#21
|
|||
|
|||
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
|
|||
|
|||
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
|
|||
|
|||
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/ |
#25
|
|||
|
|||
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
|
|||
|
|||
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
|
|||
|
|||
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
|
|||
|
|||
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
|
|||
|
|||
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
|
|||
|
|||
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 | |
|
|
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 |