Technical evaluation - Cree XR-E Q4 bin

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I think that the vf comparison that evan9162 made is the difference in H of a lumileds luxeon and a Seoul, both being run at 350mA's to led. They are very close, the Seoul ranging somewhat higher. This would pertain to a lux I, lux III, or Seoul P4 run at 350mA's to the led.

Bill

Hi Bill,

Yes, but not for the Lux III. It is not Vf binned @ 350mA.

Granted I don't have 100 H bin Lux III's and a 100 H bin Seouls to work with, but what I've seen is, @ 700mA, H bin Lux's have a Vf between 3.1 and 3.3 Volts and the H bin Seoul's have a Vf between 3.5 and 3.7 Volts. They may both be "H bins" but, the parameters that determine which bin they are, are not the same. If they binned Seoul's @ 700mA, I'd say the present "H" bins would actually be "J" bins ("K" bin Lux equivalent).

Dave

 

[nanotech17]

evan,
how do you solder the lead wires on both -ve & +ve pads?
it seems the X-RE emitter pads are PITA to solder on.

 

[evan9162]

I just use a 30W pencil iron. I tin the pads and wires first, then just apply heat to reflow the solder on both. It's not really too hard. Make sure your iron is well tinned and clean, with a very sharp tip, and that you're using extremely thin solder.

 

[uk_caver]

I found with a small tip, my iron had problems heating up the tinned wire/Cree fast enough once the Cree had been AA-epoxied onto a heatsink. A larger tip seemed to help me.

Also, I found grinding off the in-place tinning and retinning the copper with my own solder made the process easier. Someone else found that scraping the in-place tinning clean was useful, so maybe it acquires a bit of an oxide coating or suchlike in storage.
I'm sure grinding off is a bit extreme, but with a Dremel to hand, it's as quick and easy as using a knife.

 

[nanotech17]

Thanks all for sharing info.
Appreciate it.

 

[PocketBeam]

Great job evan. I found this very useful. BTW, since I think our collective knowledge is better by sharing I think this thread ties into this very well and is also very helpful. Hope it is OK to post the link here - https://www.candlepowerforums.com/threads/156772

 

[RoGeR]

evans,

I haven't found the datas of tests of Cree XR-E P4 and SCC P4 LEDs. Can you link them?

 

[evan9162]

I have not done a formal report for them. I could easily display them in raw form (like the table above)

 

[Anglepoise]

As said above, it helps to have very thin solder.
However the thiner the solder the less flux, and IMHO flux is one of the keys to soldering. A small bottle of non acidic flux will do wonders for ease of soldering.

 

[mofiki]

Great information on the Q4. Just what I've been looking for because I just recieved three Q4 emitters and the MagD heatsink from the Sandwich Shoppe for a build I want to do, (Bike handlebar light).

I chose to go with three Q4's for the following reasons, (1) I already own a 3021 1000 Buckpuck and Li-Ion 14.8v battery pack from Battery Space and (2) the availability of lenses from Khatod. I ordered three different degrees of field in the tripple lenses because I didn't want three single lenses and reflectors. I got them for free so I'm not out any money too.

My question is; I really wanted to put four Q4's in there but was concerned about the source voltage of my pack and the drops of each emitter and the drop of the Buckpuck - 1.5 to 2 volts. I measured the voltage of the pack and after burning a halogen bulb for almost two hours it still measured 15.2 volts. On a full charge it measures 16.4 volts. Yes it does have a tendency to blow 20W bulbs every once in a while. I understand the emitters can drop up to 3.7 volts each running at the 1000 mA output of the Buckpuck. If you are up to it can you think about this and give me an answer whether or not I could put 4 emitters in the Mod. Also is the bFlex a better driver to use in this circuit?

 

[evan9162]

Lots of things to consider with your setup.

To be absolutely sure, it's best to take the worst case scenario and see if things hold up.

First, the 4 XR-Es - 3.7V x 4 = 14.8V
Next, the dropout voltage of the buckpuck = 2V
Finally, you should consider wiring/contact/switch resistance which could introduce additional voltage drops - that could be as much as 0.2-0.3V

So you're looking at nearly 17V needed for your input voltage.

The 4 XR-Es and 14.8V battey pack is one of those wierd combos where the battery voltage is higher than the load at first, then nearly equal or lower later. In these scenarios, neither buck nor boost drivers are entirely appropriate. A buck/boost driver is made specifically for this scenario - but they are not as widely available.

In this case, you can either just go with 3 XR-Es, which would work with the buckpuck, or get a buck/boost driver which will work both when the battery voltage is higher and lower than the LED Vfs.

 

[mofiki]

Thank you for responding so quickly. Your input really helps. I was hoping to achieve a light that would at least equal the HIDs out there. I will look into the Buck/Boost options and upgrade in the very near future. One more thing, is there any formulas I can use to figure run time with the boost circuit or is it just try it and see. Just thought I'd ask to save me some time.

 

[evan9162]

You can calculate the power input requirement based on the power output and efficiency of the circuit.

So let's say you're running 4 XR-Es in series at 1A, with a total Vf of 14.8V. The load is then 14.8W (14.8V * 1A).

Let's also assume your boost converter is 85% efficient. Now, that is just a ballpark guess, and will be different depending on the input voltage, output current, etc. THis is just a back-of-the-enveolpe calculation.

The 85% efficient means that if it draws 1W, only 0.85W will go to the load. Or, to supply 1W to a load, 1.17W must be drawn from the power supply.

So if we want to deliver 14.8W to a load with an 85% converter, we must draw 17.4W from the power source.

Lets say we're using a 12V battery. 17.4W / 12V = 1.45A. Then you divide your battery capacity in Ah by 1.45 to get the runtime in hours; or divide the capacity in mAh by 1450.

So if our 12V battery has a 3000mAh capacity, then the runtime will be 3000/1450 = 2.06, or about 2 hours.

Remember, the 85% is only going to be ballpark. Efficiency of a converter depends on a lot of factors - the ratio of input to output voltage, the current being supplied to the load, the current drawn from the power source, etc. So it could still vary considerably from the stated value. In the end, the only way to know for sure is to just test it with your desired setup.

 

[mofiki]

OK. I understand that easily enough. I was just wondering the net for a boost driver and you were right. Trying to get something to work with my battery pack is going to be hard to find, if I could even find something. It's any wonder most of the mods I've seen in the forums are just power driven with resistors in the circuit. I just thought it would be safer to have regulation.

As I was looking at the specs of some of the boost regulators one spec caught me and, call me stupid but, confuses me. Max input current. Is that something the user controls by battery choices or what?

I just thought about this too. I also have a Li-Ion 7.4volt 4000mAh pack that is only a couple of months old. I think this might be an option but run-times will suck.

 

[evan9162]

The maximum input current basically limits how much of a voltage boost the converter can supply at a given current level. Since boost converters take a lower input voltage and convert it to a higher output voltage, the current drawn from the batteries will be higher than the current supplied to the load. The larger the voltage differential, the larger the current drawn from the supply. The max input current is a limitation in the circuit that defines how much boost you can get.

For instance, driving 3 XR-Es in series (11.1V) at 1A will require 11.1W. If you use a 6V battery, then your input current will be 2.17A. If your circuit has a max input current of 2A, then it won't be able to supply that power - it will only be able to supply about 10W from a 6V supply.

 

[mofiki]

Thank you. I think I am alot better off now to figure out if I can get a combination that will work. From what I've read maybe this proccess will be easier in the future with the new generation of LEDs, more lumens at less power, hopefully coming out next year.

 

[KevinL]

Evan, thank you for the awesome report and the even more detailed graphs!!

I've read datasheets from SSC that imply 100Lu at 1A, either that or I am reading it wrong: the datasheet is not very clear at all. Your report, which I feel is better presented, shows the SSC P4 is still a solid contender although the Crees have a little bit more light coming out the front.

The advantage of the P4 is that it is easier to work with, having star mounts and readily available reflectors.

I like your bit about 'if you haven't been around in the past year' - that about describes me (18 months actually)

 

[Lightingguy321]

Technical evaluation - Cree XR-E Q4 bin

Sorry for the overly long quote, but what is the bin code on those New Luxeon K2s. Basically my question is, are LXHL-PW14-U000 (UYAN) K2s considered the new generation, or are they stuck along with the older ones?

 

[evan9162]

I really don't see the point in quoting the entire report. It unnecessarily lengthens the thread and doesn't add significance to your question. I would suggest you edit it out.

The "new k2" part number is LXK2-PW14-0160. However, those parts are not available yet.

The best K2s available now are LXK2-PW14-V00.

 

[Lightingguy321]

The PW160 is slated for release in early 2008 right? So where do the UYAN LXHL-PW14-U000 K2s sit in terms of performance?