A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

More About Lights



 
 
Thread Tools Display Modes
  #21  
Old March 6th 17, 08:10 PM posted to rec.bicycles.tech
David Scheidt
external usenet poster
 
Posts: 1,113
Default More About Lights

Frank Krygowski wrote:
:On Monday, March 6, 2017 at 1:37:23 PM UTC-5, AMuzi wrote:
: On 3/6/2017 11:22 AM, Jeff Liebermann wrote:
: On Mon, 6 Mar 2017 17:04:13 +1100, James
: wrote:
:
: On 06/03/17 12:26, Jeff Liebermann wrote:
:
: Well, let's do some arithmetic. If your dynamo is rated at 3 watts,
: and your lighting is rated at 70 lumens/watt, then the most you can
: perhaps deliver is 210 lumens. 6 watts will get perhaps 420 lumens.
: Usually, it's less as the losses accumulate. Rectification losses,
: optical losses, heat degradation, and connector losses all conspire to
: produce lower output.
:
: We know that a 3W dynamo is quite capable of delivering more power than
: 3W, once the bicycle speed increases. 6W from a 3W dynamo is quite
: achievable, and the retardation torque drops off as speed increases too.
:
: Maybe:
: http://www.myra-simon.com/bike/dynotest.html
: See "Electrical Output" graph.
:
: Kinda looks like all of them will sorta deliver 2.5 watts before the
: core saturates (to provide some level of voltage regulation). Further
: down the page is a "Low Speed Power" graph, which shows that most can
: produce 2.0-2.5 watts at 10km/hr. One could assume that the dynamo
: will deliver 4.0 watts, but that would require buying one of the few
: better (hub) dynamos listed, and riding at 25-30km/hr (15-19mph).
:
: If I were designing or sizing a lighting system suitable for my slow
: style of "cruising", I would use the worst case 10km/hr (6mph) and 2.0
: watt figures.
:
:
:
: I don't know about currents but 6V 4W bulbs for standard
: dynamo systems have been around for twenty years and some
: customers like them. I don't know if the dynamo drag is
: noticeably greater.

:6V 4W? I'm aware of 6V 3W bulbs, which are (or were) used mostly with bottle
:dyno systems when driving a headlamp but no taillamp. They were an alternative
:to 2.4 W in front and 0.6W in back.

:I'm not aware of any common use of 6V 4W bulbs.

It's a standard lantern size.

--
But all of a sudden Igor Stravinsky shows up with bag of psilocybin
mushrooms and a chainsaw.... -- Jens
Ads
  #22  
Old March 6th 17, 08:43 PM posted to rec.bicycles.tech
Duane[_3_]
external usenet poster
 
Posts: 1,805
Default More About Lights

On 06/03/2017 2:45 PM, Sir Ridesalot wrote:
On Monday, March 6, 2017 at 2:15:56 PM UTC-5, jbeattie wrote:
On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote:
On 06/03/17 10:22, Barry Beams wrote:


Burn time: What if you had five or ten hours battery time at your
generator's brightness? My Oculus gives at least that much
brightness, and a quickly field replaceable battery so you can put in
a fresh battery. Other rechargeables leave you out of light and out
of luck when the battery drains. Oculus also comes with a spare
battery included.


What if I don't want to play with batteries?


Then you're done with the battery light discussion and may move on to helmets.

-- Jay Beattie.


or carbon frames versus steel frames.

Cheers


I was hoping for bike lanes...
  #23  
Old March 6th 17, 09:03 PM posted to rec.bicycles.tech
Doug Landau
external usenet poster
 
Posts: 818
Default More About Lights


What if I don't want to play with batteries?


Then you're done with the battery light discussion and may move on to helmets.


or carbon frames versus steel frames.



Stainless!!!
http://gearpatrol.com/2017/01/26/bes...l-bike-makers/

  #24  
Old March 6th 17, 09:33 PM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 3,411
Default More About Lights

On 2017-03-06 10:47, wrote:
On Sunday, March 5, 2017 at 5:26:18 PM UTC-8, Jeff Liebermann wrote:
On Sun, 5 Mar 2017 16:03:30 -0800 (PST),

wrote:

Thanks Jeff. These however all appear to be battery powered
lights. We were sort of looking for lights that operated on the
hub dynamo of 6V 3W or the Globe dynamo of 12V 6W or four times
the power.


Sorry, I thought you were still open to looking at battery powered
lights. Here's what I fished out of my bookmark dumpster. No
reviews and few tests, but some interesting dynamo graphs and
numbers: http://www.myra-simon.com/bike/dynotest.html
http://pilom.com/BicycleElectronics/DynamoCircuits.htm
http://www.eeweb.com/blog/extreme_circuits/power-mosfet-bridge-rectifier



This one is well worth reading (or skimming) and has quite a few test
results:
http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_en.html

This is why the hub generator has so little drag.


Well, let's do some arithmetic. If your dynamo is rated at 3
watts, and your lighting is rated at 70 lumens/watt, then the most
you can perhaps deliver is 210 lumens. 6 watts will get perhaps
420 lumens. Usually, it's less as the losses accumulate.
Rectification losses, optical losses, heat degradation, and
connector losses all conspire to produce lower output.

You might find it useful to know how bright you want your light.
For that, you'll need a Lux meter. I have a Lutron LX-102 which
works nicely, and two junk meters I bought on eBay for sanity
checks: http://www.ebay.com/sch/i.html?_nkw=lux+meter Get one
that has a wide range. Lowest on mine is 1000 lux, and highest
range is 50,000 lux.

Find a dark night and an accomplice to operate the meter and send
them down the road to the farthest distance that you might want to
illuminate with your headlight. Use a headlight or flashlight to
light up that area. Have your accompli's take a reading. It will
probably be zero. Now, cut the distance in half and take a
measurement. It will be 2x as bright (lux) at half the distance or
4x as bright at 1/4th the distance. Adjust the brightness for what
it would have been if the light meter was sufficiently sensitive.

Converting the brightness (lux) to luminous flux (lumens) requires
that you know the distance to the accomplice, and the illumination
angle. (1 lux = 1 lumen/square-meter)

The form below makes a mess of bad assumptions but is good enough
for a rough approximation:
https://www.ledrise.com/shop_content.php?coID=19 Once you know
how many lumens you think you need, and have adjusted for overly
ambitious expectations, you can determine which lighting technology
is suitable.

Lets say you want to see 8 meters ahead and 20 degrees to each
side (or 40 degree conical beamwidth) at 20 lux, which is rather
dim. Plugging into the web page above, I get 485 lumens needed.
You won't be able to do that with a 3w dynamo, but might squeeze by
with a 6w and an oval shaped beam.


-- Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com Santa Cruz CA 95060
http://802.11junk.com Skype: JeffLiebermann AE6KS
831-336-2558


As a very occasional night rider I am interested in battery powered
lights but I think that I was attempting to give a thought to a
commuter that would use his light a great deal.


I use my lights a great deal because they are on during the day as well
except on segregated bike paths.

Recharging is 2nd nature to me. Bike gets parked back in the garage,
li'l round connector gets plugged in, done. Sometimes I deliberately do
not charge past 8V until shortly before a ride. That improves battery
lifetime.

The real McCoy would be a worryfree system like in a car where it
recharges while riding. If I ever switch the road bike front wheel to
one with a hub dynamo I will do that. Right now it only has a bottle
dynamo, too much drag and it eats the left side wall of "modern" tires.
Power output of those is well above 3W at higher speeds if you provide
the proper electronics. I could go into that but it's nerdy tech stuff.
Essentially you need what is called a SEPIC or at least a buck converter
plus some sort of maximum power point tracking (MPPT) control for that
converter. Sounds more complicated than it really is but do not expect
the bicycle industry to deliver anything even remotely close anytime soon.

Realistically you could eke out 4-6W depending on you speed. That's not
enough to feed a MagicShine clone which wants 8W on high plus a watt or
so for the rear lights. And maybe another 1-2W for the MP3 player. Plus
the smart phone. And the electric razor :-)

In my case this would work nicely because I need the full 10W total only
on county roads and in city areas where car drivers tend to misbehave.
Else it drops to a net load of 4-5W or even much lower. So the dynamo
would recharge the watt-hours you used up on the county road. Once the
battery gets full it throttles back. Just like in car.


I notice that a large number of the people in our group have flashing
red rear lights and it isn't long before these batteries run down
enough that the taillight even blinking is almost entirely
unnoticeable. So I don't have much respect for battery power for a
great deal of use.


Yep, that's a major nuisance. However ... one can power these lights off
a regular 8.4V Li-Ion battery or even a dynamo (after rectification) by
providing a 3V regulator. Small enough to fit where the two AAA cells
used to be.

If battery rear lights at least had a low-battery warning. Technically
that would be a piece of cake. But no ... nothing :-(

--
Regards, Joerg

http://www.analogconsultants.com/
  #25  
Old March 6th 17, 09:39 PM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 3,411
Default More About Lights

On 2017-03-06 13:03, Doug Landau wrote:

What if I don't want to play with batteries?

Then you're done with the battery light discussion and may move on to helmets.


or carbon frames versus steel frames.



Stainless!!!
http://gearpatrol.com/2017/01/26/bes...l-bike-makers/


Nah, wood!

https://connorcycles.com/

--
Regards, Joerg

http://www.analogconsultants.com/
  #26  
Old March 7th 17, 12:50 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,270
Default More About Lights

On Mon, 6 Mar 2017 20:10:38 +0000 (UTC), David Scheidt
wrote:

Frank Krygowski wrote:
:On Monday, March 6, 2017 at 1:37:23 PM UTC-5, AMuzi wrote:
: I don't know about currents but 6V 4W bulbs for standard
: dynamo systems have been around for twenty years and some
: customers like them. I don't know if the dynamo drag is
: noticeably greater.


:6V 4W? I'm aware of 6V 3W bulbs, which are (or were) used mostly with bottle
:dyno systems when driving a headlamp but no taillamp. They were an alternative
:to 2.4 W in front and 0.6W in back.


:I'm not aware of any common use of 6V 4W bulbs.


It's a standard lantern size.


http://www.rayovacindustrial.com/Products/Lights/Bulbs/K13-2TB-Krypton-Bulb-for-4D-Flashlights.aspx
Ray-0-Vac K13-2TB. Made for 4D cell lanterns. 6v 3.6 watts.
I couldn't find a 4 watt version. Most of what I found were 2.4 and
3.0 watt bulbs for bicycles.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #27  
Old March 7th 17, 02:27 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,270
Default More About Lights

On Mon, 6 Mar 2017 10:47:34 -0800 (PST), wrote:

As a very occasional night rider I am interested in battery
powered lights but I think that I was attempting to give
a thought to a commuter that would use his light a great deal.


Do "occasional night riders" buy $150 headlights?

I notice that a large number of the people in our group
have flashing red rear lights and it isn't long before
these batteries run down enough that the taillight even
blinking is almost entirely unnoticeable. So I don't have
much respect for battery power for a great deal of use.


Well, that's one of the advantages of a dynamo. You never have to
worry about a dead or discharged battery or remember to carry a spare
dead or discharged battery. (Yes, I've done that).

I think you'll find a fair number of riders in your group using low
cost rear flashers like this:
http://www.ebay.com/itm/142066277090
$0.97 gets you a two AAA batteries packaged inside a flasher (postage
included). That's about the same price as the batteries, assuming
that they're alkaline and not carbon-zinc. One of my friends says
that he picks them out of the trash at the end of club rides because
people just toss them instead of trying to figure out how to pry open
the case and change the battery. It wouldn't do them much good even
if it was easy to open, because the COB (chip on board) electronics,
buried under a blob of epoxy, will self destruct if you touch, bend,
or push on it. As for not noticing a failure, most club riders will
inform your if they see a problem.

I don't think it's fair to compare a $150 headlight, with a $0.97 tail
light. Others have mentioned various schemes to get more out of a
tail light. There are tail lights available or under design that have
motion sensors, LiIon battery, low battery indicator, solar charging,
USB charging, dynamo charging, wireless charging, side lighting,
programmable flashing, high brightness daylight mode, motion alarm,
automobile tailgating detection (via a bright headlight detector),
Bluegoof telemetry, and whatever else I forgot. Of course, they don't
cost $0.97.



--
Jeff Liebermann

150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #28  
Old March 7th 17, 02:37 AM posted to rec.bicycles.tech
SMS
external usenet poster
 
Posts: 7,725
Default More About Lights

On 3/5/2017 5:26 PM, Jeff Liebermann wrote:
On Sun, 5 Mar 2017 16:03:30 -0800 (PST), wrote:

Thanks Jeff. These however all appear to be battery powered
lights. We were sort of looking for lights that operated on
the hub dynamo of 6V 3W or the Globe dynamo of 12V 6W or
four times the power.


Sorry, I thought you were still open to looking at battery powered
lights. Here's what I fished out of my bookmark dumpster. No reviews
and few tests, but some interesting dynamo graphs and numbers:
http://www.myra-simon.com/bike/dynotest.html
http://pilom.com/BicycleElectronics/DynamoCircuits.htm
http://www.eeweb.com/blog/extreme_circuits/power-mosfet-bridge-rectifier

This one is well worth reading (or skimming) and has quite a few test
results:
http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_en.html

This is why the hub generator has so little drag.


Well, let's do some arithmetic. If your dynamo is rated at 3 watts,
and your lighting is rated at 70 lumens/watt, then the most you can
perhaps deliver is 210 lumens. 6 watts will get perhaps 420 lumens.
Usually, it's less as the losses accumulate. Rectification losses,
optical losses, heat degradation, and connector losses all conspire to
produce lower output.


WE passed 70 lumens per watt a long time
ago.http://www.cree.com/LED-Components-and-Modules/Products/XLamp/Arrays-Directional/XLamp-MKR.
And bicycle light manufacturers are early adopters of the latest LEDs.

A dynamo can produce more than 3 watts at high speeds. In the olden days
of incandescent dynamo lights there was protection circuitry to limit
the power to the bulb by cutting off the voltage over 6V. But these high
power LEDs can handle 15W so there's no need to limit the power.

This light http://supernova-lights.com/en/supernova-e3-triple-2 claims
640 lumens at 4.5W. 4.5W is definitely possible from a nominal 3W
dynamo. It claims 800 lumens peak.

Note that his light, while sold in Germany, is not "road legal."
because, according to reviews, it doesn't suffer the problems of StVZO
lights, "It has a very broad light output that is closer to a floodlight
than a focused beam, and so doesn’t give the ‘tunnel’ effect of some of
the powerful battery-powered lights. This means it’s great for
illuminating branches and hazards above you and off to the side." As we
all know, the problem with StVZO legal lights are related to the
extremely focused spot beam. The best option, to avoid annoying others,
is to not use the highest settings when riding on narrow roads or paths.
You don't want endanger yourself by using sub-par StVZO lights unless
it's mandated by law.
  #29  
Old March 7th 17, 03:41 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,270
Default More About Lights

On Mon, 6 Mar 2017 18:37:14 -0800, sms
wrote:

WE passed 70 lumens per watt a long time
ago.http://www.cree.com/LED-Components-and-Modules/Products/XLamp/Arrays-Directional/XLamp-MKR.
And bicycle light manufacturers are early adopters of the latest LEDs.


I got burned badly when I specified an LED that was rated at 100
lumens/watt, and got something that was about 70 lumens/watt. If you
look at the Xlamp MK-R data sheet at:
http://www.cree.com/~/media/Files/Cree/LED-Components-and-Modules/XLamp/Data-and-Binning/XLampMKR.pdf
the footknots always says:
"Flux values @25*°C are calculated and for reference only."
I'm not sure exactly what that means, but from my limited experience,
it means that if you pulse the power to the LED with a very short duty
cycle, you might get something near the rated efficacy. If you run it
on DC, it won't even come close. Calculated also means that they
didn't bother to verify their own calculations with an integrating
sphere measurement.

Assuming 200 lumens/watt and 1000 lumens output, that would require 5
watts of input power. Looking at the same data sheet (Pg 15) the 6v
chart shows that 5w is 5.8v @ 0.85A. So far, so good. However, if we
look at the Relative Flux Vs. Current (tJ = 85*°C) graph on Pg 16, the
output is derated to 65% of 1000 lumens. Producing only 650 lumens.
Using those numbers, the efficacy is now:
650 lumens / 5 watts = 130 lumens/watt
Note that the 85C is the junction temp, not the case or heat sink
temp.

Then, there is matching LED chips. See Pg 20
"Performance Groups - Luminous Flux (Tj = 85*°C)"
where one can pick the chip output anywhere from about 515 to 1290
lumens. What is not obvious is that the efficiency also drops at the
lower output levels, resulting in even lower lumens/watt.

Then there's the loss in output due to reflectors and lenses and the
increase of input current from current regulator losses. I would
guess(tm) 15% loss of lumens to the optics, and 10% for the regulator
efficiency. So, we start with
650 lumens / 5 watts = 130 lumens/watt
and end up with:
650 * 0.85 / 5 * 1.1 = 553 / 5.5 = 100 lumens/watt

Can you see where this is going? In the end, the lumens/watt value
for the end product is the light output including all the optics,
divided by the power input as measured from the battery, and derated
by the chip junction temperature.

A dynamo can produce more than 3 watts at high speeds.


I don't ride at high speeds. I'm slowly converting one of my machines
to a "comfort" bicycle.

In the olden days
of incandescent dynamo lights there was protection circuitry to limit
the power to the bulb by cutting off the voltage over 6V. But these high
power LEDs can handle 15W so there's no need to limit the power.


Yep. So why do many dynamos still use the increased inductive
reactance at higher speeds (and higher frequencies) to provide this
voltage limiting? It would be easy enough to reduce the winding
inductance and allow the voltage to increase linearly instead of
flat-topping. The manufacturer might be afraid of blowing something
up with too much voltage at high speeds.

This light http://supernova-lights.com/en/supernova-e3-triple-2 claims
640 lumens at 4.5W. 4.5W is definitely possible from a nominal 3W
dynamo. It claims 800 lumens peak.


640 lumens / 4.5 watts = 142 lumens/watt measured "warm".
If they start out with a 200 lumens/wall LED, that might be possible.
Ok, I stand corrected, but I'm also suspicious.

I couldn't find any test reports or method used on the Supernova site.
I did find this test of the M99 model:
http://supernova-lights.com/en/blog/supernova-blog-1/post/first-test-performance-supernova-m99-pro-br-36
1100 lumens / 16 watts = 68.7 lumens/watt. Hmmm...

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #30  
Old March 7th 17, 04:00 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 4,426
Default More About Lights

On 3/6/2017 4:33 PM, Joerg wrote:

The real McCoy would be a worryfree system like in a car where it
recharges while riding. If I ever switch the road bike front wheel to
one with a hub dynamo I will do that. Right now it only has a bottle
dynamo, too much drag and it eats the left side wall of "modern" tires.


I've done well with a bottle dynamo whose drive wheel has an added
circumferential groove to hold a thick O-ring. That O-ring runs on the
rim's braking surface, not on the tire. Zero tire wear, and it runs
very smoothly. I've experienced no slipping - but it's not been tested
in the rain.


--
- Frank Krygowski
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Dynamo Lights viz Battery Lights in snow qand slush? Sir Ridesalot Techniques 6 March 4th 15 10:36 PM
No lights, dark clothing, no reflectives, no street lights. Mrcheerful UK 153 November 4th 14 09:19 AM
Maybe it's safer to run red lights than to wait for green lights. SMS General 16 September 24th 08 09:51 PM
Light Theft (solutions — small pocket lights, or heavy duty well secured lights?) David Johnson UK 24 August 29th 07 02:32 PM
Break lights turn lights and handle bar lights Truepurple Techniques 30 November 17th 03 04:02 AM


All times are GMT +1. The time now is 11:36 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright ©2004-2017 CycleBanter.com.
The comments are property of their posters.