[Alibaba Adventure] GT-FC40: XHP35 HI's Bigger Sister, with 90+ CRI

This sounds exciting. If everything test out well, perhaps we can get MTN or Kaidomain interested to buy in the quantities they need and we can just buy from them.

The reason I was reluctant to call that a XHP70 HI is that the given spec wasn’t as efficient as the XHP70.2. By estimate it should be about 20lm/w behind at the same CRI.

By the way, just want to let you know that I also plan to later buy these in bulk to make part of the living, and also gain funding to hunt for another product.

No problem with the reduced efficiency. We expect that with all high CRI variants. If you check CREE specs, you can often find that their high CRI versions of emitters are at least one or two brightness bins lower than their low CRI version of the same emitter. In other words, the high CRI version just isn’t available in the highest brightness bins. Same with low CCT (warm) versions. They can’t make them as bright as higher CCT (colder) versions, so the highest brightness bins just aren’t available in the low CCT versions of their emitters.

I see I underestimated the lm/w lost going from 90 to 95 CRI, so let’s see the calculation:

Based on GeTian’s previous product I sampled:

Going from 70 to 90 CRI - you lose 20lm/w
Going from 90 to 95 CRI - you lose another 20lm/w

And based on CREE’s datasheet:

Going from 70 to 90 CRI will cost you 21-25lm/w

Assuming that you lose the same 20lm/w for CREE’s to go from 90 to 95 CRI:

You would look at 70-90 lm/w for the theoretical 95+ CRI version of CREE’s XHP70.2 (or 2200-2900 lm at maximum rated power)

What would be good drivers/flashlights for these LEDs? I only have 3v drivers/flashlights atm so don’t know much about others.

Looking forward to the tests!

I would be very interested in C4 but have a feeling A4 will be more popular.

The readily available driver are the ones that used to drive the XHP35’s, but it’s only driving the LED at 1A so you would be seriously underdrive these LED (though not necessarily a bad thing).

On the other hand, these are 40w LEDs so running these on full tilt in flashlights with poor thermal dissipation could very well be a recipe for disaster.

I created a thread for GB/WTS here:

https://budgetlightforum.com/t/-/58200

Shouldn’t you wait for Djozz test results before posting the groupbuy? Most people are not going to buy without seeing what they are getting.

I should be able to at least do a proper beamshot and side-by-side comparison against CREE’s on a flashlight this week, provided I won’t destroy the driver.

I could always let Djozz chime in later. Djozz’s result should turn up next two weeks.

Also, the manufacturer seems quite confident about CRI values of this thing. They did said something along the line of “see it for yourself”.

I have no doubt it will reach 95CRI however I’m more interested in the tint at different currents and output at different currents.

I guess this week’s beam shot should serve as some kind of appetizer on the tint and output on one specific current. :wink:

I have both of them in a C8s host today.

I got beamshots too. Unfortunately, I only have one high drain 18650, and my setup trips the overcurrent protection of other batteries. I can only give you the individual beamshot for the moment.

All the shots are taken at 5500k WB. I took this with a smartphone camera which annoyingly messes with the exposure setting.

XHP70’s Beam shot

FC40’s Beam shot — Again, This looks much less green than XHP70’s 90CRI, but a bit cooler.

Additionally, the H2-C I ordered are not the same. One of them operates in 1-mode, the other operates in 5-mode. Annoying, but it’s only the best shot I have at this. I probably don’t want to go through the trouble of sanding down the driver and coat it with nail polish again.

Anyway, let’s light up an entire room.

The tint looks great compared with the greenish XHP70.2. Let’s see how output and efficiency test out.

I’ll wait for the test result but sound promising…see the beamshot…I don’t know if this is “going to be next new”…wow, :heart_eyes:

I did some very crude brightness measurement by shining the hotspot on a luxmeter at 1ft distance.

The measurement reads ~120k-140k lux on the highest mode (with the H2-C)

That equals to 11k-13kcd or 210-220m of throw distance in a C8s body

I’m now searching for the proper 20mm driver for these, but it’s really hard to find.

11k-13kcd in a C8 head seems very low.

That could be two things:

  • The nail polish coating isn’t perfect and there might be some low-key shorting which prevents the driver from pushing 1.5A, or prevents the driver from entering the turbo mode. Which I will figure out the way to measure the tail-cap current draw.
  • I might have overloaded the luxmeter and it stops scaling properly past 100k lux (which is it’s stated maximum range, although it continues to register the brightness over 100k lux anyway). I might try to test again from further distance and see what happens.

The hotspot shows much less tint shift than with the XHP70. I’m looking forward to this led in 4000K. Maybe I will use one in a Haikelite SC26.

Update: Light measurement at ~2.5ft (75cm). It seems like my suspicion about the Luxmeter overloading is correct.

XHP70.2 version:

Brightness @2.5ft: 34.5k - 35.5k Lux
Intensity Estimated Output: 20.0k - 20.6kcd
Estimated Throw: 283-287m

FC-40 version:

Brightness @2.5ft: 29.5k - 31.5k Lux
Intensity Estimated Output: 17.1k - 18.0kcd
Estimated Throw: 262-268m

By this setup, it seems like FC-40 produces about 10-15% less output than XHP70.2 (but there is quite a hefty cost moving up CRI from 90, of course)

75 cm is likely still too close. The main reason is that the beam is not fully collimated at short distances. I’m not sure what is the minimum good distance for C8 but if you can measure at 5m I think that should be enough.
Also, what you measure is not output but intensity. I’m nearly sure that at the same intensity XHP70.2 has much higher output.