#10
|
|||
|
|||
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 |
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 |