Princetontec Yukon HL - Low power mode isn't.

Princetontec Yukon HL - Low power mode isn\'t.

Just received my Yukon HL headlamp, and decided to take some measurements on it- it draws 420mA at 4.5V on the high output setting, and ... 530mA on low.

Since the three LEDs draw more power AND put out less, there seems to be little incentive to use that mode- I don't plan to use it, especially with the decidedly blue tint they put out in comparision. I consider it a rather worthless mode-
At lower input voltages, it swaps places, where the three LEDs draw about the same as the single Luxeon, and at near discharged levels, they draw about half (25mA vs. 43mA), but nothing like the ratio indicated by the suggested 25 hour vs 120 hour ratio.

Re: Princetontec Yukon HL - Low power mode isn\'t.

I wrote to PT and asked them what the current draw in mA is for the two different modes. I'll post the reply here.

Re: Princetontec Yukon HL - Low power mode isn\'t.

530ma for 3 LEDs! No wonder Yukon HL's 3 LED is way brighter than all other 3-LED lights I have /ubbthreads/images/graemlins/ooo.gif

BD Zenix seems have the same problem even on 2 LED.

Alan

Re: Princetontec Yukon HL - Low power mode isn\'t.

I don't know the unit in question, but I know that a lot of LED based products use PWM (Pulse width modulation) to dim the output. If that's the case, could the PWM be messing about with the reading on your meter (I had one that used to give totally spurious readings in such a case).

Re: Princetontec Yukon HL - Low power mode isn\'t.

No evidence of PWM with the Yukon HL- waving it around furiously shows a steady output; probably directly driven.

Re: Princetontec Yukon HL - Low power mode isn\'t.

I don't have the HL, but I've taken apart the regular Yukons. They only have resistors.

That much current to the 5mm LEDs sounds unbelievable to me. Are you sure your meter isn't screwed up? I have a digital one that gives weird readings if the batteries aren't fresh.

Re: Princetontec Yukon HL - Low power mode isn\'t.

It's the input current, not a measurement through the individual LEDs- I was just measuring the current being supplied with a 4.5V drive. Keep in mind the batteries will not maintain 4.5V either; I was using a power supply to drive it at a constant 4.5V (voltage directly measured at the terminals of the light, so the insertion of the series resistance from the DMM ammeter doesn't matter).
If you make the measurement using batteries, the current will be lower- what values have you been seeing?
In any case, the difference in the draw between the high and low modes doesn't at all indicate a 120 to 25 ratio.

Re: Princetontec Yukon HL - Low power mode isn\'t.

Wingerr,

Sorry, I didn't read your first post carefully enough, and glossed over the "at 4.5V" part. I thought you were just using batteries. I don't believe the 120 to 25 ratio would be very accurate (PT is no exception to bogus runtime claims). An underdriven LS can have comparable runtime to 3 overdriven 5mm's. I get around 200ma on fresh NiMH for the 5mm's. I imagine the LS isn't designed to draw much more than that.

Re: Princetontec Yukon HL - Low power mode isn\'t.

What input voltage do you measure for the 200mA reading you get? I can drop the supply voltage to get 200mA, and find out what voltage it needs; I'd like to see how close they are to some others. It could be that my sample is just out of the norm.

Re: Princetontec Yukon HL - Low power mode isn\'t.

I measure 4.1V across the batteries.

Re: Princetontec Yukon HL - Low power mode isn\'t.

I had measured around a 270mA draw for the leds and 280mA for the luxeon. I wrote to PT to ask them about this, and here is their response:

David,
The three Nichia LEDs will draw as much as 300mA with fresh batteries and the Luxeon will also draw somewhere around 250 to 350mA. There is a difference in the quality of light between the two, the Nichias being a wider beam and the Luxeon being more focused. Since this light uses passive regulation (resistors), the current draw will depend on the particular characteristics of the LEDs that are installed and the batteries' state of charge. Different units of the same LED model can have significantly different current draws at the same voltage. That characteristic is the result of minor variations in the silicon wafer used to create the chips and is common to all LEDs to varying degrees. The difference in the published run times is more a result of the way we have been measuring run time. Our measurement standards have been evolving over the last two years. The run time of the Luxeon is the average time to a luminous flux of 1/4 lumen. The run time for the Nichia LEDs was to a more subjective "can I find an object in the bottom of my backpack" measurement. In both cases, actual run time for any individual unit may be longer or shorter than the estimate because of variations in the individual LEDs in the unit. If you have any other questions or comments, please feel free to contact me again.

Thanks,

Jay Harrington
Customer Service Representative


I'm kind of disappointed. Other than a quick change ability for spot/flood, the HL is draining the same amount of current for both applications. Might as well go with the luxeon, no?

Re: Princetontec Yukon HL - Low power mode isn\'t.

Yeah, to me, the three LED mode brings little to the table; it's bluish, and draws more power than the Luxeon with fresh batteries. At the lower voltages, it will draw less, but not enough of a difference for me to want to use it, especially since it's so much dimmer for any given voltage.

Measured the following:
3 LED mode: 4.10V 260mA, 4.5V 500mA


Luxeon mode 4.10V 300mA, 4.5V 400mA

Current reading is more in line with Lex's reading, with the lower drive voltage.
It might not be a good thing to drive it the way I've been doing; it may assume there's voltage droop from batteries to keep from overdriving the LEDs.

Either way, the Luxeon output is totally white on mine, with no detectable tint, and the 3 LEDs are quite a bit dimmer and bluer that I think I'll be bypassing the mode every time I use it- Kind of a hassle to even have the mode now, since I'll need to click it multiple times when I use it. Oh well-

Re: Princetontec Yukon HL - Low power mode isn\'t.

Ok, It's mod time!

Can you open the light, and route the wire that feeds the 3 LEDs through a resistor to the luxeon? If so, you can pick a suitable value that will under drive the luxeon, cutting current and giving a softer light.

I like around 100ma for a low beam. It's 1/4 the power consumed but still quite usable.

Daniel

Re: Princetontec Yukon HL - Low power mode isn\'t.

I thought I might open it up just to peek around, but removal of the two screws inside the housing didn't easily release it like I was hoping, and I didn't want to get too agressive with it just yet.

I'd be inclined to maybe try reconfiguring it to just put the three LED's in series with the Luxeon for the low power mode, to accomplish the voltage drop without wasting it as heat. Get the three LEDs to work for their money too- /ubbthreads/images/graemlins/smile.gif
Anyone figure out if it can be cracked open without destroying it?

Edit: Already asked here

Re: Princetontec Yukon HL - Low power mode isn\'t.

I'll have to try that. 3 Nichias and a Lux. Hmmmmmm

Re: Princetontec Yukon HL - Low power mode isn\'t.

i opened a couple up and even removed the luxeon " Everled " without much difficulty...don't have them anymore but its doable without any special tools and i did not damage the unit(s),,,and was able to put them back together.....rob

re: Princetontec Yukon HL - Low power mode isn\'t

Was the switch just a simple SPDT setup? Should be easy enough to try if it uses discrete wires for the connections-maybe I'll give it a try..

ed:
It looks like the seam for the case is glued together though, so it'd need to be cut through to open up. I'd rather not do that, so I'll leave it be for the time being.

Re: re: Princetontec Yukon HL - Low power mode isn

Wedge a razor blade in the seam, and rotate it around the whole seam.

The switch is simple SPDT with discrete tab leads (solders into PCB, which is needed to keep the switch in place). If you're inclined, you could also add a sliding switch in the case for more resistance, and maybe a defeat mode for carrying in a pack or glove box.

Re: re: Princetontec Yukon HL - Low power mode isn

I still haven't tried to open it up, since it involves cutting it up, but now that it's sat around for a sufficient time (though I just put it back in the box after I tested it), I may go ahead and try it, since curiousity is getting the better of me.
Before I do, has anyone tried the series reconfiguration to see what it does? If it's confirmed worthless, I'll leave it in its virgin state..
I suppose this could be tried with any set of Luxeons and 5mm LEDs, since that should yield the same results. Anyone able to try that?

Re: re: Princetontec Yukon HL - Low power mode isn

Last one I cracked open was tougher, and I messed up the gasket a bit in the process. Not sure if they're using different glue.

I would think a Lux with a 5mm in series would present too high a Vf, unless I'm missing something.