Surefire L4 with Cree MC-E

[Icarus]

Surefire L4 Cree MC-E
· Surefire L4
· Machined reflector
· Cree MC-E M-flux WD-tint (wired 2p2s)
· Custom made heatsink
· Stock driver
· Two-stage switch (McE2S 60 ohms)



Before I actually started modding this L4 the 2p2s wired MC-E with stock driver was tested using my bench supply, primary – and rechargeable cells.

First I tested the setup with my bench supply. The MC-E lit up starting from ~ 4.8V (I out = 40mA). At 6V output current measured 780mA (I in = 1010mA). So, when run in regulation each die of the led sees 780/2 = ~ 390mA. The led is producing plenty of lumens at this level! It also means the 2p2s needs 2 cells. One cell even can't fire it up.

Then I ran the light off two CR123 (primary) cells. As you can see in the graph primaries aren't able to run the light in regulation. Output dropped below 500mA after 32 mins. At 500mA the light is still pretty bright but of course not as bright as when it runs in regulation. After about one hour output drops below 400mA. The conclusion is that you'll get good output for about 1 hour on primaries.

Next I ran the light off two R123 cells (3.7V blue jacket cells from AW). This setup really shines! As you can see in this graph these cells ran the led in direct drive for about 10 mins (because input voltage was > forward voltage of the MC-E). From then on the light runs in full regulation until the protection circuit kicks in. In total I got ~ 32 mins of bright output and was quite impressed! The driver survived the torture of this test without any problem.

It's a pity I didn't have any of AW's LiFePO4 cells (safe chemistry 3.2V) to test with the same setup. I guess these will be better suited because of their lower voltage (but unfortunately also less capacity).

Thanks for reading. :wave:

 

[bluecrow76]

Very nice! Any information current draw using dual stage switch?

 

[Icarus]

Very nice! Any information current draw using dual stage switch?

I'm sorry but the light was assembled before I modded the tailcap switch so I have no idea about forward current on low.
I also can't measure current draw at the tailcap anymore because the light is already with his new owner. :shrug:
Toby, can you help us out on this please?

 

[Illum]

with the stock driver would it operate at all on 1xcr123a?

I've sent my L4 to AaronM to get MC-E'd but as I am using my TW4 I was wondering whether it would operate the same at reduced output
Assuming 2s2p configuration

 

[Icarus]

with the stock driver would it operate at all on 1xcr123a?

I didn't try this light with one CR123A but given the results of my experiments with two primary cells I guess it won't.

 

[Illum]

I didn't try this light with one CR123A but given the results of my experiments with two primary cells I guess it won't.

yeah...primaries looked a bit :shakehead:
I presume 17670s won't have an affect either

I was wondering about your graph for RCR123A...I was told that running 2xRCR123A will damage the KL4 head...I guess they meant burning out the LED, not the driver

 

[toby_pra]

Hi Freddy!

Many many thanks for that nice mod.:thumbsup:

I received the light several days ago and had the chance to test it
in the night. Its more than threetimmes brighter than before!:twothumbs
And its a great wall of light, IMO very useful and nice. I like this
floody beam, but with still enuogh throw...

Sorry i can not tell about the current at the tailcap on low, because
i have nothing to measure it.:mecry: But the low, is a very nice low, not to
bright and not to dark.

I also tested the L4 with 2*Rcr123 and it was friggin bright, but as
Freddy already told, it could damage the driver. And using 2*Rcr123 (with 3.0V)
its very very bright, much more than any little SSC P7 lights i have...



Beamshots will follow later this night!:naughty:

Freddy you did a very very nice and clean work, as always!!! :twothumbs:twothumbs

 

[darkzero]

Awsome mod Freddy. I always enjoy seeing them! :thumbsup: Great information here & thank you for talking the time to put it all together & posting it.

I'm confused, so is the stock driver safe to use with two li-ions? I've always been scared to use two li-ions & still am. :green:

 

[toby_pra]

I'm confused, so is the stock driver safe to use with two li-ions? I've always been scared to use two li-ions & still am. :green:

I think its not safe...even not for longer use. I tested the L4 with
2*Rcr123 (8.4V), for some minutes, it works fine and gets not to hot.
But i will not try it for longer...

 

[darkzero]

I think its not safe...even not for longer use. I tested the L4 with
2*Rcr123 (8.4V), for some minutes, it works fine and gets not to hot.
But i will not try it for longer...

Thanks Toby. :wave:

Freddy stated "The MC-E lit up starting from ~ 4.8V (I out = 40mA). " So does it not run on 1 li-ion?

 

[toby_pra]

Thanks Toby. :wave:

Freddy stated "The MC-E lit up starting from ~ 4.8V (I out = 40mA). " So does it not run on 1 li-ion?

For sure it works with one li-ion...but i think Freddy mentioned, that it is
not as bright, as it could be. But perhaps Freddy can anwser your question better...:tinfoil:

 

[toby_pra]

BEAMSHOTS

Controlshot


Arc6 on high


Novatac 120P on high


Surefire L4-head/E1e-body with MC-E and stock-driver on Rcr123


Freddy's L4 with MC-E and stock-driver on 2*Rcr123 (3.0V)


Both MC-E'd lights are a bright wall of light, but the L4 is a little more brighter...

 

[easilyled]

I was also confused that Freddy said it would only light up from 4.8V upwards and that Iout is only 40ma at 4.8V in the bench test.

This certainly implies that it wouldn't work with one RCR123 which is 4.2V fresh off the charger.

Yet all the other mods like this, that I've seen reported on, seem to work with one li-ion .

From toby_pra's beamshots, there doesn't seem to be much difference in output between the KL4 head mod with E1E body and single
RCR123 setup compared to Freddy's modded L4 with 2 RCR123s.

As a separate point of interest, I suppose results vary according to the Vf of the MC-E.

Freddy, do you know how to predict how much the input voltage has to be compared to the Vf of the MC-E in order for the set-up
to stay in regulation?

 

[rolling]

Can someone do something similar to my L2?

 

[toby_pra]

IFrom toby_pra's beamshots, there doesn't seem to be much difference in output between the KL4 head mod with E1E body and single
RCR123 setup compared to Freddy's modded L4 with 2 RCR123s.

As a separate point of interest, I suppose results vary according to the Vf of the MC-E.

Yes you are right. The L4 is only a lttle more brighter. But more noticeable
in the real world...:tinfoil:

 

[Icarus]

I'm confused, so is the stock driver safe to use with two li-ions? I've always been scared to use two li-ions & still am. :green:

Will, the driver survived the test with two 3.7V li-ions but someone will have to do an endurance test to know if it is safe. In the meantime I advice to use 3.0V li-ions only .

 

[Icarus]

Freddy stated "The MC-E lit up starting from ~ 4.8V (I out = 40mA). " So does it not run on 1 li-ion?

Indeed, this light (MC-E wired 2p2s) doesn't run on 1 (protected) li-ion.
I measured Vf but can't remember and throw my notes away by accident...

 

[Icarus]

Yet all the other mods like this, that I've seen reported on, seem to work with one li-ion.

I suppose the MC-E is wired in parallel in these lights.

Supposed both lights run in regulation then according to my measurements
with the 4p light each die will see 780/4 = 195mA while 780/2 = 390mA for the 2p2s setup.

From toby_pra's beamshots, there doesn't seem to be much difference in output between the KL4 head mod with E1E body and single RCR123 setup compared to Freddy's modded L4 with 2 RCR123s.

Maybe this can be explained because the 4p runs in DD for the first mins (as long as Vin>Vf). Resulting in higher output then when it runs in regulation (195mA/die).

Freddy, do you know how to predict how much the input voltage has to be compared to the Vf of the MC-E in order for the set-up
to stay in regulation?

In this case input voltage had to be close to 6V to stay in regulation.

 

[Icarus]

:thanks: for the beamshots Toby! :thumbsup:

 

[darkzero]

Indeed, this light (MC-E wired 2p2s) doesn't run on 1 (protected) li-ion.
I measured Vf but can't remember and throw my notes away by accident...

When you say "doesn't run on 1 (protected) li-ion" do you mean doesn't run in regulation or doesn't light up at all? This is good info to know if it doesn't light up at all. Do you know if this is an earlier KL4? I don't see why it wouldn't run on one li-ion, it should as just as it should with the LuxV. I've only heard of some KL4s not running on 1 primary (never had one personally) but that probably has to do with LED vf.

All the KL4 MC-E mods (2S2P) I've done do run on one li-ion & are not that much less brighter than 2x123. However all the KL4s I've done with MC-E are the newer style heads with the extra meat in head. Perhaps there are different driver revisions I'm sure. I'll look tonight at a driver from an older head & newer one to see if they look any different.