Testing my modded lights

[dazz]

@EasyB

No problem, glad the circuit seems to be working and making sense.

That LED you linked is still an XPL version 1. Int-outdoors doesn’t seem to have XPL2s. Here is one:
http://www.kaidomain.com/p/S026462.Cree-XP-L2-HD-Neutral-White-5000K-LED-Emitter-with-KDLIGHT-3535-20-20mm-x-1_5mm-DTP-Copper-MCPCB

Nice, thanks for the emptienth time

[dazz]

@Rufusbduck

You might be able to switch to a better FET. Rds-on which is the internal resistance of the FET at a given gate voltage varies significantly and is the main criteria for choosing a particular FET. Cheap drivers use cheaper fets which start showing higher resistance sooner on the discharge curve. One of led4powers drivers with the sense resistor set to 2.5A should perform better.

I’ve done a bit of research on led4power drivers and they look great. Do they have an online store?

[Rufusbduck]

Yes, Led4power LD-3 he’s on version 3 now and a member here at BLF.

[dazz]

@Rufusbduck

Yes, Led4power LD-3 he’s on version 3 now and a member here at BLF.

Thanks. So the LD-25 is also a led4power driver?

[dazz]

Wow, I’m so impressed with this LD-3 driver. It has everything I’m looking for and more. The configurability is simply AWESOME!
I’ll be ordering the 3A version, so here’s another question please. The efficiency at 6A based on HKJ’s review is about 95, while the 1.2A medium mode starts at 70.
So at 3A, would you expect the initial efficiency to be closer to 95% or 70? The LD-25 starts at 80 (4.2V in) so this LD-3 is probably much more efficient, but how much?
Also, I take it it will work just fine with both XM-L2 & XP-L2, right? Will the lower Vf of the XP-L2 be an issue for efficiency when coupled with that LD-3, considering that it stays in regulation for much longer?

[dazz]

@Rufusbduck

You might be able to switch to a better FET. Rds-on which is the internal resistance of the FET at a given gate voltage varies significantly and is the main criteria for choosing a particular FET. Cheap drivers use cheaper fets which start showing higher resistance sooner on the discharge curve. One of led4powers drivers with the sense resistor set to 2.5A should perform better.

Oh, I think I finally managed to parse that. So you were essentially saying that replacing the mosfet for a better one, one with a lower “ON resistance” could improve the driver’s performance.
This is the mosfet in the LD-25 http://www.onsemi.com/pub/Collateral/NTD70N03R-D.PDF. What would be a good replacement?

[dazz]

OK guys, so I followed your lead and I’m very happy with both the LD-3 driver (really awesome) and the XP-L2 HD emitter (Vf @ 3A measured at 3.24V vs 3.55V for my XM-L2) in terms of performance
The only issue is that the XP-L2 HD is smaller and seems to be out of focus because it’s producing an ugly tint shift between the hotspot and the spill, where the spill is much warmer. In short, The hotspot looks good, the spill is noticeably warmer, and the flood (the outer portion of the beam) tends to cool white.

I’ve been googling for a solution but couldn’t find anything. I think getting the emitter a bit further down would improve focus, but I may lose output in the process. Are there XP specific reflectors with a smaller emitter hole?

Thanks in advanced