# Surefire L4 with Cree MC-E



## Icarus (Apr 11, 2009)

*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:


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## bluecrow76 (Apr 11, 2009)

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


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## Icarus (Apr 11, 2009)

bluecrow76 said:


> 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?


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## Illum (Apr 11, 2009)

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


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## Icarus (Apr 12, 2009)

Illum said:


> 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.


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## Illum (Apr 12, 2009)

Icarus said:


> 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


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## toby_pra (Apr 13, 2009)

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


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## darkzero (Apr 14, 2009)

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:


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## toby_pra (Apr 14, 2009)

darkzero said:


> 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...


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## darkzero (Apr 14, 2009)

toby_pra said:


> 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?


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## toby_pra (Apr 14, 2009)

darkzero said:


> 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:


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## toby_pra (Apr 14, 2009)

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...


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## easilyled (Apr 14, 2009)

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?


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## rolling (Apr 14, 2009)

Can someone do something similar to my L2?


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## toby_pra (Apr 14, 2009)

easilyled said:


> 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:


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## Icarus (Apr 14, 2009)

darkzero said:


> 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 .


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## Icarus (Apr 14, 2009)

darkzero said:


> 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...


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## Icarus (Apr 14, 2009)

easilyled said:


> 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.



easilyled said:


> 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).



easilyled said:


> 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.


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## Icarus (Apr 14, 2009)

:thanks: for the beamshots Toby! :thumbsup:


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## darkzero (Apr 14, 2009)

Icarus said:


> 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.


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## Icarus (Apr 14, 2009)

darkzero said:


> 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 would 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.


Then there must be different drivers. This one didn't lit up under 4.8V :shrug:


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## mudman cj (Apr 14, 2009)

I have modded some with the old style head (with only two small points of contact from the reflector to the heat sink where the screws attach) and the new style heads with better thermal contact. They all ran great off of 1 Li-ion using the stock driver to the MC-E wired 2s2p. I think I have modded 5 of the new heads and 3 of the old style now. It sounds like you may have a damaged driver there...:shrug:


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## Illum (Apr 14, 2009)

Given the use of a MC-E + KL4 stock driver...the setup will operate on 1xCR123A but I'm not sure about the current draw so I'm not planning to use it as such.

mine anyway, professionally modded by AaronM by special request. 
1x CR123A will work
1x17670 will work
1x RCR123A will work
obviously 2xCR123A will work also
While I'm hoping one day I can try out 2xRCR123A [3.6V cells] but I want to know first the possible damage to the driver maybe

If someone can make a 17670 run it would be very appreciated


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## toby_pra (Apr 15, 2009)

Both lights i have shown in my Beamshots~

~Freddy's L4 and also the Kl4/E1e are wired in 2p2s. The Kl4 works for 
sure with one li-ion. But i did not tried the L4 with only one li-ion
but i am sure Freddy did. :naughty:


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## toby_pra (Apr 15, 2009)

Icarus said:


> :thanks: for the beamshots Toby! :thumbsup:


 
Everytime my friend!


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## easilyled (Apr 15, 2009)

Icarus said:


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



No it seems that the majority of KL4 mods wired for the MC-E are wired 2S2P but still work with one li-ion cell.

I think this is to be expected because as DZ says the old luxV was also wired 2S2P and the KL4 has always worked with one li-ion as well as 2 CR123s.


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## Icarus (Apr 15, 2009)

It surprised me too that the light didn't work with one li-ion.
I'm also starting to think the driver isn't working properly. 
On the other hand it surprises me that the output curve is almost perfectly flat.


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## criollo (Apr 16, 2009)

Nice mod. :twothumbs


Will be sending my Classic Surefire L4 over to Belgium soon. 


Nice beamshots, Toby :thumbsup:


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## toby_pra (Apr 17, 2009)

criollo said:


> Nice beamshots, Toby :thumbsup:


 
Many Thanks...


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## toby_pra (May 7, 2009)

Hello Freddy!

Your inbox is full!!!!:thumbsdow

Did you get my L4-head? :naughty:

Toby:mecry:


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