"white" LED's vs. incandescent and halogen lights

On Dec 14, 3:37*pm, SMS wrote:

The loss of efficiency in rectification and regulation has been
explained here numerous times. I'm sure you can google it. Unlike
"darned bright" the loss of efficiency is an actual quantifiable number
based on the buck-boost regulator efficiency and the efficiency of a
full wave bridge rectifier.

And it's a number that just doesn't matter!

Again: People have successfully commuted for decades using halogen
headlamps powered by generators. People have successfully competed in
all-day-all-night audax rides using the same equipment. Its silly to
pretend that sort of system is inadequate for those uses.

Generator powered LED lamps have now reached the level where they are
better than halogen. They put out even more light with even less
effort. That's the sort of efficiency that matters.

I recall the generator test article at
http://www.myra-simon.com/bike/dynotest.html
mentioning that the drag caused by really good generator sets is
equivalent to climbing ten feet per mile or less. That's a good
illustration of "negligible." And since the forward voltage of a
typical LED is less than that of a halogen bulb, I'd expect even less
drag if those same generators are powering an LED.

So what if the system includes a full wave rectifier that slightly
reduces that efficiency? Drag is still going to be less than with the
halogen - that is, less than negligible. Your theoretical drop in
efficiency just does not matter in any practical way.

- Frank Krygowski

"Frank Krygowski" wrote in message
...

I recall the generator test article at
http://www.myra-simon.com/bike/dynotest.html
mentioning that the drag caused by really good generator sets is
equivalent to climbing ten feet per mile or less. That's a good
illustration of "negligible." And since the forward voltage of a
typical LED is less than that of a halogen bulb, I'd expect even less
drag if those same generators are powering an LED.

It'll be higher with the good lights - they draw up to 4W via clever
electronics. (because you can do that sort of thing with LEDs). See past
posts by Andreas Oehler.

On Dec 14, 1:48*pm, "Just zis Guy, you know?"
wrote:
On Mon, 14 Dec 2009 13:38:46 -0800 (PST), N8N
wrote:

34.99 (under 60 of your colonial dollars). I have one, it works
flawlessly and will comfortably power a B&M IQ Cyo which produces 60
Lux, which is five times the German legal required light output.
And that's how much with shipping?
34.99. *Free delivery.
To the YooEss? *I kinda doubt it... *Even Wiggle doesn't give free
shipping under about $80ish, and I can't see how they are making money
on orders at that level.

That's a UK site, I have no idea how much the same unit would cost
from a US shop but I can't recall ever having found any Japanese
manufactured item cheaper in the UK than in the US - usually it's very
much the other way around. Not to say it wouldn't happen, it would
just be unusual for it to be cheaper here than there.

Earlier this year the USD/GBP exchange rate was quite favorable to get
myself a Shimano 3n72 dynohub from Wiggle instead of in the US.

-pm

In ,
SMS tweaked the Babbage-Engine to tell us:
Actually you could get
by with the 3W headlight, but that leaves nothing for the tail light
unless you get a 12V/6W tire driven dynamo, which costs $325.

Or you could do what sensible people do and use a battery-powered LED rear
light, which, unlike a front light, will run for the best part of a
Randonneur Round The Year season on a pair of AAAs.

--
Dave Larrington
http://www.legslarry.beerdrinkers.co.uk
The System is well pleased with this Unit's performance, which
falls within expected parameters.

On Mon, 14 Dec 2009 12:37:55 -0800, SMS wrote:

The loss of efficiency in rectification and regulation has been
explained here numerous times. I'm sure you can google it. Unlike
"darned bright" the loss of efficiency is an actual quantifiable number
based on the buck-boost regulator efficiency and the efficiency of a
full wave bridge rectifier.

Then don't use a full wave bridge rectifier (there's no need for it),
and don't use a buck-boost regulator (there's no need for it).

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

Dave Larrington wrote:
In ,
SMS tweaked the Babbage-Engine to tell us:
Actually you could get
by with the 3W headlight, but that leaves nothing for the tail light
unless you get a 12V/6W tire driven dynamo, which costs $325.

Or you could do what sensible people do and use a battery-powered LED rear
light, which, unlike a front light, will run for the best part of a
Randonneur Round The Year season on a pair of AAAs.

No argument there, but someone in this thread was trying to find an LED
bulb for their rear dynamo powered light. The whole thing is ridiculous.
You want to not waste any of those 3 watts from the dynamo on a rear
"being seen" light. Especially because for a rear LED light you want one
with multiple LEDs, at least two of which are side pointing. Buy a
CatEye TD-LD1100 for $28 and be done with it.
"http://www.lickbike.com/productpage.aspx?PART_NUM_SUB=%273340-00%27"

On 15 Dec, 16:41, SMS wrote:
:
.. Especially because for a rear LED light you want one
with multiple LEDs, at least two of which are side pointing. Buy a
CatEye TD-LD1100 for $28 and be done with it.
"http://www.lickbike.com/productpage.aspx?PART_NUM_SUB=%273340-00%27"

Run it on 2900 mAh NiMHs and you are sorted.

--
Simon Mason

"SMS" wrote in message
...
Dave Larrington wrote:
In ,
SMS tweaked the Babbage-Engine to tell us:
Actually you could get
by with the 3W headlight, but that leaves nothing for the tail light
unless you get a 12V/6W tire driven dynamo, which costs $325.

Or you could do what sensible people do and use a battery-powered LED
rear light, which, unlike a front light, will run for the best part of a
Randonneur Round The Year season on a pair of AAAs.

No argument there, but someone in this thread was trying to find an LED
bulb for their rear dynamo powered light.

Um, no they weren't. They were looking for a replacement for the front.

I remember seeing LED replacement rear lamps about 15 years ago. Red was
always a lot easier than white.

The whole thing is ridiculous.

No, you are.

You want to not waste any of those 3 watts from the dynamo on a rear
"being seen" light.

Over 10 years ago I fitted my first LED lamp on my dynamo. 3W front, LED
rear. It works with more modern LED front lamps too - IQ Fly and IQ Cyo.
They've been used with both bottle and hub dynamos, and in both cases it
means the dynamo is putting out a bit more than 3W - there's no "waste" as
you describe it. (which reminds me, you still haven't come up with your
numbers yet). Rear lamps don't take much power at all.

Especially because for a rear LED light you want one with multiple LEDs,
at least two of which are side pointing.

Some manufacturers seem to make single LEDs work well. Lenses are wonderful
things.

On Dec 15, 8:41*am, SMS wrote:
No argument there, but someone in this thread was trying to find an LED
bulb for their rear dynamo powered light. The whole thing is ridiculous.
You want to not waste any of those 3 watts from the dynamo on a rear
"being seen" light.

An LED rear light draws what, 0.2 watts at most? (c'mon, you can work
it out from runtimes and the energy density of a battery)

-pm

MasonS wrote:

SMS wrote:

Especially because for a rear LED light you want one
with multiple LEDs, at least two of which are side pointing. Buy a
CatEye TD-LD1100 for $28 and be done with it.
"http://www.lickbike.com/productpage.aspx?PART_NUM_SUB=%273340-00%27"

Run it on 2900 mAh NiMHs and you are sorted.

Actually, a rear blinky is a great application for a low internal
discharge NiMH like the Rayovac Hybrid or Sanyo Eneloop. Even though
they hold 2000-2200mAh, which is less than a conventional NiMH, they
usually need less less frequent charging. They won't be ruined if you
forget about them for a year. A regular NiMH can easily lose more
juice to self-discharge than to running the blinky for a short time
each day.

Chalo