When Tesla starts making bikes, you guys will have to eat your words. -- AJ

On Monday, February 26, 2018 at 4:58:12 AM UTC, Jeff Liebermann wrote:
On Sun, 25 Feb 2018 18:58:00 -0500, Frank Krygowski
wrote:

On 2/25/2018 6:17 PM, Jeff Liebermann wrote:
On Sun, 25 Feb 2018 14:43:04 -0500, Frank Krygowski
wrote:

(* I guess I should use kilo-lumen instead of mega-lumen. The latter
probably won't be available for a year or two.)

1.29 MegaLumens available real soon now:
https://www.youtube.com/watch?v=LStmsIyGldA
Whether it actually delivers 1.29 MegaLumens is questionable.

It's very bright, but they're claiming 1.29 MegaCd, which is not the
same as 1.29 Mega lumens. (And note that the solid angle of that light's
beam is tiny.) At about 9:00 he claims 1887 lm. That's solidly in the
kilo category.

Oops, false alarm and wishful thinking on my part. Sorry.

But it's true that nothing exceeds like excess.

Bigger numbers always sell better. The problem with megalumen LED's
is that using the best of todays technology, LED's will deliver about
150 lumens/watt. In order to produce 1 Megalumen, the LED's will
requi
1,000,000 lumens / 150 lumens/watt = 6,666 watts
The better 18650 LiIon cells can deliver perhaps 2A without adversely
affecting the battery life (in charge cycles). To deliver 6,666 watts
will requi
6,666 watts / (2A * 3.6V) watts/cell = 926 cells
I suspect that might be a little too large and heavy to be
successfully installed on a bicycle.

The lamp will also be a problem. It will probably use the current 100
watt LED technology, which produces about 6,000 lumens per LED. Notice
the drop to 60 lumens/watt for these monsters. To produce 1 Megalumen
with 100 watt LED's will requi
1,000,000 lumens / 6,000 lumens/watt/LED = 167 LED's
In terms of size, they are about 40 x 40 mm = 0.0016 sq-meters
167 of these would occupy:
167 * 0.0016 = 0.267 sq-meters
If this were a square, it would be about 0.5 meters on a side, which
is probably too large for a bicycle.

Therefore, you can sleep easily and worry free tonite and not have
nightmares of Megalumen lights appearing at your next ride.

And BTW, the pitchman is just a _little_ over the top! I think he's - um
- in love.

Everyone has their own style. At least he's not dull and boring like
many YouTube presentations[1]. Hmmm... I wonder if I should do a
YouTube video demonstrating my method of measuring lumens?


[1] This is a common problem among speakers accustomed to giving live
presentations to an auditorium audience and then switching to YouTube
videos. In order to convey enthusiasm, the speaker uses various body
gestures and facial expressions that are difficult to see in an
auditorium. So, the speaker intentionally exaggerates these gestures
and expressions so they can be seen. However, when doing a YouTube
video, or while being recorded from a TV camera, the camera is a few
feet away and every little gesture and expression can easily be seen
by the audience. If the speaker acts the same in front of the camera
as they might do in front of an auditorium audience, the gestures and
expressions look grotesque and very un-natural. I suspect this might
be the excess enthusiasm that we're seeing in the video.

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