White LED lumen testing

[EntropyQ3]

Hi.
A bump and a request.
The request being that you do more fine-grained testing of the powerLEDs at the lowest currents. All non-PWM lights have an interest in not falling off the efficiency peak to the left, so knowing exactly where it is would be quite useful - 5mA, 10mA, 15mA, 20mA? This could help determine where the lowest output level would fall for a current controlled light.

Also wanted to say that this is the thread on CPF that I keep coming back to over and over again to check different aspects of different emitters. A wonderful resource! :wave:

 

[jtr1962]

Hi.
A bump and a request.
The request being that you do more fine-grained testing of the powerLEDs at the lowest currents. All non-PWM lights have an interest in not falling off the efficiency peak to the left, so knowing exactly where it is would be quite useful - 5mA, 10mA, 15mA, 20mA? This could help determine where the lowest output level would fall for a current controlled light.

I'll see if I can do this in the future. Note however that it presents a measurement problem. Generally since power LEDs are wide angle emitters by the time I get down to 20 mA the output is only a few lux at 1 meter. Since my meter on its lowest setting has a resolution of 0.1 lux this introduces some granularity into the measurements. Next few tests I'll try measurements at very low currents and see if I get anything interesting. I vaguely remember when testing a Rebel 100 that the efficiency peaked at ~150 lm/W at 20 mA, and then remained more or less flat until about 3 or 4 mA, at which point it started dropping. Of course, the limited resolution of my meter made these measurements less than than precise.

Also wanted to say that this is the thread on CPF that I keep coming back to over and over again to check different aspects of different emitters. A wonderful resource! :wave:

Thanks for the compliments!

 

[jtr1962]

I just looked at an old PM where someone requested that Rebel 100 test at very low currents which I mentioned in the post above. Here were the results:

1 mA: 117.0 lm/W
5 mA: 147.4 lm/W
10 mA: 152.1 lm/W
15 mA: 152.4 lm/W
20 mA: 150.7 lm/W
25 mA: 149.5 lm/W
30 mA: 148.0 lm/W
40 mA: 145.4 lm/W

Efficiency does remain more or less flat from 30 mA down to 5 mA, at which point in takes a dive. Remember also that regardless of efficiency levels, at some point the current and therefore power input to the LED is so low that light output isn't enough to be useful. For example, at 5 mA you're only getting about 1.9 lumens. Even if efficiency didn't drop you would be getting about 1/3rd of a lumen at 1 mA-not enough to be useful for much of anything. Also, at very low currents the efficiency of most drivers drops dramatically because the supply current to the driver chip becomes an appreciable fraction of the total power. Of course, some drivers are better than others in this regard. Therefore, even if LED efficiency remains flat or increases at low currents, overall system efficiency may still drop, making stepping down current further pointless (except perhaps to extend battery life).

 

[padmab]

Hi,

I came accross this forum when I was searching for LED manufacturers. The information you have been posting on this forum is greatly useful. I am looking for an equivalent led for the one attached below. I am currently buying this from besthongkong. This LED is currently used by us for home lighting applications where LUMENS and Life of the lamp are critical requirements. Can you recommend good alternatives for this ? Thank you in advance for your help

THe LUMEN requirement is 180 + Lumens
2 Watt Power draw or less
12 V input supply voltage (10.5 to 13 V range )
No reverse polarity protection required

Click on the link below for image
http://img38.imageshack.us/i/ledimage.jpg/

 

[DM51]

Somehow, this thread has found its way into the wrong forum - perhaps during the CPF restructuring a while back. It is still a very good reference thread. I'm moving it to the LED forum.

 

[jtr1962]

Somehow, this thread has found its way into the wrong forum - perhaps during the CPF restructuring a while back. It is still a very good reference thread. I'm moving it to the LED forum.

Thanks. :twothumbs The LED forum is really where this thread belongs.

 

[saabluster]

WOW! Its about time. Thanks DM!

 

[DM51]

WOW! Its about time.

Indeed it is. To be honest, I don't know how it was not noticed before that it was misplaced. I remember the thread from quite some while ago, but I can't remember seeing the more recent revivals. As I said above, this one probably wound up in the wrong place by accident, during forum reorganisation or in some such way.

It is not possible for CPF staff to read every single post, or continually monitor every single thread. We rely a lot on members reporting things to us, whether it is a case of misbehavior or a post in the wrong forum. I see there was some comment a few posts above to the effect that this thread kept being bumped down the list too quickly, and there was even the wish correctly expressed that it should be moved from LED Flashlights to LED; but no report or request about this was sent to moderators as far as I can remember, or one of us would have moved it.

Sometimes misplaced posts and even threads just do slip through the net unnoticed. If members see something that needs doing, the solution is to report it directly, giving details of your request or suggestion, either by using the "report post" button, or by PM to a staff member.

 

[saabluster]

Indeed it is. To be honest, I don't know how it was not noticed before that it was misplaced. I remember the thread from quite some while ago, but I can't remember seeing the more recent revivals. As I said above, this one probably wound up in the wrong place by accident, during forum reorganisation or in some such way.

It is not possible for CPF staff to read every single post, or continually monitor every single thread. We rely a lot on members reporting things to us, whether it is a case of misbehavior or a post in the wrong forum. I see there was some comment a few posts above to the effect that this thread kept being bumped down the list too quickly, and there was even the wish correctly expressed that it should be moved from LED Flashlights to LED; but no report or request about this was sent to moderators as far as I can remember, or one of us would have moved it.

Sometimes misplaced posts and even threads just do slip through the net unnoticed. If members see something that needs doing, the solution is to report it directly, giving details of your request or suggestion, either by using the "report post" button, or by PM to a staff member.

I didn't report it because this is what it says when you click on the tab to report.

"Note: This is ONLY to be used to report spam, advertising messages, and problematic (harassment, fighting, or rude) posts."

It does not seem to follow these guidelines. I will make a note to myself to include this exception. I also thought it would be presumptuous on my part to make a formal request that the thread be moved since it was not my thread.

Due to extremely valuable information within this thread it is my recommendation that it be a sticky. It deserves to be there and would certainly be a help to the many CPF users old and new alike. Thanks again.:thumbsup:

 

[saabluster]

Hi,

I came accross this forum when I was searching for LED manufacturers. The information you have been posting on this forum is greatly useful. I am looking for an equivalent led for the one attached below. I am currently buying this from besthongkong. This LED is currently used by us for home lighting applications where LUMENS and Life of the lamp are critical requirements. Can you recommend good alternatives for this ? Thank you in advance for your help

THe LUMEN requirement is 180 + Lumens
2 Watt Power draw or less
12 V input supply voltage (10.5 to 13 V range )
No reverse polarity protection required

Click on the link below for image
http://img38.imageshack.us/i/ledimage.jpg/

First off we need to know what your CRI or color temp requirements are.

 

[HarryN]

Hi JTR- Thank you very much for all of the work and somehow managing to keep it all organized. I have done some very simple testing in the past, and just keeping the data straight is a major task. This thread and the spreadsheets are incredibly useful and interesting.

DM51 - Thank you for all of your efforts with housekeeping on the forum.

Gryloc - One of the lesser promoted features of the K2 is its "anti drooping" epi technology. PL has presented on this at several conferences in the past, but perhaps not very well in their literature.

In a nutshell:
- The die are "less sensitive" to color shifting vs current than in the past, which was already pretty decent
- The die are "less sensitive" to output vs temp than in the past, which used to be kind of average, and now seems to be quite good.
- The die are tested at the stated current (typicall 1000 ma or 1500ma) for color binning. More or less, this makes the color binning more accurate than if they were testing at 350ma.

Perhaps this is part of the reason for the mentioned performance.

JTR - I am probably just somehow missing it, but I could not find the K2 or K2 TFFC results in the thread or on the spreadsheets. (might just be from too much time with flashlights ) Could someone point me to the likely obvious location for the plots - or perhaps JTR - do you need some K2s or LEDEngin LEDs ?

 

[DM51]

Due to extremely valuable information within this thread it is my recommendation that it be a sticky.

Done.

 

[Calina]

JTR - I am probably just somehow missing it, but I could not find the K2 or K2 TFFC results in the thread or on the spreadsheets. (might just be from too much time with flashlights ) Could someone point me to the likely obvious location for the plots - or perhaps JTR - do you need some K2s or LEDEngin LEDs ?

You will not find any information on high power LEDs in this thread, which is about 3, 5 and 10 mm LEDs only.

 

[spencer]

There are multiple tests for power LEDs throughout this thread. You just have to look for them.

Very nice on the sticky idea.

 

[HarryN]

There are multiple tests for power LEDs throughout this thread. You just have to look for them.

Very nice on the sticky idea.

Hi, I have followed JTR's work for some time. Last night and today I went back and read the last 200 posts, as well as downloaded and read both of the zip files. Last but not least, I did a search for K2 and K2 TFFC. At that point, I offered to help JTR with some samples (that I would buy)

I am not saying it is not there, but while I could find rebel and Lux III info, I did not find K2 TFFC info, nor any LEDEngin info. If someone happens to remember what post number it is, please let me know.

Thanks

HarryN

 

[TorchBoy]

Re: White 3mm, 5mm, 10mm LED lumen testing

You will not find any information on high power LEDs in this thread, which is about 3, 5 and 10 mm LEDs only.

Could that be reflected (no pun intended) in the thread title?

 

[Calina]

If they are not referenced in the first post (summary),you might as well consider them lost and the effort is kind of wasted. I don't think a lot of people are going to go through close to 300 posts in the hope that maybe they'll find what they are looking for.

Great thread by the way and thanks to DM51 for making it a sticky.

 

[TexLite]

Indeed it is. To be honest, I don't know how it was not noticed before that it was misplaced.

I always did a search for the thread title, I never looked through the appropriate sub-forum.

Maybe others were doing the same.

Thanks for the forum switch and the sticky DM51.

You will not find any information on high power LEDs in this thread, which is about 3, 5 and 10 mm LEDs only.

Could that be reflected (no pun intended) in the thread title?

There are multiple tests for power LEDs throughout this thread. You just have to look for them.

Very nice on the sticky idea.

If they are not referenced in the first post (summary),you might as well consider them lost and the effort is kind of wasted. I don't think a lot of people are going to go through close to 300 posts in the hope that maybe they'll find what they are looking for.

Great thread by the way and thanks to DM51 for making it a sticky.

As Spencer noted, there are multiple power LED's in this thread, even multi-die emitters.

Maybe links in the first post to the different individual posts of the different emitters would be helpful.

Another alternative would be to click on the individual post number and bookmark the "view single post".

And many thanks to jtr1962 for all the hard work and for the highly informative thread. Congratulations on the sticky.

-Michael

 

[jtr1962]

Hi, I have followed JTR's work for some time. Last night and today I went back and read the last 200 posts, as well as downloaded and read both of the zip files. Last but not least, I did a search for K2 and K2 TFFC. At that point, I offered to help JTR with some samples (that I would buy)

I am not saying it is not there, but while I could find rebel and Lux III info, I did not find K2 TFFC info, nor any LEDEngin info. If someone happens to remember what post number it is, please let me know.

No, I didn't do any tests on the K2, K2 TFFC, or LEDEngin but if you want to send me samples I'll be happy to do so. Thanks also for the compliments and your ongoing interest in this thread. :thumbsup:

If they are not referenced in the first post (summary),you might as well consider them lost and the effort is kind of wasted. I don't think a lot of people are going to go through close to 300 posts in the hope that maybe they'll find what they are looking for.

I'll reedit the first post so that the power LED information is more readily accessible. When I first started this thread, I had no intention to test power LEDs but one thing led to another (no pun intended). Now with smaller LEDs seemingly in a state of stagnation with few new products worth testing, I suspect that the bulk of my future testing will be power LEDs. As such, I agree the information should be more readily accessible without needing to look through some 300 posts. I just need to find the time to do so as my free time has been in pretty short supply the last 2 months.

BTW, thanks to the mods for making this thread a sticky, and to those fellow CPFers who asked for it to be made one. The work is still ongoing even if a little sparse lately. :twothumbs

Almost forgot to ask the mods-is the 10,000 word post limit still in force? Unfortunately, I can't edit the first post or reorganize any info there so long as this is the case since it will cause a lot of the info to be lost.

 

[saabluster]

Almost forgot to ask the mods-is the 10,000 word post limit still in force? Unfortunately, I can't edit the first post or reorganize any info there so long as this is the case since it will cause a lot of the info to be lost.

No. You can edit away.:twothumbs