Bicycle generators and LED lights

[Ignoramus16112]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

I want to do it in some nice way, such that

1) the LEDs would work across the range of speeds and be protected
from overvoltages and such

2) Most power would not be lost on some current limiting resistors,
but instead would go into LEDs. I think that 6W spent on LEDs would
give me a lot of light.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

I would prefer LEDs to regular incandescent bulbs for many very
obvious reasons (more light and more reliability).

I am moderately handy and built some electronic things before, like a
control and inverter for a DC welder.

Any ideas?

i

 

[Tim Wescott]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

I want to do it in some nice way, such that

1) the LEDs would work across the range of speeds and be protected
from overvoltages and such

2) Most power would not be lost on some current limiting resistors,
but instead would go into LEDs. I think that 6W spent on LEDs would
give me a lot of light.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

I would prefer LEDs to regular incandescent bulbs for many very
obvious reasons (more light and more reliability).

I am moderately handy and built some electronic things before, like a
control and inverter for a DC welder.

Any ideas?

i

Try your local bike shop?

Back when I rode all the time _the_ mail-order bike place was Bike
Nashbar -- I believe they still have a website, and that it's still
pretty good. You could also try the REI website (or check if there's an
REI near you).

The bees knees would be a Sturmey-Archer dynohub with a switching
converter powering the lights, but (a) you'd have to import the hub
yourself, (b) you'd have to have a wheel laced with the hub, and (c)
you'd have to build the converter.

For anything that involves a generator working against a wheel, you're
probably much better off to use LEDs powered by a set of Lithium Polymer
batteries.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[Ignoramus16112]

Try your local bike shop?

Yes, I visited a local shop, they did not have generator lights. What
they had was battery powered rechargeable lights with proprietary
batteries.

Back when I rode all the time _the_ mail-order bike place was Bike
Nashbar -- I believe they still have a website, and that it's still
pretty good. You could also try the REI website (or check if there's an
REI near you).

The bees knees would be a Sturmey-Archer dynohub with a switching
converter powering the lights, but (a) you'd have to import the hub
yourself, (b) you'd have to have a wheel laced with the hub, and (c)
you'd have to build the converter.

For anything that involves a generator working against a wheel, you're
probably much better off to use LEDs powered by a set of Lithium Polymer
batteries.

Maybe you are right, but I would like to hear some justification of
that.

i

 

[Jim Yanik]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

I want to do it in some nice way, such that

1) the LEDs would work across the range of speeds and be protected
from overvoltages and such

2) Most power would not be lost on some current limiting resistors,
but instead would go into LEDs. I think that 6W spent on LEDs would
give me a lot of light.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

I would prefer LEDs to regular incandescent bulbs for many very
obvious reasons (more light and more reliability).

I am moderately handy and built some electronic things before, like a
control and inverter for a DC welder.

Any ideas?

i

I saw a 3W LED replacement bulb for 2,3,or 4 cell Maglite flashlights,in
Wal-Mart,selling for $19 USD. (different bulbs for 2,3,or 4 cell use)

 

[[email protected]]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

On the contrary, almost all bike generators are 6 volts, 3 watts.
(That's half an amp.)

Voltage does vary with speed, but these days most generators are
well-designed to self-regulate to a max of about 6.5 volts. However,
that's assuming that a standard generator headlight bulb (or headlight
& taillight) are fitted.

Generators are pretty much constant current devices. If a generator
sees more resistance, it still tries its best to pump out half an amp.
It does that by producing more voltage. It's not hard to get over 30
volts out of many generators, if the load has high resistance - like,
for example, an open circuit.

I want to do it in some nice way, such that

1) the LEDs would work across the range of speeds and be protected
from overvoltages and such

2) Most power would not be lost on some current limiting resistors,
but instead would go into LEDs. I think that 6W spent on LEDs would
give me a lot of light.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

I would prefer LEDs to regular incandescent bulbs for many very
obvious reasons (more light and more reliability).

I am moderately handy and built some electronic things before, like a
control and inverter for a DC welder.

Any ideas?

First, recall that bike generators are AC devices. LEDs are DC.

Red LEDs are much more efficient than incandescent bulbs trying to
shine through red plastic lenses, so you could easily gain efficiency
in an LED generator taillight. But it's so easy to clip on a battery
powered LED blinky that the generator version is probably not worth the
trouble.

I think we're just now at the point in time where white LEDs are
significantly more efficient than halogen bulbs. (And that's not all
white LEDs, but the much more expensive Luxeon creations.) But it
requires some serious work to take advantage of that.

The biggest obstacle, I think, is optics. Generator lamps often have
excellent, excellent optics, so every lumen goes to a useful place.
LEDs put out a fuzzy cone of light, more or less. You want the former.

I once found an article in German where someone had taken a 3 watt
Luxeon and found a way to graft it into a commercial bike headlamp
unit. IIRC, they needed a big aluminum plate for a heat sink, and they
ended up with the LED facing _up_ at the bulb's focus point, slicing
the headlamp nearly in half.

Unfortunately, I don't read German; and I'm away from my bookmarks.
But that's what I recall.

If you can contact Andreas Oehler (sp?) he can give you all the info
you could possibly use. He drops in here occasionally when the talk
turns to generators.

- Frank Krygowski

 

[[email protected]]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

I want to do it in some nice way, such that

1) the LEDs would work across the range of speeds and be protected
from overvoltages and such

2) Most power would not be lost on some current limiting resistors,
but instead would go into LEDs. I think that 6W spent on LEDs would
give me a lot of light.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

I would prefer LEDs to regular incandescent bulbs for many very
obvious reasons (more light and more reliability).

I am moderately handy and built some electronic things before, like a
control and inverter for a DC welder.

Any ideas?

i

Go to Peter White Cycles website and look in the lighting section. He
sells a generator driven LED. There is another brand from England he
does not sell. I don't recall if he mentions the other brand in his
articles or not. The other brand was in a thread on this forum some
time ago. Do a Google search on rec.bicycles.tech.

As for LED being preferred over incandescent, no. The only advantage
LED has is in battery life and bulb life. Since you are using a
generator, battery life is not a consideration. As for bulb life,
incandescents are usually $3 each. They run for many, many hours.

 

[Tim Wescott]

Yes, I visited a local shop, they did not have generator lights. What
they had was battery powered rechargeable lights with proprietary
batteries.




Maybe you are right, but I would like to hear some justification of
that.

i

There are three ways of coupling the generator to the bike's motion that
I've seen in practice:

1. A toothed wheel that runs on the tire sidewall. These are very draggy.

2. A generator inside a wheel that runs on the tire tread. These are
much lower drag than (1), but the ones I've seen mount on the
intersection of the chain stays with the bottom bracket, and they don't
last long. They're also not easy to come by.

3. The Sturmey-Archer dyno hub. I haven't personally used it, but it
puts the generator inside the front hub of the wheel. I have a close
cousin and friend who _does_ have experience with them, and he speaks
highly of them. They're hard to get in the US (if S-A even makes them
any more). It's supposed to be very reliable -- the construction
certainly _sounds_ bullet proof -- but there's a bit of a weight penalty.

All of these methods suffer from the simple problem that when you stop
the light goes out. So you have your choice of inefficient, more
efficient but hard to get and breaks, or quite efficient but heavy and
unobtainable.

On the other hand batteries enjoy fairly good reliability, availability,
and longevity. What's more, they don't drag on the bike _at all_ and
you stay visible at intersections, which is where you most want to be seen.

The best of both worlds would be a generator-powered charge controller
and battery management system that charges a small battery pack to keep
the lights up when you're stopped. With care this could give you a
really nice system, but there's a big potential to buy yourself the
worst of all possible worlds. Don't rule it out, but count on lots of
work getting it working (and when you do get it going I'll buy one).

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[GregS]

On the contrary, almost all bike generators are 6 volts, 3 watts.
(That's half an amp.)

How about mounting several of those LED light generators that you shake back and forth.
You can also put one under the seat so you can bounce up and down. Anytime the bike hits
a bump your good to go.

greg

 

[John Woodgate]

The best of both worlds would be a generator-powered charge controller
and battery management system that charges a small battery pack to keep
the lights up when you're stopped.

Raleigh bicycles (who owned Sturmey-Archer) had this system on some of
their products in the 1950s, but there were no rechargeable cells cheap
enough in those days, so there was just a (selenium, probably) rectifier
to isolate the battery from the lamps when the dynohub was generating.

 

[Luhan]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

I want to do it in some nice way, such that

1) the LEDs would work across the range of speeds and be protected
from overvoltages and such

2) Most power would not be lost on some current limiting resistors,
but instead would go into LEDs. I think that 6W spent on LEDs would
give me a lot of light.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

I would prefer LEDs to regular incandescent bulbs for many very
obvious reasons (more light and more reliability).

I am moderately handy and built some electronic things before, like a
control and inverter for a DC welder.

Any ideas?

i

I have a 6 volt, 4 amp hour gel cell on my bike along with a set of 8,
125,000 mcd white LEDs. The total draw is about 200ma, and I only need
to rechage the battery once a month.

Luhan

 

[Nigel Cliffe]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

Most are 6v and 3W. They generate the 3W from a very low speed. This is
because of a German specification for generator performance on bicycles, and
Germany is a huge market for such devices, so pretty much everyone supplying
Europe makes stuff to the German specification.
The convention is to run either a single 3W front lamp, or a 2.4W front and
0.6W rear in parallel (thus creating a 3W load).

The drag and power output of generators varies. To a large extent, you pay
more for lower drag and higher efficiency.

If it's a tyre generator, then the tyres need to have side-walls which are
strong enough to take the wear. Modern thin "skin wall" tyres found on many
race bikes are not really suited. Modern touring tyres are usually fine.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

Look at the Busch and Muller website for one supplier. They have LED front
and rear lamps, as well as conventional bulb options.
http://www.bumm.de/index-e.html

I think Peter White in the US may import some B&M lamps or some similar
items. He also has the expensive (superb) Schmidt SON generator hub. Not
sure if he does the "half the price and almost as good" Shimano alternative
one (Shimano make several, their top model is the good one).

An expensive, but clever, LED front light (the 1203D) is available from
SolidLights in the UK. Designed for use with a hub generator, though should
work with side-wall generators. It should be compared with the twin E-6
lamp setup often used by hub dynamos.
http://www.solidlights.co.uk/


I think the LightSpin generator has an option to include a re-charging
circuit which keeps the lamp on full power for a short time when stopped.
(If you can't read / translate from Swiss-German, then google for other
pages on their products)
http://www.lightspin.ch/


I think Sheldon Brown has pages on generator driven lamps.



I have B&M lamps on a couple of my bikes.
The tail lamps are LED, the fronts are conventional bulb. Both front and
rear have "stand lights", so stay illuminated when stationary for a few
minutes (front illuminated with single LED marker lamp, not glowing your
route).
I have two different generators: the newer one is a Shimano hub built into a
wheel for winter use on my better tourer, and a B&M Dymaotec-6 side-wall
generator for my hack bike; cheap enough to not worry about it, and
sufficient quality for a 4 mile commuting ride.


- Nigel

 

[Ignoramus16112]

Nigel and others, thanks a lot.

My enthusiasm for making something of this sort became quite tempered
by the simple fact that I cannot possibly make the optical part of it
(making sure that LEDs are located in a near perfect spot of a near
perfect reflector) nearly good enough.

So it boils down to either buying a ready product, and they seem to be
too expensive, or just going with a cheaper light that takes four
rechargeable AA batteries.

As my use of the bycicle includes commute to a train station, I am
averse to buying very expensive components.

So, I decided to go with a cheaper 4AA light and bought an item
similar to this in all respects:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160012194668

I hope that it provides enough illumination, but if not, the loss is
not huge. I will rarely run in complete darkness, I hope.

i

 

[Nigel Cliffe]

Nigel and others, thanks a lot.

My enthusiasm for making something of this sort became quite tempered
by the simple fact that I cannot possibly make the optical part of it
(making sure that LEDs are located in a near perfect spot of a near
perfect reflector) nearly good enough.

So it boils down to either buying a ready product, and they seem to be
too expensive, or just going with a cheaper light that takes four
rechargeable AA batteries.

The current issue of the Audax UK magazine (*) has an article on AA battery
performance in cycle lights.
The conclusion was that NiMH rechargeables of 2700mAh were best
performance/price option, and some no-brand names were as good as branded
items costing three or four times as much.
The NiMH cells kept the test-lamp running at "usable" brightness much longer
than disposable AA's (Duracell), and nearly as good as much more expensive
Lithium cells.

Keep NiMH cells charged regularly, as they can discharge whilst standing
still. Turn off the lamp as soon as the output dims significantly to avoid
damaging the cells (ie. don't run them down to totally dead).


(* Audax UK is a club for very long distance cycle riding. Many Audax riders
ride long distances at night, some events require through the night stages,
so interest in effective lighting systems is high. )

As my use of the bycicle includes commute to a train station, I am
averse to buying very expensive components.

I can understand that, though my choice for my bike which is left at station
was a modest price generator and lamps on the grounds that they are bolted
to the bike and always ready to turn on.

If you don't mind carrying the battery lamps with you, and can keep the
batteries charged up, they are effective.


- Nigel

 

[Nate Knutson]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

I assume that output voltage of these generators varies with
speed. There are some on sale on ebay for not too much, 6v or 12v
models, most are 6 watts.

I want to do it in some nice way, such that

1) the LEDs would work across the range of speeds and be protected
from overvoltages and such

2) Most power would not be lost on some current limiting resistors,
but instead would go into LEDs. I think that 6W spent on LEDs would
give me a lot of light.

If there are products like that on the market already, I do not want
to "reinvent the wheel" and I would rather buy one, but I am not sure
if such a thing is available.

I would prefer LEDs to regular incandescent bulbs for many very
obvious reasons (more light and more reliability).

I am moderately handy and built some electronic things before, like a
control and inverter for a DC welder.

Any ideas?

i

A good place to start getting familiar with generator stuff is peter
white cycle's home page, I think peterwhitecycles.com. The
generator-powered LED he sells are Inoled, one of the few brands
currently available.

I recently set up an Inoled 20+ on a bike I built up for a friend, and
we've done a fair amount of riding side by side together. We both have
Schmidt hubs and my lights are a dual E6 setup. The Inoled is cheaper,
not as well designed (it has a design issue where it's rubber switch
button cover can get pushed into the body of the light, and it
generally doesn't fit very well - how good of a job it's doing at
keeping water out is yet to be seen, but it's probably fine). The
amount of light it puts out is pretty good and usable, but less than
the E6's by a fair amount. E6's are still quite a bit better for going
fast in the dark. Not having to replace bulbs is pretty nice, but it's
not a major issue on halogen lights either. However, one thing that the
Inoled does that halogens can't match is reach full brightness at low
speeds. Peter White's site says it's full brightness at 4.5 miles an
hour, compared to like 11 for the dual E6's. Also, it has a standlight
that's perfectly functional for reading maps or being seen while you're
stopped.

 

[Jim Yanik]

[email protected] (GregS) wrote in

How about mounting several of those LED light generators that you
shake back and forth. You can also put one under the seat so you can
bounce up and down. Anytime the bike hits a bump your good to go.

greg

Those are GARBAGE.

 

[Jim Yanik]

I have a 6 volt, 4 amp hour gel cell on my bike along with a set of 8,
125,000 mcd white LEDs. The total draw is about 200ma, and I only need
to rechage the battery once a month.

Luhan

Do you have a part number and source for those 125K MCD LEDs?
Isn't that more than a Luxeon LED?

Their efficiency seems incredible.

 

[Spehro Pefhany]

[email protected] (GregS) wrote in


Those are GARBAGE.

There have been credible reports that some of them are *fakes* (the
generator part does nothing) and they just run off of primary cells
button cells for a while.


Best regards,
Spehro Pefhany

 

[bob prohaska's usenet account]

For my bike (nothing special, a nice simple road bike bought at a
garage sale) I would like to add a bicycle generator and LED lights.

Any ideas?

Well, you've already gotten quite a few

For generators, you might take a look at
http://www.yellowjersey.org/dynamos.html

For LED's, try
http://www.theledlight.com/starswith_optics.html
you'd presumably want white low dome stars with optics at $14.80 each

My own experiments are documented at
http://www.zefox.net/~bob/bicycle/
but [gasp] the schematic isn't up-to-date; there's now an LED taillight
as well. Drop me a note if you're interested and I'll try to fix the
diagram. No standlights, however. That's less than ideal.

The system used on my father's Breezer Uptown 8 is a remarkably nice
setup: good halogen headlight, LED standlights front and rear with a
Shimano hub dyanamo. Unfortunately it does not seem inexpensive to buy
the dynamo in the US, and the cost of lacing a wheel is not appealling
unless you need one for other reasons. Roller dynamos work and are both
cheap and easy.

Drop me a note or post any questions you might have.

bob prohaska

 

[Luhan]

Do you have a part number and source for those 125K MCD LEDs?
Isn't that more than a Luxeon LED?

Their efficiency seems incredible.

--
Jim Yanik
jyanik
at
kua.net

I got them on Ebay. 50 for 99 cents plus $18 'shipping'. Thats
basically 50 for $20. They are 10mm (big) and have a 10 degree angle,
which runs up the mcd spec. I also bought 50 UV LEDs for $10 plus free
shipping - they work great too.

Luhan

 

[Luhan]

Do you have a part number and source for those 125K MCD LEDs?
Isn't that more than a Luxeon LED?

Their efficiency seems incredible.

--
Jim Yanik
jyanik
at
kua.net

Here is the supplier...

http://stores.ebay.com/HKJE-Led-Lamp-Center

Luhan