Results: Testing XM-L, MC-E, SST-50, and XP-G emitters **Updated**

I'd just like to point out that tailcap current is normally not what actually even goes into the driver unless it's a twisty light. Most tailcaps offer significant resistance, this has less of an effect on regulated drivers but with the Manafont 3 mode it has quite a big impact. My L2p tailcap consistently lowers the actual current by about 0.5A from what I read over the tail cap but not through the actual tail switch. The basic L2 switch lowers current a little bit more again.

So, if you read 3.6A on the tail while using the DD manafont drop-in, once you put the tailcap back on the led will probably only see 3.1A of it.

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Great information in this thread, I'v wondered when XM-L would simply start to overrev.

3.25A looks to be a realistic ceiling.

I registered because of this thread,..thanks

Welcome to BLF, Orbital!

Regarding resistors in series vs parallel

In a normal situation - lets call it a DD circuit.

Series - will add a resistance to the whole circuit, reducing overall current draw. Since current passing through each component in the series circuit is the same, the LED will be receiving reduced current draw.

Power in watts is the current multiplied by the voltage drop across each component. The emitter will drop between 3-4V depending on what it is, and what current flows, the resistor can drop any voltage depending on its value.

Parallel - The resistor is effectively independent of the LED because current can flow both "circuits"; the LED or the resistor. Remembering that current draw is determined by the resistance of each circuit, the LED will draw its own current, the resistor will draw its own current and will not affect each other.

With an ideal power supply, the resistor will simply draw current, and make heat. The LED will also do its own thing, as if there was no resistor. So essentially all thats happening is that more power is being drawn

This changes however in a Current Controlled circuit. If your circuit is able to run in regulation, and has enough voltage excess, the 'better' way to reduce power to the emitter is to put a resistor in parallel with the emitter, because the total current flow is limited to X amps. A resistor in parallel will in this case be dividing the current.

A resistor in series will be increasing the total resistance (voltage drop) of the circuit if driven by a constant current driver, and will increase the power draw at the battery end to deliver the same current output. So in that case we will be pushing the same current through the emitter and the resistor. We will effectively just be creating more heat in the resistor, with no reduction in current to the emitter.

The only reason why this is confusing is because we are using current controlled circuits, it reverses the ideas sometimes. This is an example where it can be sometimes counterintuitive. Like for example, when I want to measure the current output of these drivers, I just select the amps setting and short out the driver (only TRUE CC drivers) with the DMM. This short has a very low resistance and normally lets lots of current through, but in a TRUE CC driver it will effectively be drawing almost no power to maintain those 3A. If the driver is not a true CC driver, it will let more amps through and possibly die..

On the other hand open circuits are destructive to TRUE CC boost drivers, with the boost voltage potentially rising very high and killing itself.

And thanks match for the datapoints! Invaluable data!

And thanks for the linear scale graph brted - looks beautiful how all those datapoints line up soo well, thanks to match

First post now updated to reflect testing of the cree MC-E emitter. Test procedure was performed exactly like the xm-l.

Post is now sticky'd for easier reference.

p.s. - Welcome Orbital! Glad to be of assistance.

Folks,

Testing complete and up in the first post for the SST-50. Thanks again goes to BobK for providing the emitters for testing. From the results it's clear that the SST-50 is still alive and kicking in applications above 4 amps.

Great work, Match! I really appreciate the effort as do, I'm sure, we all!

Great work. Very useful also for mod with hard driven emitter. Thanks Match!

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thanks Match

Will there be a test for SST90?! Thank!

Match, thank you for your valuable information with these tests. I have had a 3-4 XML build swirling around in my head and this thread is rich on information. It also answered my curiosities on the SST50's. I know the thread is a bit dated now, but hey, I'm the "new guy". Im guessing that similar info is at cpf but it seems I can hardly stand looking over there for more than 5 minutes at a time.

Have you done a "pop" test for giggles on a XML?

Also something else I would like to see charted- temperature on a smaller given heatsink say after 5 minutes being ran at 2.4A and the same test at 3A.

When I say poof test I meant cranking it up (A) on the bench until critical failure.

Match, really thanks for all this effort to provide some good results with a scientific method.

But i am pretty sure that you have done a major mistake in your test methodology, the pcb. You are suffering from high thermal resistance,this pcb is a bottleneck to the great cooling you supply to make this test.

The pcb you selected to make the test is one of the worst i have tested. Even the round 16mm kd/dx base is performing a bit better(the 14mm cutter and dx/kd 14mm base are worser than both, they have a lot of thermal resistance). I don't have any scientific data like you, but after numerous tests, KD 20mm star or 22mm star from illumination supply are much better. Therefore, you can get better results.You would be amazed if you test a 30mm pcb from an olight M3X.

So,i am pretty sure it is possible to get higher performance and over 1000 lumen with a XM-L. With the excellent pcb olight provides, i am measuring almost 970 OTF with a 4.2amp driver. So, it should be over 1100 lumen on the led.

Next time you would like to repeat this test, take this factor into your account seriously. Again thanks for all this excellent test data and really happy to help you with any way(leds, pcbs etc)

Thank you!

You're correct, there are losses across the pcb. Though, considering a large percentage of the flashlights we use all have the emitters mounted on a pcb of some sort, the test setup here is a bit more apropos to real world conditions than had I reflowed the bare emitter onto the 1" copper rod.

You may be 100% right, or you may be way out in left field :) ... Since I haven't tested or seen data on this particular variable I can't comment and at this point must file it under speculation.

Thank you for the offer of help, and I'm always open to suggestions and input. Unfortunately at this point, I have neither the time nor inclination to repeat this test. I just returned from a 3 week vacation in northern Minnesota and I'm finding it hard to get back into the swing of things flashlight related.

Match,

I feel all LED companies should provide charts like yours. I also wish that there are more drivers available...

Thanks for the graphs, this is the first time I have seen them. This is going to make my flashlight selection a lot easier in the future

Awesome work Match! it's just GREAT!!

Many Thanks for sharing ;)

Awesome job Match thanks

maybe slightly off topic and out of date but is there any test like this with XR-E Q5 emitters as i see alot being driven past 1 amp and all the data sheet,s i see are one amp max i would like to see flux and maybe heat ratings from a Q5 when you push them hard can any one point me in the right dirrection ?

Joining this poorly disguised plea for Match to include the XR-E in this eminent research.

I have a couple of the latter overdriven from stock as well. Laughing