That thermal “gap pad” is nothing more then a silicone thermal pad, aka those thermal cubes you can get from fasttech, except in a sheet. It is used in place of thermal paste in assembly as it is a lot easier to apply. It doesn’t work quite as good as thermal paste but good enough for most things, particularly if the surfaces are not perfect.
I didn’t watch the video before, ditto all you said, it is all marketing and I would take a Mthlitebar over those anyday. At least he gives us actual data on voltage, power, lumens, throw ect. Plus I trust his lights to actually do what he says because he does give us all that data.
If a manufacture is too ashamed to show that data, then there must be a reason for it.
That said, the BD lights look better then a lot of the ebay junk light bars I see but I would not class them with the Mthlitebar.
Yes the LED will draw current proportional to the output voltage you set that module at. Regarding those DC-DC modules though, I would recommend one with Constant Current capability. There are many varieties available.
The DC-DC modules themselves do make great drivers if you get a CC version. I use many different kinds in various projects of mine, so far they hold up pretty well as long as you don’t drive them too hard.
No. Emitters will draw as much current as you give them. Hook any 12 volt led to a car battery and they will pop. Poof, burn up very fast. In order to control an leds output, you have to control the amperage you give it.
When Cree rates their leds they choose the current. They choose 1.5 amp for the 12 volt version even though it will stay alive at 4 to 5 amps (8 to 10 amps at the lower 6 volts in a flashlight).
So if that module can really supply a full 2 amps at 12 volts to the emitter, and the specs may not be fully accurate, then the 12 volt xhp50 will run at 2 amps.
To see what the lumen output is just look for a xhp50 output test by matchless or djozz. If they test at 6 volts, then look at the 4 amp numbers which is about 3,000 lumen.
I would highly recommend just spending a bit more for a better pre-built light. I have not looked at off-road lights in a long time but I have to believe that someone makes a quality light for a reasonable price.
Or heck, get one of the 12” mtnlitebars and it will blow away anything else I have come across. Something like 30,000 lumens from a 12” bar IIRC. I plan to get one of these when I can afford it.
I guess in theory you could use a flashlight driver that was a buck driver designed to give 2 amps to a 12 volt led. Or a buck driver that delivered 4 amps for a 6 volt led. Set the driver up for single mode use.
That’s not a big amp draw.
The guy that makes the mtn lite bar also runs MTN Electronics. You should send him an email and see if he has a flashlight driver that suits your needs.
We are getting pretty far off topic here, but have you verified your motorcycle has the extra capacity for these lights? Bikes usually has very marginal charging systems and most don’t have any extra output for a constant 2 or 3 amp load. If you add too much load you’ll slowly discharge your battery when the lights are on. Some bikes, like goldwings, have extra capacity built in. What model bike are you working with?
Sorry, that “CD” should have been “CC”. Phone autocorrected, I went back and edited the post.
The CC is useful no matter what because these modules use very cheap and imprecise pots for their adjustment, so every time you feed them power they might start up at 0.2V higher or lower than the original set point. This could cause a fairly large current shift at the LED. As the temperature changes the LED will also draw more or less current at the same voltage.
With CC mode, you are setting the current directly, so it will be constant regardless of temperature or any other factors. It really is the right way to do it. It can be done without a CC module, but you will find the brightness changes depending on conditions, how significant the change is will depend on a number of factors.
Here is just one cheap example of a suitable CC module. At the price there is really no reason not to get one with CC.
Sounds familiar
I posted that in this thread somewhere I think.
Yeah that was direct drive, I thought I had done a bad reflow at first but now I’m not too sure, probably the voltage killed it as I don’t make msitakes
It started off fine, dimmed then the dies went one by one.
Yeah, I see it. 2 months ago. No one commented on it and you thought it was a bad reflow.
Maybe someone who is more knowledgeable than myself will comment about those little cells killing the 50.2.
I would have assumed the low current delivered by those cells would power your light just fine, but if its too high a voltage, then that just sucks. Hopefully Cree will not drop production of the older xhp50 and xhp70.
With the super low Vf of the .2 version of the XHP it doesn’t surprise me. They need a driver and/or some resistance to keep things in check. The 14250 surprises me that it had enough power to pop it but possible I suppose.
Also keep in mind that these LED’s can produce upwards of 80W+ of heat and need a very good heat path to keep them alive.
Voltage itself does not damage a led, it only kills a led when that causes a too high current. The XHP50.2, when reflowed on a DTP board and the heat can get away, can handle close to 15A, and I doubt that 15A will ever come out of a 14250 cell.
I must be something else that killed the led (overheating after all perhaps by a bad reflow?)
You would be surprised how much peak current can come out of a lithium cell.
Many times what is advertised as “max current” if there is no circuitry limiting it.
I can tell you what did my 50.2 in. I used a MTN FET driver with two HG2s. It was reflowed by Richard onto a copper dtp mcpcb. It was only on for a total of 30 seconds and not all at once.
I used the Russian driver mentionned above on my Bandit to feed a pair of XML2 in series at 3A.
It’s been a full year with daily use, no problem even on long ride in the night with high beam always on (I use them with high beam only)
I plan to add 2 more, or swap the XML2 for XHP50, didn’t decide yet
What was the star mounted to or installed in? Did you use thermal paste? Was it clamped down tight?
I recently built a C8 with an XP-L2 and noticed I gained about 100-200 lumens by sanding the threads down to get more clamping force on the star. This can be seen in my thermal tests as well.
the 1405 is not the best design around but it should be enough to keep it alive for more then 30 seconds. You screwed down the retaining ring for the LED nice and tight correct and it was actually pressing the star into the pill?
When building mine I remember that I thought it was tight but the LED started turning blue, turned out the threads had jammed or something and I had to re=install it with a different centering ring to get it to properly press it into the pill.
Although it is possible that the LED just died, these are pretty new and it is unknown exactly how well they handle direct drive. I would personally use PWM to drop the current down some or at the very least some long thin wires. I usually cram as much 24awg wire as I can into the pill to drop the current.
At some point we will get some drivers that can regulate the current for these LED’s but that is still a ways off.
This was my second go with the same build. The first failed within seconds and neither time I remember any blue. The first I chalked up to a faulty LED. I even tried reflowing it and it worked for a second or two to which it died again in quick order. Again I chalked it up to a faulty emitter.
It is my belief intighted it as a much as I can. I can go and verify it was down all the way later today when I’m home. Assuming it was on tight, even with that modest pill the time on turbo would not lead me to believe it overheated.
Based on what I would expect from an overheating emitter I don’t think this is it. I used two high drain 18650s.
