LED Bike Headlight

B

browntimdc

Guest
Just finished throwing together a light for my e-bike today. I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings of 6 LEDs.
Each string has an LM317L to regulate current to approx. 22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

Tim
 
"browntimdc" <brownt@r*e*m*o*v*e*flash.net> wrote in message
news:Xns93DDB52EE5CE1tbflash@207.115.63.158...
Just finished throwing together a light for my e-bike today. I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings of 6 LEDs.
Each string has an LM317L to regulate current to approx. 22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

Tim
Click to expand...
Linear regulators may be quite lossy but its big enough battery guess.
Couple of things might interest you:

www.candlepowerforums.com if you wnat to wring the last out of batteries
these guys wil help.

and the bike current mailinglist, link escapes me at mo.

Adam
 
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
browntimdc <brownt@r*e*m*o*v*e*flash.net> wrote:

Just finished throwing together a light for my e-bike today. I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings of 6 LEDs.
Each string has an LM317L to regulate current to approx. 22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

Tim
Click to expand...
24V 8AH on a bicycle? That's nuts!

I hope it's not an expensive SLA. I've never had one of those survive
bicycle use for more than a few months. They'd become an open circuit
somewhere out in the middle of nowhere at night. I switched to NiMH
because they are lighter, cheaper, and much more reliable for 24 to 48
W/hr packs.
 
On Wed, 20 Aug 2003 23:57:53 GMT, the renowned Kevin McMurtrie
<mcmurtri@sonic.net> wrote:

In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
browntimdc <brownt@r*e*m*o*v*e*flash.net> wrote:

Just finished throwing together a light for my e-bike today. I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings of 6 LEDs.
Each string has an LM317L to regulate current to approx. 22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

Tim

24V 8AH on a bicycle? That's nuts!
Click to expand...
I presume there's an electric motor on there somewhere as well as the
LEDs. ;-)

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
In article <mcmurtri-25B5A5.16580220082003@typhoon.sonic.net>,
Kevin McMurtrie <mcmurtri@sonic.net> wrote:
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
browntimdc <brownt@r*e*m*o*v*e*flash.net> wrote:

Just finished throwing together a light for my e-bike today. I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings of 6 LEDs.
Each string has an LM317L to regulate current to approx. 22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

Tim

24V 8AH on a bicycle? That's nuts!

I hope it's not an expensive SLA. I've never had one of those survive
bicycle use for more than a few months. They'd become an open circuit
somewhere out in the middle of nowhere at night. I switched to NiMH
because they are lighter, cheaper, and much more reliable for 24 to 48
W/hr packs.
Click to expand...
I've used the same 12V 7AH SLA on my commuter bike for some years now.
No motor, just lots of light. Replaced a NiCd system. Of course, this is
used in fairly mild winters, temperatures usually not dropping much below
0degC.

-frank
--
 
Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote in message news:<MPG.19ae643e7a04db35989c15@news.inreach.net>...
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
brownt@r*e*m*o*v*e*flash.net mentioned...
Just finished throwing together a light for my e-bike today. I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings of 6 LEDs.
Each string has an LM317L to regulate current to approx. 22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

The common white LEDs are rated at 3.6V, max 4VDC. At 3.6V times 6,
that's 21.6V, but if the LEDs approach 4V, that would be 24V. So
there is a good chance that the battery won't have enough voltage to
overcome the drops across the LEDs and regulator chip.
Click to expand...
I measured these at 3.3V @ 20mA. So, you're suggesting that the LED
forward drop will increase over time?

Tim
 
brownt@flash.net (Tim Brown) wrote in
news:bf7e12dd.0308211722.11b3e13f@posting.google.com:

Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote in message
news:<MPG.19ae643e7a04db35989c15@news.inreach.net>...
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
brownt@r*e*m*o*v*e*flash.net mentioned...
Just finished throwing together a light for my e-bike today. I used
18 of the 8000mcd white LEDs from lsdiodes.com. Three strings of 6
LEDs. Each string has an LM317L to regulate current to approx. 22mA
with a 56 ohm resistor. Reaches full brightness at approx. 22V. Run
off my 24V 8AH main battery. It's always lit when the bike is on:
DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

The common white LEDs are rated at 3.6V, max 4VDC. At 3.6V times 6,
that's 21.6V, but if the LEDs approach 4V, that would be 24V. So
there is a good chance that the battery won't have enough voltage to
overcome the drops across the LEDs and regulator chip.


I measured these at 3.3V @ 20mA. So, you're suggesting that the LED
forward drop will increase over time?

Tim
Click to expand...
No,there's a variation in LED Vf from LED to LED.
They all do not have the same Vf.Some will be 3.2Vf,some 3.9VF....

--
Jim Yanik,NRA member
remove null to contact me
 
In <bf7e12dd.0308211722.11b3e13f@posting.google.com>, Tim Brown wrote:
Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote in message
news:<MPG.19ae643e7a04db35989c15@news.inreach.net>...
Click to expand...

The common white LEDs are rated at 3.6V, max 4VDC. At 3.6V times 6,
that's 21.6V, but if the LEDs approach 4V, that would be 24V. So
there is a good chance that the battery won't have enough voltage to
overcome the drops across the LEDs and regulator chip.

I measured these at 3.3V @ 20mA. So, you're suggesting that the LED
forward drop will increase over time?
Click to expand...
I think these are lower-voltage-drop-than-average white LEDs. I do not
expect the voltage drop to increase with time.

- Don Klipstein (don@misty.com)
 
Jim Yanik <jyanik@nullkua.net> wrote in message news:<Xns93DEDC310E0F1jyanikkuanet@204.117.192.21>...
brownt@flash.net (Tim Brown) wrote in
news:bf7e12dd.0308211722.11b3e13f@posting.google.com:

Watson A.Name - 'Watt Sun' <alondra101@hotmail.com> wrote in message
news:<MPG.19ae643e7a04db35989c15@news.inreach.net>...
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
The common white LEDs are rated at 3.6V, max 4VDC. At 3.6V times 6,
that's 21.6V, but if the LEDs approach 4V, that would be 24V. So
there is a good chance that the battery won't have enough voltage to
overcome the drops across the LEDs and regulator chip.


I measured these at 3.3V @ 20mA. So, you're suggesting that the LED
forward drop will increase over time?

Tim


No,there's a variation in LED Vf from LED to LED.
They all do not have the same Vf.Some will be 3.2Vf,some 3.9VF....
Click to expand...
The point is I checked several LEDs, I checked each of my 3 strings
for total drop and the light works fine. I took Watson to mean that he
thinks I'll have trouble later. I'm well aware there is part to part
variation in voltage drop. If I were making a bunch of these lights
maybe I'd just use 5 lamps in a string or screen parts.

As it is I made a headlight for my electric bike and it works fine. I
thought I would just share the idea and a source of good, cheap LEDs.
I didn't come here to be challenged on every detail and lectured about
things I already understand. Good bye.

Tim
 
In article <slrnbke0ad.g46.don@manx.misty.com>, don@manx.misty.com
mentioned...
In <MPG.19b02d41a2955d12989c25@news.inreach.net>, Watson A.Name wrote:

The LED forward voltage varies with the individual LED. They give a
typical V, but they test for maximum, so it's possible that you may
get some LEDs in a batch that approach the 4V max. I've noticed that
the newer white LEDs that I got recently from Nichia are 0.1V to 0.2V
lower than the earlier ones, but I don't know if that's just a
difference between batches, or if it's that way with all. The usual
for the earlier ones was 3.5 to 3.6V. I've never noticed them change
to a higher value over time.

My experience is that better ones over the past 2 years had a voltage
drop averaging .1-.2 volt more than the voltage drop of older models
from 5-6 or so years ago. I remember back when an average Nichia white
or blue LED had a typical voltage drop of 3.4 or 3.5 volts.
Of course the light output doubled or more over these several years...
I remember Nichia's NSPW500BS having a typical "beam candlepower at 20 mA"
(my words) close to 2,000 mcd several years ago, and then it went to about
4,000 and then 5,600 and now it's 6,400...
But despite personally seeing long term positive correation between
voltage drop and efficiency for a given color and chemistry, I hear
enough about a negative correlation in that area in a short term.
Supposedly "duds" that also have unusual voltage drop further also have
unusually high resistance that makes unusual voltage drop being in the
upward direction. I see a few the other way, by being "duds" that have
partial shorts such as from static damage (mainly from static-sensitive
GaN and InGaN chemistries).

- Don Klipstein (don@misty.com)
Click to expand...
What seems strange to me is that Nichia hasn't changed their parts
numbering to show that improvement. And when I bought some recently,
they showed no indicator in the part number of what the rank is. The
original batch I got was rank S, the latest rank R. To me it would
seem best if the customer had a choice. Of course they would have to
charge more for higher ranks, but why not.

I noticed that some cheaper blue LEDs I got from Futurlec have dies
that aren't centered in the middle of the leadframe. Seems that if
you get a 'good price' on an LED, you're usually getting a second, not
a prime part.


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In <MPG.19b02d41a2955d12989c25@news.inreach.net>, Watson A.Name wrote:
The LED forward voltage varies with the individual LED. They give a
typical V, but they test for maximum, so it's possible that you may
get some LEDs in a batch that approach the 4V max. I've noticed that
the newer white LEDs that I got recently from Nichia are 0.1V to 0.2V
lower than the earlier ones, but I don't know if that's just a
difference between batches, or if it's that way with all. The usual
for the earlier ones was 3.5 to 3.6V. I've never noticed them change
to a higher value over time.
Click to expand...
My experience is that better ones over the past 2 years had a voltage
drop averaging .1-.2 volt more than the voltage drop of older models
from 5-6 or so years ago. I remember back when an average Nichia white
or blue LED had a typical voltage drop of 3.4 or 3.5 volts.
Of course the light output doubled or more over these several years...
I remember Nichia's NSPW500BS having a typical "beam candlepower at 20 mA"
(my words) close to 2,000 mcd several years ago, and then it went to about
4,000 and then 5,600 and now it's 6,400...
But despite personally seeing long term positive correation between
voltage drop and efficiency for a given color and chemistry, I hear
enough about a negative correlation in that area in a short term.
Supposedly "duds" that also have unusual voltage drop further also have
unusually high resistance that makes unusual voltage drop being in the
upward direction. I see a few the other way, by being "duds" that have
partial shorts such as from static damage (mainly from static-sensitive
GaN and InGaN chemistries).

- Don Klipstein (don@misty.com)
 
Tim Brown wrote:

The point is I checked several LEDs, I checked each of my 3 strings
for total drop and the light works fine. I took Watson to mean that he
thinks I'll have trouble later. I'm well aware there is part to part
variation in voltage drop. If I were making a bunch of these lights
maybe I'd just use 5 lamps in a string or screen parts.

As it is I made a headlight for my electric bike and it works fine. I
thought I would just share the idea and a source of good, cheap LEDs.
I didn't come here to be challenged on every detail and lectured about
things I already understand. Good bye.
Click to expand...
Actually, you missed the point, almost entirely. You posted an
interesting message on a subject that generated a pleasant discussion,
between people of varying levels of education, on this topic. That
indicates that it was a good topic for these groups. Very little of
the traffic was directly about or for you, but about other people
thinking (and, perhaps, making mistakes) and learning from your post
and the discussion generated by it. Your first paragraph, here is
also a good addition to that discussion.

Please don't go away mad. This thread is a good example of what this
group was created to do.

--
John Popelish
 
In article <MPG.19b0b6dff4719655989c2e@news.inreach.net>, Watson A.Name -
'Watt Sun' wrote:
What seems strange to me is that Nichia hasn't changed their parts
numbering to show that improvement.
Click to expand...
I have also noticed this.

And when I bought some recently,
they showed no indicator in the part number of what the rank is.
Click to expand...
Look for latter part of the lot number on the sticker/label on the
antistatic bag (if you actually got them from Nichia). The latter portion
of the lot number is a combined color and "beam-candlepower" brightness
ranking assigned to that lot.

The original batch I got was rank S, the latest rank R.
Click to expand...
For types that usually fall close to the border between ranks, you can
easily get some of the higher rank and then some of the lower rank. My
experience with many small quantity purchases for prototyping jobs is that
when you get shipped alternating-back-and-forth-rank LEDs, all of them
are not far from the border between ranks.

To me it would seem best if the customer had a choice. Of course they
would have to charge more for higher ranks, but why not.
Click to expand...
A lesser aspect of Japanese manufacturer culture?

I noticed that some cheaper blue LEDs I got from Futurlec have dies
that aren't centered in the middle of the leadframe. Seems that if
you get a 'good price' on an LED, you're usually getting a second, not
a prime part.
Click to expand...
Really badly noticeable such misalignment is not typically Japanese and
is arguably subpar from places other than Japan but near the "east coast"
of Asia.

- Don Klipstein (don@misty.com)
 
brownt@flash.net (Tim Brown) wrote:
Kevin McMurtrie <mcmurtri@sonic.net> wrote in message news:<mcmurtri-25B5A5.16580220082003@typhoon.sonic.net>...
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
browntimdc <brownt@r*e*m*o*v*e*flash.net> wrote:

Just finished throwing together a light for my e-bike today. I used 18



24V 8AH on a bicycle? That's nuts!

I hope it's not an expensive SLA.

It's a NiMH pack that drives a 400W motor.

http://home.flash.net/~brownt/electrobike.htm
Click to expand...

Cool!

In working with motors my experience is that they suck lots of current on
startup and can cause battery voltage to drop.
With the amount of regulation you are using; do you have any problems with
brightness change during accelaration?

Strill
 
Just out of curiosity, where did you get the carbon fiber
from?

Kevin McMurtrie wrote in message ...
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
browntimdc <brownt@r*e*m*o*v*e*flash.net> wrote:

Just finished throwing together a light for my e-bike today.
I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings
of 6 LEDs.
Each string has an LM317L to regulate current to approx.
22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run
off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

Tim

8cd is pretty good. I didn't know they'd reached that point
yet. They
were in the 1 - 2 cd range last time I played with them. At
that level
they were too expensive and too power hungry to be used as a
headlight.

I built a bike light using two 228mm CCFL tubes in the front
and a red
LED array in the back. The front lens is a mylar coated
parabolic
mirror made from carbon fiber. I'm in the middle of
switching ISPs so I
don't have a link for it at the moment. It draws about 620
mA total and
operates within 11 to 15 volts. Packs of 10 AA 2AH NiMH
cells power it.
A three way switch selects between headlight + tail, off, and
tail only.
A front panel green LED glows brightly when the light is off,
so I can
find the bike, and glows dimly as a battery indicator when
it's on.
Click to expand...
 
Tap Plastics <http://www.tapplastics.com/>

Tap Plastics is mostly a SF Bay Area business but they do web orders
too. They're always on my list of places to shop when gathering project
materials.


In article <bk6ioe$qc23e$1@ID-43450.news.uni-berlin.de>,
"Ron Hubbard" <hubbard_ron@hotmail.com> wrote:

Just out of curiosity, where did you get the carbon fiber
from?

Kevin McMurtrie wrote in message ...
In article <Xns93DDB52EE5CE1tbflash@207.115.63.158>,
browntimdc <brownt@r*e*m*o*v*e*flash.net> wrote:

Just finished throwing together a light for my e-bike today.
I used 18
of the 8000mcd white LEDs from lsdiodes.com. Three strings
of 6 LEDs.
Each string has an LM317L to regulate current to approx.
22mA with a 56
ohm resistor. Reaches full brightness at approx. 22V. Run
off my 24V 8AH
main battery. It's always lit when the bike is on: DRL.

Photo: http://home.flash.net/~brownt/jpg/PICT5094s.JPG

Tim

8cd is pretty good. I didn't know they'd reached that point
yet. They
were in the 1 - 2 cd range last time I played with them. At
that level
they were too expensive and too power hungry to be used as a
headlight.

I built a bike light using two 228mm CCFL tubes in the front
and a red
LED array in the back. The front lens is a mylar coated
parabolic
mirror made from carbon fiber. I'm in the middle of
switching ISPs so I
don't have a link for it at the moment. It draws about 620
mA total and
operates within 11 to 15 volts. Packs of 10 AA 2AH NiMH
cells power it.
A three way switch selects between headlight + tail, off, and
tail only.
A front panel green LED glows brightly when the light is off,
so I can
find the bike, and glows dimly as a battery indicator when
it's on.
Click to expand...
 
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