Ok I see what you’re saying.
I wouldn’t have thought that the efficiency would drop to ~50%, but rather it stays relatively unchanged while heat increases from increased amount of electricity being wasted in the driver (proportionate to the increased drive levels) and of course from the LED.

The efficiency can drop, but not from 90-95% to 50%. I think something would catch fire if that happened.

ryansoh3 wrote:

… If the cells are almost depleted, the driver would try to suck more current for the lack of voltage. This caused my springs to heat up and lose their tension. Copper braiding them helped a lot.

Oh boy I know this too well… this is what fried my TK61 driver running only 5.75A. Getting a new 10A driver from Richard but only pushing it to 7.5A.
I understand that as voltage sag increases (or batteries deplete) the amps will go up to compensate [watts = volts * amps, and the power wants to go as high as possible limited only by driver or power input], but I still don’t understand why efficiency would drop that low.

EDIT:

ryansoh3 wrote:

I do think the efficiency does plummet to around 70-75% or below when modded.

The driver gets ridiculously hot, and the current draw from the cells seem excessive.

From the video, some quick calculations:

Emitter power: 6.0-6.5A x 4.0-4.2V = 24 – 27.3W

Input power: @0:33 3.65A x 10.0V = 36.5W

Efficiency: (24 to 27.3)/36.5W = 65.8 – 74.8%

I guess as supercooling decreases resistance in wires considerably I guess the opposite is very well possible. That makes a lot of sense now.
I remember from year 11 physics it has something to do with the atoms vibrating and flying in all directions causing collisions with each other within the wire, and by cooling them down they flow in a straight line. It would make sense that by increasing the heat energy within the wire it would create more atom collisions resulting in a higher resistance.

Hmm couldn’t hurt to keep it cool. That’s what they do in CPU overclocking – liquid nitrogen cooling but purely for setting records.

The components on the driver were chosen to work at the original output level with a bit of safety margin thrown in, no doubt none of it was designed to still work like stock after the output's been doubled.

The K50 with the higher 4S input voltage to start with will have more room to grow than the other lights with only 3S.

ryansoh3 wrote:

The heating effect may be the cause of the decrease in efficiency.

http://www.cirris.com/learning-center/testing-guidelines/special-topics/...

Quote:

The Temperature Coefficient of Copper (near room temperature) is +0.393 percent per degree C. This means if the temperature increases 1°C, the resistance will increase 0.393%.

If the driver goes from 25C to 125C, the resistance of all copper components will increase by 39.3%. This goes on a positive feedback loop as the driver tries to pull more and more current from the cells.

Now how do we cool down the driver and wires… The only thing I can think of is using larger wires for less resistance and then potting and filling up the driver cavity completely with a good conductive material. It has to be easily removable otherwise you’d have to get a new driver every time you want to make a change. Of course the only pro to this is extended battery life by potentially 20 if it even works, but I doubt it.

Well I jumped in at the very last minute. I had no intentions of even buying the light but out of pure curiosity I sent OL a PM to see what the price was, next thing I knew I was on the list and had been sent payment information haha so naturally the easiest thing to do was buy it!

Anyway, I haven’t seen one of these pulled apart. Are the drivers similar looking to the TN31, K40, TN30 etc? Meaning we can just do the normal replacing of the sense resistors with solder and upgrading of the other bits and pieces?

Slewflash wrote:

Oh boy I know this too well… this is what fried my TK61 driver running only 5.75A. Getting a new 10A driver from Richard but only pushing it to 7.5A.

zeremefico wrote:

Slewflash wrote:

Oh boy I know this too well… this is what fried my TK61 driver running only 5.75A. Getting a new 10A driver from Richard but only pushing it to 7.5A.

Which driver did you got from RMM?

He hasn’t put it on the site yet, but it’s a new driver. He’s putting it in for me

Not sure if this is already common knowledge or not. But I emailed Bella and asked about whether the light was glued together. She said it isn’t.

I also concern about the focusing of the beam after dedoming the LED. Until now there is no any specific method or guideline to do this yet AFAIK, and you have to keep doing it on the trial-n-error basis and by judging the beam pattern on the wall or by lux meter reading.

I read somewhere that if there is a donut in the beam when you shine the light close to something its not focused properly. This happened when I modded my TN31. So I sanded down the centering ring until it was extremely thin but was just enough to locate the reflector still. The beam only has a donut with my hand right in front of the light now. Seems to throw pretty well haha

Have no idea if that is actually how it is done.

LSX wrote:

I read somewhere that if there is a donut in the beam when you shine the light close to something its not focused properly. This happened when I modded my TN31. So I sanded down the centering ring until it was extremely thin but was just enough to locate the reflector still. The beam only has a donut with my hand right in front of the light now. Seems to throw pretty well haha

Have no idea if that is actually how it is done.

Do you have lux measurements of before and after? Most big throwers have donuts until a few meters away. Look at beamshots with defined beams, you can see the outside of the beam is much more intense than the middle part (which would create a donut shining on nearby things).

Definitely black holes are part of the focusing process. You should get rid of the black hole/donut under 1 meter or so. My latest Shocker (best performer) nailed the donut test, like under 10-12 inches or so -- best result I ever got on a de-domed Shocker. Usually when you get a black hole, you have to get the LED more into the reflector.

Slewflash, I’m talking about an actual black spot inside the hot spot on a TN31 beam when shining in a lower mode at a white wall. Unfortunately I don’t have any measuring equipment so no official results. But after sanding down the centering ring as much as possible I only got a black hole starting to form at 18cm ~7 inches when shining on a low mode at a white wall.

From all the modding information and my own experiment I’ve came out a general (unscientific) “conclusion” – we need to make the LED sit into the reflector as much as possible to get the maximum throw, and I’ve seen lux improvement on my modded T08 after I have grinded the reflector base a bit. I know this concept is not applicable to each and every cases out there but it’s just a wild idea.

The TK61 performs best with the substrate below the opening in the reflector. Maybe 3mm? I worked hard on filing the back off the plastic reflector to get the emitter higher into the opening. BUZZZZ! Wrong answer! So I created a spacer out of a copper disc, topped with Kapton tape then also topped with a 3M insulation disc. So yeah, this particular reflector works best with the emitter backed off, not pushed in.

I think I’m going to create a test bench for finding the focus in a reflector using the tiny 10mm SinkPAD, if I cut it down to barely larger than the XM-L2 itself I’ll be able to test focus first, then duplicate that in light.

The hit and miss method is a PITA.

Here is a rig I sometimes use to play with focus.  It's just a scrap piece of 4" (I think) square aluminum (from the scrap bin at Metal Supermarkets) with an aluminum plate (also from the scrap bin) and copper sheet for a pill.  A 4" (I think) PVC pipe has just enough resistance to keep it in what ever spot you slide it to.   It works great. 

I’ll take it!

Have to find a mart and see what I can do….

ryansoh3 wrote:

The TN31 and K40 have identical driver layouts. The TN30 has a nominal output voltage of 9.0V for the three XM-L2’s in series. Not so sure about the K50, I’m curious as to how far we can push it. I do have a gut feeling that bridging the sense resistors will be too much for the LED. (> 9.0A)

I bridged a sense resistor on a TN31 and without putting on heavy wires it was fine. I’m guessing if I had put super heavy wires on I would have been in trouble.

On TN31's, I measured as low as 5.5A to the LED with bridged resistors and maybe 22 AWG, but I measured 6.2A to the LED with 20 AWG I believe, and I think 18 AWG is used to get the 6.5A to the LED.

Tom E wrote:

On TN31’s, I measured as low as 5.5A to the LED with bridged resistors and maybe 22 AWG, but I measured 6.2A to the LED with 20 AWG I believe, and I think 18 AWG is used to get the 6.5A to the LED.

Thanks Tom. That’s great info right there. Something to keep in mind for sure.

I replaced the resistors with solder on my TN31 and used 18awg wires. Works perfectly.