, which is no good
> >for LEDs. It is possible to build DC generators but they have to be a bit cunning. I always
> >assumed bike dynamos produce AC as its simplest, and bulbs will run off it no prob.
>
> Its no problem to include a rectifier circuit, to convert the AC to DC, inside the headlamp.

Except that you'll drop two diodes worth of voltage in teh rectifier (assuming a full bridge), and
that's wasted power. Since rectifier diodes may drop a volt each, potentially it's getting on for a
third of the power you might be losing.

You can make an 'ideal' diode out of active components, but it'll add to the cost and consume some
power in its own right.

Better, I think, to use the LEDS as the diodes in teh bridge. I can't immediately see any problem
with connecting two LEDs in parallel oppositte polarity across the output of teh dynamo. Obviously
it's twice the cost of LEDs, but I can't think why it wouldn't work.

> Infact, some dynamo headlamps must have rectifiers as they use LED backup lights - I am thinking
> of the Lumotech Standlight.

They have nothing like the power output on standlight as when running.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

 

[email protected] (Myra VanInwegen) wrote in message
news:<[email protected]>...
> [email protected] (Graham) wrote
> > If you had front and rear LED's powered by dynamo which were roughly as powerfull as
> > conventional dynamo lights. Surely this would need a much smaller and much lower drag dynamo
> > than the type needed to power conventional incandescent bulbs.
>
> As has been pointed out several times, white LEDs do not supply more light per watt than
> halogen bulbs.
>
> > Also the lights could run off re-chargable batteries, and when the batteries were low, the
> > dynamo could be used during daylight to re-charge batteries of the LED's and so eliminate the
> > problem of lights going out when stopped. And as LED's last almost infinitely it would eliminate
> > the risk of bulbs blowing and give almost infinite lighting.
>
> The rest of your post suggests that you're not very up on modern dynamo technology. First of all,
> I use a dynamo that never slips in the wet and has drag so low that I can't even feel it. It's a
> fairly inexpensive (35 Great Britian Pounds when ordered from Germany) Shimano hub dynamo.
> Building it into a wheel didn't cost anything as I build my own wheels... So the goal of having
> lower drag for the same brightness of lighting is already met.
>
> Second, if you get decent dynamo lamps, they don't go out when you stop. Busch & Mueller make
> front halogen lights with a white LED backup (powered by a capacitor that charges as you ride and
> keeps the LED going for about 5 mins) and the back light is already a red LED (with a capacitor to
> prove backup for 5 mins) to take advantage of the fact that LEDs produce red light far more
> efficiently than bulbs.
>
> Third, dynamo bulbs last a very long time. Red LEDs of course never burn out, and my front bulb
> has been going -- don't remember how long, at least a year, with quite a bit of use. So already a
> dynamo setup gives almost infinite lighting.
>
> Doesn't seem like there's much improvement to be made, at least not in the areas you were thinking
> of improving. There is improvement to be made in making dynamo systems brighter. I eagerly await a
> good 6W dynamo setup, which will double the lighting power you get with a 3W setup. There are
> standards being established for 6W setups, it's just a matter of time before people start to make
> really good systems that go with them.
>
> -Myra
--------------------------------------------------------------------------------
Ok point taken so what you're saying is (and excuse my ignorance about electronics) that red LED's
are more efficient than incandescent bulbs but white ones are not, because the light has to be
filltered to make it white. So if thats the case would it not be possible to make a dynamo which had
a LED rear light and a incandescent front light. Therfore you could put more power through the front
light. or has this already been done?.

By the way I do use a dynamo (cheap bottle type) and the bulbs especially the rear ones only seem to
last a few months, I have tried fitting a voltage regulator but it dosent seem to make much
difference.

Graham

 

"Keith Wootten" <[email protected]> wrote in message news[email protected]...
> In message <[email protected]>, Myra VanInwegen
> <[email protected]> writes
>
> <snip>
>
> >[email protected] (Graham) wrote
> >> If you had front and rear LED's powered by dynamo which were roughly as powerfull as
> >> conventional dynamo lights. Surely this would need a much smaller and much lower drag dynamo
> >> than the type needed to power conventional incandescent bulbs.
> >
> >As has been pointed out several times, white LEDs do not supply more light per watt than
> >halogen bulbs.
>
> That's true when running at their rated power, but at, say, half power, (lower speed) a white LED
> will still emit white light at a reduced intensity whereas an incandescent lamp will glow a rather
> useless orange. This is surely an advantage for dynamo systems.

Dynamos are actually quite good at getting to full power at low speeds.

http://www.myra-simon.com/bike/dynotest.html has a graph of electrical output vs speed. You'll see
full power (3W) happens at around 15kph/10mph. At 10kph/6mph, they're still producing 2W. Below that
you're probably walking!

I regularly ride my bike at night up a hill which slows me to 7/8mph. My lighting system has the
rear light in series with the front, so it's worse at low speeds than it's supposed to be. But it
still works. (5 year old shimano NX-10).

cheers, clive

 

"Clive George" wrote in message
>
> 1) Just run the front light off the dynamo, and use a traditional battery powered rear LED. A very
> popular solution, particularly if the dynamo is
at
> the front. Use a 3W bulb rather than the normal 2.4W.
>
> 2) B+M do a LED dynamo taillight. Some of the extra goes into making it a standlight. Don't know
> if you could fit a 3W bulb with it though.
>
On 2 of my bikes I have b&m oval plus head lights, D-Toplight Plus (with standlight) and Schmidt
hub dynamos.

If you use wires with spade connectors and connect them from the live terminal of the oval plus
headlight to the live terminal of the D-Toplight Plus, you can use a 3w bulb in the oval plus
headlight. The D-Toplight plus uses an LED so (virtually) all of the power go to the front
headlight.

Michael Anderson

 

[email protected] (Big Ben) wrote
> If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other
> manufacturers do that for the dynamo powered headlamps?

Cateye haven't replaced their halogen bulbs by white LEDs. They have added lamps with white LEDs to
their halogen-bulb lineup. The white LED lamps put out about the same amount of light prt watt
consumed as halogen bulbs. They are very good as be-seen lights because their color attracts the eye
well, but they do not illuminate the road as well as halogen bulbs, simply because they produce
considerably less light! Dynamo powered lights light up the road far far better than LED-powered
lights. If you had a 3W LED lamp, it would be huge, as it takes alot of space for the optics
required to focus LEDs. And it wouldn't light up the road any better than a 3W halogen bulb, but it
would be super-visible, as it would have that eye-catching bluish white color.

If you want more light for less power, you need to go for a flourescent tube or a metal halide light
(I think it's called that) like in the Cateye Stadium light.

Incidentally, red LEDs are far more efficient than a bulb with a red filter, both because LEDs
product pure wavelength red light very efficiently, and because bulbs lose light when it's filtered.
This is why red rear LEDs have been the standard for quite some time, and why red LEDs are indeed
vastly more efficient than bulb rear lights.

-Myra

 

"Myra VanInwegen" <[email protected]> wrote in message
news:[email protected]...
> [email protected] (Big Ben) wrote
> > If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other
> > manufacturers do that for the dynamo powered headlamps?
> If you want more light for less power, you need to go for a flourescent tube or a metal halide
> light (I think it's called that) like in the Cateye Stadium light.
>
And just in case you do feel like going down that route, the lowest powered metal halide bulb
available is 10W and the optics required to focus a fluorescent tube would be prohibitively large.
Although it might be possible to do something clever to focus the fluorescent

> Incidentally, red LEDs are far more efficient than a bulb with a red filter, both because LEDs
> product pure wavelength red light very efficiently, and because bulbs lose light when it's
> filtered. This is why red rear LEDs have been the standard for quite some time, and why red LEDs
> are indeed vastly more efficient than bulb rear lights.

Conversely, white LEDs are only blue LEDs with a fluorescent part to turn the blue light into white,
and thus have some of the inefficiency that bulbs do on the back, when they (LEDs) go on the front.

A

 

"Myra VanInwegen" <[email protected]> wrote in message
news:[email protected]...

> If you had a 3W LED lamp, it would be huge, as it takes a lot of space for the optics required to
> focus LEDs.

Why is that? Because the high wattage lamp would have a lot of LEDs? Or super powerful LEDs would
need especially large optics?

The Cateye 6v 'EL200 with three LEDs focuses a beam very well onto the road (although it's not very
bright, of course) and its head is small. I think the innovative "Opticube" design helps keep the
size down. (The whole lamp is only so large to accommodate the batteries and make it convenient to
quick-clamp on bars).

BTW, for the poster who wanted a small AND bright front LED light to be seen by: It would be
possible to remove the front business bit from this Cateye light and wire it up to separate power
supply elsewhere on the bike. Well nifty!

~PB

 

In article <[email protected]>, pLime {remove_fruit}@biggs.tc says...
>
> "Myra VanInwegen" <[email protected]> wrote in message
> news:[email protected]...
>
> > If you had a 3W LED lamp, it would be huge, as it takes a lot of space for the optics required
> > to focus LEDs.
>
> Why is that? Because the high wattage lamp would have a lot of LEDs? Or super powerful LEDs would
> need especially large optics?
>
> The Cateye 6v 'EL200 with three LEDs focuses a beam very well onto the road (although it's not
> very bright, of course) and its head is small. I think the innovative "Opticube" design helps keep
> the size down. (The whole lamp is only so large to accommodate the batteries and make it
> convenient to quick-clamp on bars).

Compare this to the EL300, this has five LEDs and their surrounding opticubes and thus has a much
bigger head than the EL200 and EL110. It would be interesting to see a larger array, maybe dinner
plate sized, of these LEDs.

Colin

 

"Colin Blackburn" <[email protected]> wrote in message
news:[email protected]...

> Compare this to the EL300, this has five LEDs and their surrounding opticubes and thus has a much
> bigger head than the EL200 and EL110. It would be interesting to see a larger array, maybe dinner
> plate sized, of these LEDs.

Yes, I suppose I answered my own question. So the EL200 uses about the most powerful LEDs available?

~PB

 

[email protected] wrote in message news:<[email protected]>...
> On Thu, 09 Jan 2003 20:27:01 GMT, [email protected] (Big Ben) wrote:
>
> >Hi All
> >
> >Has anyone already invented one of these?
> >
> >If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other
> >manufacturers do that for the dynamo powered headlamps? Naturally, since the LED consumes much
> >less power, what I'm after is more light, with the same dynamo . . .
> >
> >Cheers,
> >
> >Jose B. Ruivo
>
>
> Go to http://www.topica.com/lists/bikecurrent/read?start=5922&sort=d and search for LEd and
> dynamo. There was a pretty complete discussion about this pretty recently.
>
> BTW- Leds don't really offer more light per watt than halogens, thsi is just a popular
> misconception.
>
> Bob
--------------------------------------------------------------------------------
If you had front and rear LED's powered by dynamo which were roughly as powerfull as conventional
dynamo lights. Surely this would need a much smaller and much lower drag dynamo than the type needed
to power conventional incandescent bulbs. Also the lights could run off re-chargable batteries, and
when the batteries were low, the dynamo could be used during daylight to re-charge batteries of the
LED's and so eliminate the problem of lights going out when stopped. And as LED's last almost
infinitely it would eliminate the risk of bulbs blowing and give almost infinite lighting.

What a great idea hey I aught to patent it. can anyone tell me a reason why it wouldent work?.

Graham.

 

"Graham" <[email protected]> wrote in message
news:[email protected]...
> [email protected] wrote in message
news:<[email protected]>...
> > On Thu, 09 Jan 2003 20:27:01 GMT, [email protected] (Big Ben) wrote:
> >
> > >Hi All
> > >
> > >Has anyone already invented one of these?
> > >
> > >If Cateye can replace their halogen bulbs by white LEDs in headlamps, why can't other
> > >manufacturers do that for the dynamo powered headlamps? Naturally, since the LED consumes much
> > >less power, what I'm after is more light, with the same dynamo . . .
> > >
> > >Cheers,
> > >
> > >Jose B. Ruivo
> >
> >
> > Go to http://www.topica.com/lists/bikecurrent/read?start=5922&sort=d and search for LEd and
> > dynamo. There was a pretty complete discussion about this pretty recently.
> >
> > BTW- Leds don't really offer more light per watt than halogens, thsi is just a popular
> > misconception.
> >
> > Bob
> --------------------------------------------------------------------------
------
> If you had front and rear LED's powered by dynamo which were roughly as powerfull as conventional
> dynamo lights. Surely this would need a much smaller and much lower drag dynamo than the type
> needed to power conventional incandescent bulbs. Also the lights could run off re-chargable
> batteries, and when the batteries were low, the dynamo could be used during daylight to re-charge
> batteries of the LED's and so eliminate the problem of lights going out when stopped. And as LED's
> last almost infinitely it would eliminate the risk of bulbs blowing and give almost infinite
> lighting.
>
> What a great idea hey I aught to patent it. can anyone tell me a reason why it wouldent work?.

For the reason you just quoted : White LED's don't offer more light per watt than halogens, so your
LED front would need as much electrical power as the conventional incandescent bulb, so your dynamo
isn't smaller/lower drag.

(works for the back though...)

cheers, clive

 

> would be interesting to see a larger array, maybe dinner plate sized, of these LEDs. Colin
http://theledlight.com/expedition.html Source for 14 and 19 LED flashlight. I use a 7 LED
http://www.billcotton.com/MY_rides.htm#LEDlight I plan to upgraded to the 19 LED flashlight, if no
other development is reported soon.. http://www.ccrane.com/ccexpedition.asp The 7 LED get 40 hours
on three C cells I modified my 7 LED unit to use AA cells and get about 20 hours.

--
// Bill Cotton: Latitude N40° 03.756' W75° 06.192' / / Phone 215 663-8363 Data 215 663-8364 //
[email protected] [email protected] // [email protected] [email protected] //
www.billcotton.com


"Colin Blackburn" <[email protected]> wrote in message
news:[email protected]t...
> In article <[email protected]>, pLime {remove_fruit}@biggs.tc says...
> >
> > "Myra VanInwegen" <[email protected]> wrote in message
> > news:[email protected]...
> >
> > > If you had a 3W LED lamp, it would be huge, as it takes a lot of space for the optics
> > > required to focus LEDs.
> >
> > Why is that? Because the high wattage lamp would have a lot of LEDs? Or super powerful LEDs
> > would need especially large optics?
> >
> > The Cateye 6v 'EL200 with three LEDs focuses a beam very well onto the road (although it's not
> > very bright, of course) and its head is small. I think the innovative "Opticube" design helps
> > keep the size down. (The whole lamp is only so large to accommodate the batteries and make it
> > convenient to quick-clamp on bars).
>
> Compare this to the EL300, this has five LEDs and their surrounding opticubes and thus has a much
> bigger head than the EL200 and EL110. It would be interesting to see a larger array, maybe dinner
> plate sized, of these LEDs.
>
> Colin

 

On Fri, 10 Jan 2003 08:20:14 -0500, "bcotton" <[email protected]> wrote:

>> would be interesting to see a larger array, maybe dinner plate sized, of these LEDs. Colin
>http://theledlight.com/expedition.html Source for 14 and 19 LED flashlight. I use a 7 LED
>http://www.billcotton.com/MY_rides.htm#LEDlight I plan to upgraded to the 19 LED flashlight, if no
>other development is reported soon.. http://www.ccrane.com/ccexpedition.asp The 7 LED get 40 hours
>on three C cells I modified my 7 LED unit to use AA cells and get about 20 hours.

Check out:

http://www.glow-bug.com/product.php?sku=93

There is a new generation white LED which is supposed to be "as bright as some halogen bulbs"

cu Bob Denton Gulf Stream International Delray Beach, Florida www.sinkthestink.com Manufacturers of
Sink the Stink

 

In article <[email protected]>, [email protected] says...
> > would be interesting to see a larger array, maybe dinner plate sized, of these LEDs. Colin
> http://theledlight.com/expedition.html Source for 14 and 19 LED flashlight. I use a 7 LED
> http://www.billcotton.com/MY_rides.htm#LEDlight I plan to upgraded to the 19 LED flashlight, if no
> other development is reported soon.. http://www.ccrane.com/ccexpedition.asp The 7 LED get 40 hours
> on three C cells I modified my 7 LED unit to use AA cells and get about 20 hours.

Thanks for those urls. I was thinking more of the LEDs with opticubes. These opticubes focus each
LED separately to provide a tight beam for a bicycle. It probably limits their use as a torch
(flashlight.)

Colin