Testing a Cree XHP50.2 J4 3A led

I want to ask if someone tested the nano MCPCBs from fasttech (https://www.fasttech.com/products/1609/10031707/7156107)? What i can find on the net if i search for nano MCPCB sounds promising (http://www.camnano.com/nanotherm-lc/?gclid=CMuynYPo2NMCFaoK0wodHMUOzw) but i do not know if the pcbs are from this supplier or have the same specs.

Noctigon or SinkPAD XM-L mcpcbs, tried and true.

The issue with LED lights is more about heat then anything. We are pretty much always heat limited and it appears that you would be as well in those lights.

They should handle 1.5A @ 6V fine (about 10W of power) fine from how those lights appear to be made.

You can drive these LED’s up to 10A+ if you can keep them cool and they will make ~5000 lumens each at that level if you do.

Although I am not sure what you mean by 100% efficiency. There is no such thing with LED’s. If you mean the max efficiency then you would only want to run them at like 100ma. efficiency drops as power goes up, see some of the tests we have posted on here for examples.

They will still be pretty efficient up until around ~6A though, so that is not a problem in your case, the issue is once again keeping the heat in check.

That link is just advertising. There are no actual details or specs on it from which to derive any useful data.

It appears they use a DTP copper mcpcb which is great but also no different then any other copper DTP mcpcb on the market. Also they say 100% power, not efficiency. Big difference. 100% rated power for the xhp50 from cree is like 2.8A. There is no such thing as 100% efficiency as the lower you driver it, the more efficient it will be.

We run the xhp50 up to 8-10A in flashlights but that will quickly overheat in that light you have. 1.5A should be about right I figure.

You can run the LED in 12V mode but better off in 6V mode, that will ensure it stays in regulation and that you can use a cheap XM-L DTP copper star.

Are those lights you linked to already LED? It might be easier to either just swap the LED’s in them or mod the driver for a bit more power. Got a link to those lights?

Hi stormrider88, Welcome to BLF!!

The BD "Mad Scientist" guy sure is funny. Talks like he discovered or invented copper for LED thermal management, something we've known and practiced for years. Also several of the major LED high performance flashlight manufacturers have been doing copper for years as well, like Fenix and ThruNite.

That BD site though says 100% power, not 100% efficiency. I think that's mis-leading what's goin on there.

It's a shame because he's dis'ing a lot of us out there, including Richard at MtnE who sells light bars here: http://www.mtnlitebar.com/, who I'm sure is using copper in the LED MCPCB's.

The "Thermal Gap Pad" thing is interesting though. Wonder how efficient that is...

Edit: Ooops cross posted with TA.

+1 with TA!

I can help with that last part.

The xhp50 and xhp70 are available in both 6 volt and 12 volt versions. Each emitter has 4 tiny dies which are 3V each.

So the 12 volt version have all 4 dies wired in series.

The 6 volt versions have the dies wired 2 in parallel and those 2 in series.

So 3 amps at 6 volts equals 18 watts.

1.5 amp at 12 volts also equals 18 watts.

Same power levels.

Watts law states volts X amps = watts

Make sense?

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?

I’m glad you did the research. :+1:

Some folks just add stuff and then wonder why their stator coil burned out or why their battery is always low. :person_facepalming:

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.

I was just reading on another thread that a fella burned up his xhp50.2 using 2 little 14250 cells in series.

Does this surprise anyone here?

Comments on thread starts here and go down:

Sounds familiar :slight_smile:
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 :smiley:

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.