Emitter data and talk. A look at Vf, amps and some crash testing (Updated with more data 10th of December)

Did a quick test on two emitters from the Supbeam X60. I stopped testing at 3 and 5A. Not suitable for really high amps. I have not added them to the spreadsheet. One were bad the other one were really horrible.

If anyone at some point stumbles on a batch of high binned XM-L2`s (preferably U3 if CW, or U2 if NW) with consistent low Vf, let me/us know..

I haven't tried pushing the single XP-Ls as hard simply because I don't have any lights that I've wanted to put them in yet. 99% of the XP-Ls I use go into small triples with a single cell where vF is not an issue.

This is anecdotal but Hank (from IOS) told me that in the emitters he's tested the XP-Ls could go up to 1A higher than the newer XM-L2s. What I don't know is if the process or construction has or change on the XP-Ls to match the newer XM-L2s but we just haven't seen those emitters yet.

A couple of possibly stupid thoughts (on my part) but maybe relevant......

For the LED manufacturers, but not to be ignored, the usage of LED's in flashlights is an off-shoot and not their mainstay.

I have 35+ years in the automotive repair side of things and 16 years in the sign business. Concentrating on automotive - the common DC voltages for automotive are 5, 12, and 24. For the last 20 years the electrical systems have been over-taxed tremendously. Just not enough available amps at 12VDC and the 48VDC system was deemed long ago to be too expensive and dangerous at the time. Amperage draw is a killer.

The usual lighting systems of the prior 75 years was just too taxing. Instead, manufacturers started looking for ways to drop the current draw to allow for more wanted toys and computer controlled systems. The first line of thought was fiber optics but again that was cost prohibitive to use on everything but higher line vehicles. Instead, the most prominent of the last 10 years was the implementation of LED lights. .

Now if I was an automotive engineer I could see myself telling CREE and companies that I would love to use more LED's but because of the electrical system's limitations that I will just keep pushing forward with fiber optics. Based on what I am learning here at BLF that is actually happening. The LED manufacturers are creating more efficient LED's with the equivalent wattage but lower draw.

So what is "our" next move?

Higher voltage batteries and forsake the high drain batteries? (I am not referring to 2 or 2+ cell lights).

Is anybody aware whether or not the battery manufacturers have anything in the pipe?

Would the focus of higher voltage batteries also change/increase the focus on mAh capacity?

Again, possibly stupid but maybe relevant - dunno :) More qualified people here than I to hopefully answer :)

I am still curious to hear thoughts about the increased Vf of the new emitter and possible solutions.

I have been thinking about this and speaking with many others and all seem to say that greater voltage would be required which leads me to think about boost drivers for single cell lights.

Here are a couple more questions that I have:

What component regulates voltage on a driver?

Does anybody here have a way to test an emitter only with a higher voltage but lower amps? (I would ask RMM but he is busy as hell right now :) )

On the topic of resistance mods: I have a luxon K2 light that I did spring bypasses throughout the whole thing. On 3AAA duraloops, I could approach an amp vs the stock 500 ma it gave me with 3 duraloops.

Can we get one of these high Vf LEDs into an integration sphere and see what is going on?

anyone tested the xp-g2 s3 ?

I bought watts up watt meter and I want to find the amps and vf of my emitters. Is this set up ok?

No, you need something to limit/set the current (driver) and a heatsink for your ledboard. Without driver the led runs direct drive on the battery which may or may not work, that current (-6A) is already dangerously close to fatal to the newer Cree leds.

The noctigon is attached to the heatsink. I just tested it in my xp-g2 s3 3c on noctigon from intl-outdoor. I got 4.65A, 4.08v. I just connected the battery for about 2 seconds then disconnected it to get the readings in my watt meter. Then I discharged the battery to around 3.8v using load resistor, then connected again the battery to watt meter to get the reading. I do this at a decrement of 0.05v.
Here is what i got, I don’t know if that’s the correct way of getting the vf.
3.56A 3.81v
3.21A 3.75v
3.01A 3.7v
2.73A 3.65v
2.55A 3.6v
2.30A 3.55v
2.05A 3.5v
1.8A 3.45v
1.7A 3.4v
1.5A 3.35v
1.4A 3.3v

that looks like a workable way to do the readings without need of a powersupply :-) Do I understand correctly that the voltages were under load? (namely the readings from the watt-meter).

It is indeed the correct way to measure the Vf. The only measurement error is that there is a slight voltage loss in the wires to the ledboard, but if these wires are not overly thin that is not significant.

why i get so late the important threads ???
Race big thank you for this voluminous and time consuming job. i think this is really big help to us that like to play and experiment with flashlights.
that said, i feel very sad about the directions cree is going (assuming the last batches are not defective ones or just isolated batches )
as i see it they are going in the opposite directions of what i would like to see.
first no effort in new dies with increased luminance, but instead they go easy path adding 4 existing dies and present it like a new one :frowning:
not only this they take an existing die again cut here and there and again present like a new thing….
and now this, probably they are in saving cost revisions and the old gold cree we like so much can no longer be overdrive so much :_(
really hope this is not at all true…

Yes the voltages were under load. I am also thinking that there is a slight voltage loss because of the wire. The wire from watt meter is 14 awg.
I did another test this time xp-g2 s2 1d from intl oudoor. Very disappointed by this, i can only get maximum of 2.5A 4.1v. Do you think it’s faulty?
I have another xp-g2 s2 1d and i get 4.5A 4.07v.

Any plans to crash test some XM-L U3-1As? Specifically from the $3.45 deal @ LEDDNA. I have an S6 build that I decided to use an XM-L2 U3-1A instead of the XM-L U3-1A, but I cannot get it going beyond 3.4A presumably because of the higher vF. Was thinking if I'd be able to drive it harder with the older gen emitter...

I tried searching, but I couldn't find anything to save my life :(

One thing I like about using nimh AA is that you don’t have to worry about high Vf beyond figureing out how to fit more cells into the light.
And to think I was trying to figure out a way to run a 3S XML light off of 8S eneloops because the sum of the vFs of the LEDs at 3A was around 9.1V

Does anyone has any update on your overdriven XM-L2 U2/U3 emitter? Are these emitters still incapable of handling >5.5A?

I havent heard otherwise. if you want to drive this size led harder you have to use the XPL.

I see, so the XP-L is fine to be driven >6.5A so far?

I have killed XP-L's at unexpected low currents (<7A) as well, it is not just XM-L2 that shows the problem.

If the XP-L can survive >6A but <7A then it is still good to me. :slight_smile:

Looks sort of like the left hand bond wire lifted from the die in pic 4 of Post 5 . Poor die connections could be one source, another could be the use of weaker bond wires or a manufacturing process that has changed. Cree might not care about over current failures but mechanical failures like bond wires coming off the die could happen in normal use and should raise QC concerns. If this is the weakest link then maybe they will develope more LEDs that do no use bond wires.