On Tue, 02 Oct 2018 04:18:35 +0200, Emanuel Berg
wrote:

Jeff Liebermann wrote:

Ok, let's do the math.

I put a flashlight to the handlebars the other
day with re-openable cable ties. It seems to
work OK, a pretty solid fix. I cut the cable
ties with a combination plier so it looks neat
as well.

The flashlight is 3*AAA batteries with
9 diodes. How many lumens is that, do
you think?

Not enough info. Measure the current drain from the battery and I'll
give you a good guess(tm). I just happen to have a similar flashlight
handy, so I measured mine at about 160 ma. At 4.5V, that's 720 mw.
Generic T1(3mm) white LED's typically have an efficacy of about 20
lumens/watt. So the output would be:
0.720 watts * 20 lumens/watt = 14 lumens
I did a quick double check with my lux meter and measured 16 lumens.

Here's how it's done:
https://groups.google.com/d/msg/rec.bicycles.tech/UJdJQFTDgl8/NgOZUloVCwAJ
I was going to turn it into a web page, but after the rather
discouraging response I got from this newsgroup and two other forums,
I decided I had better things to do.

AAA Alkaline cells run about 900 ma-hr capacity, so at 720 ma, you get
maybe 1.3 hrs of operation.

I think I should get a proper bicycle light
soon tho.

Yep, good idea:
http://www.learnbydestroying.com/jeffl/pics/bicycles/slides/bicycle-flashlight.html

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