Re: (ET) ET Headlights

["David Roden" <etpost drmm net>]

On 19 Feb 2016 at 19:26, Steve Welch wrote:

> direct replacement LEDs: 
> http://www.m4products.com/1142-17-5630-nw-natural-white-elite-series-wi
> th-brighter-samsung-5630-leds-1142-1076-ba15d-base/ 
> 

Watch out for those "calculated lumens."  That usually means the spec 
writers have simply summed the rated maximum output of the emitter chips 
used.  The catch is that the chips can't all run at maximum output 
continuously because they'd overheat, so they never deliver their full 
outputs in these retrofit bulbs.

I don't own a meter that measures lumens.  That's lab stuff and expensive. 
 
To approximate the lumen output of various CF and LED retrofits, I use 2 
cardboard boxes (they really should be spheres) of the same size, lined 
with 
white paper.  I turn off the room lights and put the test light in one 
box.  
Then I try various incandescents in the other box until I find the closest 
match in apparent light output. (The human eye is actually pretty good at 
matching apparent illumination.) Since the incandesent bulbs have rated 
lumen outputs, that gives me a rough estimate of the retrofit's lumen 
output.

I've yet to try a 12v like this, but I've tried a few 120v multi-chip 
("ear 
of corn" type) LED retrofits, all of them made in China.  I find that they 
typically produce about one-third to one-half the claimed output.  

I looked on the website above.  M4 products claim 640 "calculated lumens" 
for this little guy.

They say it uses Samsung 5630 chips, but I can't quite tell from the 
photos 
how many (usually the specs say, but these don't).  It looks like it has 5 
on the end and 5 or 6 pair around the sides, so maybe 15 or 17.  

The Samsung 5630 chip comes in various output ranges from S1 to S3.  
Depending on range, it's rated for an absolute max of 28 to 32 lumens at 
4000K CT.  Thus I don't see any way that this retrofit manufacturer (more 
likely importer) could even calculate 640 lumens.  Seventeen of these 
chips 
would have a "calculated" output of 476 to 544 lumens.  And as I say, you 
can't expect to get that output in the real world anyway.

http://www.samsung.com/global/business/business-
images/led/file/product/lighting/201312/Data_Sheet_LM561B_Rev.006.pdf

Another odd thing.  The retrofit bulb specs claim a CT of 4500K.  Samsung 
doesn't show a 4500K chip in the spec sheet.  Tthey jump from 4000K to 
5000K.  That could be an error in the bulb specs on the website, or the 
chips they're using might be knockoffs.  

I'd say put a retrofit in one side, incandescent in the other, and try the 
lights.  If the pattern is similar enough, you can usually tell which is 
lighting up the garage wall better.  And even if the retrofit has less 
output than the GE factory incandescent, you may find that you see better 
at 
night with it because of its higher CT.

Please report back on how it goes.  

In the end, if you're satisfied with the performance and think you got 
your 
money's worth, then that's what counts.  


David Roden - Akron, Ohio, USA

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