LEDs Not Drawing Amps of Old

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chops728
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LEDs Not Drawing Amps of Old

I have recently changed out a couple of XM-L2s The first being a Maxtoch Mission—I had braided the tail spring and had gotten it to a stable 3.75 amps. I decided I would install a new XM-L2 U3 2A same type copper board—now with a VTC5 lucky if it reaches 2.75amps
I have noticed this on a couple of other occasions with a T6 1D dedome on a Qlite driver went from 5.12amps to 4.6amps and recently with a fet driver I was getting a ridiculous 7.2amps with a U2 1A and after installing a T6 4C it’s only pulling 5.4 but this is closer to the new normal I’ve been getting with fet drivers
I’m wondering if this is what’s going on with the X6 in the group buy

If I put this thread in the wrong place I didn’t know where else to put it

ImA4Wheelr
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You can check to see how high the Vf of the emitter is while the light is on.  Just set your DMM to DC Voltage and place one probe on each of the two electrical contact pads on the copper base.

You may also want to inspect the base of the emitter to see if it looks like it was properly reflowed to the copper base.

Billy X
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interesting

RolandF
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ImA4Wheelr wrote:

You can check to see how high the Vf of the emitter is while the light is on.  Just set your DMM to DC Voltage and place one probe on each of the two electrical contact pads on the copper base.

You may also want to inspect the base of the emitter to see if it looks like it was properly reflowed to the copper base.

i m trying to understand this better, does a higher Vf naturally mean a higher amp drawn ? or is it vice versa?

Rufusbduck
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Higher Vf corresponds to lower current if power out is held constant. On linear drivers the higher Vf is closer to the high point of cell voltage so with a DD driver you get less top end current and with regulated 7135 drivers less time in regulation.

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

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Try a 4.35V cell with a high Vf emitter. Problem is it also has to be a high drain cell as well.

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Scott

RMM
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Yes, it seems like the vF on some of the newer emitters (not just the U3s, but I've seen it with newer batches of T6s also) is higher than it used to be. At first a bunch of us thought that it was the reflow process that had changed, but then several of us reflowed our own using bare emitters and the results were identical, so I'm pretty sure something has changed with the LEDs themselves.  The higher bins do make up for the lower amps somewhat and are more efficient, but those of us who like to hotrod would always like to be able to pull more amps! Cry

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Tom E
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Richard - what's the deal with the U3's though? Same issue of higher Vf or something with the batch of U3's? Haven't seen anything posted on your site or IOS making any note of it. I recall you posted you talked to Hank about it all, but what's the current state of this issue?

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Tom E wrote:

Richard - what's the deal with the U3's though? Same issue of higher Vf or something with the batch of U3's? Haven't seen anything posted on your site or IOS making any note of it. I recall you posted you talked to Hank about it all, but what's the current state of this issue?

Same issue of higher vF.  Like I said, initially I thought it was the reflow, but DBCStm, myself, and several others have reflowed bare U3s and the results have been the same as those received already reflowed.  I also don't think it is just the U3s, as some of the newer LEDs from other bins are the same way.  I have been talking with several other members who told me that LEDs purchased from other sources (not me or IOS) have also not been able to pull as many amps as the older LEDs.  My guess is that there was a process change somewhere along the line, but it is just a guess.  

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Is anyone else apart from me and one other member here using the latest XML-2 U2 and U3 leds having a hard time getting these to run over 5 amps before they die? Around 5.5 amps seemed to be the magic mark. It may be our setups and with the help of others got to the last of my abilities in testing without finding an answer.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

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eebowler
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If they die at around 5.5A, I’d guess bond wires are different,smaller? Would increased resistance in the bond wires account for the increase in Vf?

My gratitude to those who are willing and able to help others (in whatever way you can)! Being human is more than just existing for yourself. Smile

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I think I have posted this elsewhere but cant find it. The measurements were taken at the led for both current and voltage. Keep in mind that my DMM are not calibrated. Power was supplied by a bench power supply.

XML-2 U2                                  XML-2 U3

Volts                   Amps               Volts

3.11                    1                     3.1

3.4                      2                     3.38

3.64                    3                     3.69

3.86                    4                     3.87

4.11                    5                     4.08

Taking into account tolerances these are pretty much identical for both leds. It was suggested to me that the way that I was driving the leds that perhaps I had an issue with voltage ripple killing the leds.

I'm not trying to derail the thread but maybe there is a change in these leds apart from the higher voltage requirements that others may have picked up on as well?

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

Tom E
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Die over 5A? or 5.5A? So do you mean it kills the LED at 5.5A? Are the fine wires melting? Dunno - most of my stock is older. Only have a couple U3's and the ones I've built up in a light are not being pushed (under 4.5A).

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All testing was carried out with heavy wiring to try and eliminate losses. The leds are dying around the 5.5 amp mark. The driver in question about the voltage ripple is a taskled and my power supply was also suggested as being suspect. Hooked directly to the led regulating either the voltage or current from the power supply made no difference to the outcome. I hate to think how many good leds have died in testing and in my lights trying to get above 5 amps. In my C83 l went through a heap of leds until I found three to reliably run at 6 amps each. In the XMTG light I settled on 5 amps per led after lots of testing. 

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

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Hrmpf! That just plain sucks! Unless of course they put out as much light at ~5 amps as the old ones did at ~6,5 A.

~ Ledsmoke ~

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[quote=djozz]

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chops728
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Ledsmoke wrote:

Hrmpf! That just plain sucks! Unless of course they put out as much light at ~5 amps as the old ones did at ~6,5 A.


On the top end it’s hard to say the amount of light output—If you were to have a medium at 5.4 amps and a high at 6.5 amps not sure if there would be much difference
What I have noticed is I buy drivers pre programmed (I’m older and can’t see s….t) the lower modes are always lower than programmed to be—with the patience of RMM I have drivers more to my satisfaction—this is more of an issue to me—lets face it who uses their lights wide open for any period of time
RMM
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Ledsmoke wrote:

Hrmpf! That just plain sucks! Unless of course they put out as much light at ~5 amps as the old ones did at ~6,5 A.

Some of them seem like they are coming pretty close to that.  DBCStm has measured some lights with a U3 at around 5A that are doing about what the old ones did at around 6A.  Dale, care to chime in?  I know that the M6s I build with the U3s all measured 400-500 lumens higher on average than the U2s did.  I have built 100+ of these and measured dozens, so I know the usual range, and the average U3 was as good as the best U2s I've ever measured.  This surprised me a bit, but I can't argue with those numbers.  In some lights, however, the lumens have gone down a little bit but the efficiency has still improved.  

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Rufusbduck
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It sounds like we’re gonna need a bit of data about this.

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Rufusbduck wrote:
It sounds like we're gonna need a bit of data about this.

Looks like we have a volunteer. I'll come around and watch a pro at work. Smile

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

Rufusbduck
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Hmm, needs to be someone with access to cells of all types, hosts with DD drivers, well acquainted with high current testing, and the means and time to do so. It would also help if they were handy with a camera. Hmm…

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

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Rufusbduck wrote:
Hmm, needs to be someone with access to cells of all types, hosts with DD drivers, well acquainted with high current testing, and the means and time to do so. It would also help if they were handy with a camera. Hmm...

It would also come in handy if he/she had 20 mods-a-day capability, hmm...

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Thats at least encouraging RMM. Thanks for the info.

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RMM wrote:

Ledsmoke wrote:

Hrmpf! That just plain sucks! Unless of course they put out as much light at ~5 amps as the old ones did at ~6,5 A.

Some of them seem like they are coming pretty close to that.  DBCStm has measured some lights with a U3 at around 5A that are doing about what the old ones did at around 6A.  Dale, care to chime in?  I know that the M6s I build with the U3s all measured 400-500 lumens higher on average than the U2s did.  I have built 100+ of these and measured dozens, so I know the usual range, and the average U3 was as good as the best U2s I've ever measured.  This surprised me a bit, but I can't argue with those numbers.  In some lights, however, the lumens have gone down a little bit but the efficiency has still improved.

Do you know what the amp #'s are between the U2 and U3 builds? Suspect you are in the 4-5A range?

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Ive got some emitter data that might be interesting. Various testing with driver circuit and batteries or powersupply only. Sometimes with a capacitor on the output. I have been thinking about starting a thread on it for some time, but I have not gotten around to it yet.... I have used a camera and recorded video when testing many of the emitters. Some that I have blown... Might be some interesting data despite that its not a super scientific testing.

Time will tell when I get around to post about it. I have not looked that much at the clips I made yet. But im not super surprised to hear what chops728 reported.

Btw MRsDNF.. Im running 6,6A now. Short story, I found the right emitters.

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RaceR86 wrote:

Ive got some emitter data that might be interesting. Various testing with driver circuit and batteries or powersupply only. Sometimes with a capacitor on the output. I have been thinking about starting a thread on it for some time, but I have not gotten around to it yet.... I have used a camera and recorded video when testing many of the emitters. Some that I have blown... Might be some interesting data despite that its not a super scientific testing.

Time will tell when I get around to post about it. I have not looked that much at the clips I made yet. But im not super surprised to hear what chops728 reported.

Btw MRsDNF.. Im running 6,6A now. Short story, I found the right emitters.

I trust your tests, but also don't want to throw away money on a LED order right now. Is it worth waiting for your posted info? Smile

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I think we need another round of emitter crash testing.

Can we get a volunteer? Wink

Newb

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bdiddle wrote:
I think we need another round of emitter crash testing. Can we get a volunteer? ;)

well, unvoluntarily I did a crash-test of a U3 2A from intl-outdoor in this thread, post 45:

http://budgetlightforum.com/node/34404#comment-668328

But to get the whole picture of the new batch of XM-L2's you need to test many of them. 

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RaceR86 wrote:
Btw MRsDNF. Im running 6,6A now. Short story, I found the right emitters.

Are the XML-2 T6? So do you think there is an issue with voltage ripple with this driver? I'm glad that its sorted for you by the way.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

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I'm willing to do testing if someone can tell me what they want done below 5 amps. Anything above 5.5 amps and I can only blow them up. I also do not have any older generation spare XML-2 U2 or U3 leds. I could pull them from lights though if needed.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

Tom E
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MRsDNF wrote:

I'm willing to do testing if someone can tell me what they want done below 5 amps. Anything above 5.5 amps and I can only blow them up. I also do not have any older generation spare XML-2 U2 or U3 leds. I could pull them from lights though if needed.

Really dunno - dunno what's going on. Seems like conflicting info: Richard says his M6 builds get more output (lumens) with the U3's, but djozz's tests indicate high Vf, mediocre output with the U3's he tested. Your tests in post #11 show virtually no difference in Vf from 1A thru 5A. Others have found high Vf with the new LED's as well, but your tests are the only ones I've seen or heard of where the Vf is basically unchanged between a U2 and U3. Obviously we don't have all the info, and no idea whether sourcing and tint variations is partially to blame.

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Tom E. Hard to say. Depends on what your are going to use the emitters for and what you expect out of them.

Bdiddle and Djozz. Ive got some crash test data that you guys might find interesting along with various data.

MRsDNF. 6,6A to U2 emitters. No, I don't think there are any voltage ripples issues with the H6Flex. 

I hope to post about my emitter testing within few days..

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