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Thread: Surefire U2 generations

  1. #1
    Enlightened CELICA XX's Avatar
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    Default Surefire U2 generations

    Is it possible to identify the Surefire U2 by looking at pictures only ?

    Why do some lights say "DIGITAL U2 ULTRA" and others will just say "U2 Ultra" ?



    Which model is newer ?

  2. #2
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    Default Re: Surefire U2 generations

    Color of the threading, number of sides, but most importantly, the serial number.

    The newer models utilize a SSC P4 emitter with white threading, complementing 4 sides on the body. Sadly, they do not fit 18650 cells. That's nothing a little boring can't do.

    If I remember, the Digital U2 Ultra is the one with lux v emitters. Others can correct me if I'm wrong.

  3. #3
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    Default Re: Surefire U2 generations

    Correct, the earliest U2's used a Lux V LED, and an 18650 fits perfectly. Depending on the vf (forward voltage to the LED) an 18650 worked well with all six light levels. The lower the vf, the better for an 18650. Driver uses a boost circuit to achieve 6+ volts, using two CR123's or one 18650.

    Bill

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    Default Re: Surefire U2 generations

    Quote Originally Posted by Bullzeyebill View Post
    Correct, the earliest U2's used a Lux V LED, and an 18650 fits perfectly. Depending on the vf (forward voltage to the LED) an 18650 worked well with all six light levels. The lower the vf, the better for an 18650. Driver uses a boost circuit to achieve 6+ volts, using two CR123's or one 18650.

    Bill
    I wanted to cry when my brother lost the U2A I gave him. He never understood the quality in it. To him, it was just another light--a tool. Mines was an older model that uses 4 sides but a bronze color interrior/threading. It utilizes a Lux V emitter that has a relatively warm tint to it and the infamous doughnut ring in the middle. Sadly, it wasn't old enough to utilize the 18650 cells.

    To the OP, the Digital U2 Ultra are the older models. The newer ones are called U2 Ultra or in short, U2A. It has four sides and utilizes an SSC P4 emitter that is fairly weak with a single cell. Not to mention, the beam is very bluish but perfect.

  5. #5
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    Default Re: Surefire U2 generations

    I still have my old 'Digital U2 Ultra' it takes the 18650 very nicely and I've learned to re-appreciate the warmer tint doughnut hole and all. Truthfully the doughnut hole only shows up during white wall hunting never in actual use. And to many lumen s can be blinding. It has been replace by smaller and lighter SWM V10R/A for EDC.

    =D~~ Kilted

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    Enlightened CELICA XX's Avatar
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    Default Re: Surefire U2 generations

    Thanks guys!

    How has the selector ring held up under long-term use ?

  7. #7
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    Default Re: Surefire U2 generations

    Quote Originally Posted by CELICA XX View Post
    Thanks guys!

    How has the selector ring held up under long-term use ?
    It never failed or stopped working. This guy's built to last just like the rest of SF's LED lights.

  8. #8

    Default Re: Surefire U2 generations

    Just looking around this morning and stumbled across this thread. Being a Surefire U2 owner for several years I was curious about a few things. Is there a way to look up the Serial Number and determine what generation U2 this is and what emitter it has? Mine has Digital U2 Ultra written on the outside, it's a round tube and the inside of the battery compartment is bronze in color. Can I run an 18650 in it? Also what (if any) are the advantages of running an 18650 over two CR123's?

    Quote Originally Posted by CELICA XX View Post
    Thanks guys!

    How has the selector ring held up under long-term use ?
    No issues with mine and unfortunately I cannot remember how old it is (at least 4 or 5 years maybe?).

  9. #9
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    Default Re: Surefire U2 generations

    There are three faces on the ones with 18650 body. The body has a plastic inner tube to hold primary cells. If yours has it, it can easily be removed. If not, see if you have a doughnut hole when used on the white wall. I have a feeling that you have the Lux V emitter version.

  10. #10
    Flashaholic* tobrien's Avatar
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    Default Re: Surefire U2 generations

    thanks for posting this, I assumed the emitters were the only difference
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    Flashaholic* ABTOMAT's Avatar
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    Default Re: Surefire U2 generations

    I have an original Lux V U2 and for a while I owned a U2A. Both held up well under very heavy use. I didn't like the U2A though--the beam was blue with a small hotspot, and the selector ring was biased towards the dim end of things. Like dim1-dim2-dim3-dim4-med-high. Apparently Surefire did this with their SSC P4 lights since I had a Titan that was the same way.

    My old Lux V doesn't last as long on batteries but it has a nice beam (slight hole), warm tint, and perfect brightness levels.

    Quote Originally Posted by JBA View Post
    Just looking around this morning and stumbled across this thread. Being a Surefire U2 owner for several years I was curious about a few things. Is there a way to look up the Serial Number and determine what generation U2 this is and what emitter it has?
    Take a look at the emitter. If it's hexagonal and large then it's a Lux V. If it's square and small it's a P4.
    Do something alone and it's weird, do it with others and it's a club.

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    Default Re: Surefire U2 generations

    Quote Originally Posted by tobrien View Post
    thanks for posting this, I assumed the emitters were the only difference
    Actually there is more of a difference than just the emitter. The Lux V uses a boost circuit, while the U2L uses a buck circuit.

    Bill

  13. #13
    Flashaholic* Eric242's Avatar
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    Default Re: Surefire U2 generations

    I was always under the impression Surefire advertised both the Lux V as well as the SSC P4 version with 100 lumens. At least that´s what my catalogs say (2004 = 100 lumens / 2005 = 80 lumens / 2006 = 100L / 2007 = 100L / 2008 = U2 not listed / 2009 = 100L / 2010 = 100L / 2011 = 100L). Now their web pages says 140 lumens. I assume it´s just a corretion of the SSC P4 (U2A) specs while the light is still the same. Or did the U2 get another update?

    Eric
    Last edited by Eric242; 04-26-2013 at 09:46 AM.
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    Flashaholic* WarriorOfLight's Avatar
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    Default Re: Surefire U2 generations

    I have 4 SF U2, two SSC P4 and two Lux V, both SSC P4 are much brighter than the Lux V and are comparable with lights in the 150-200 Lumens range.
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    Default Re: Surefire U2 generations

    Quote Originally Posted by Eric242 View Post
    I was always under the impression Surefire advertised both the Lux V as well as the SSC P4 version with 100 lumens. At least that´s what my catalogs say (2004 = 100 lumens / 2005 = 80 lumens / 2006 = 100L / 2007 = 100L / 2008 = U2 not listed / 2009 = 100L / 2010 = 100L / 2011 = 100L). Now their web pages says 140 lumens. I assume it´s just a corretion of the SSC P4 (U2A) specs while the light is still the same. Or did the U2 get another update?

    Eric
    Like Eric242, I have the same question. Did the U2 Ultra get another update? Doubt it. There is a product listing for the U2 in the Surefire 2013 catalog, but no photo. Guess I better go ahead and purchase a unit just in case Surefire discontinues the U2 in the near future.
    Last edited by bluebonnet; 12-04-2013 at 04:33 AM.

  16. #16

    Default Re: Surefire U2 generations

    I believe the P4 version has always pushed 140 lumens, and has just recently had the specs updated to reflect that. I highly doubt they've updated the light.

  17. #17
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    Default Re: Surefire U2 generations

    The early (A prefix on serial#) U2 I've had all these years sat around when rechargeable battery flashlights came to light. Since finding out an 18650 works fine in it, been using it some but it just doesn't fit in really well. If only they could replace the head with a setup that could get 800 or so lumens of nice tint. Not going to happen I'm afraid. It is hard to part with it, and it's probably only worth about $100, right?

  18. #18

    Default Re: Surefire U2 generations

    Personally I wish they'd found a way to make the U2 have a Z44 bezel with the anti roll part being the selector ring. THAT would've been badass.

  19. #19
    Flashaholic* tobrien's Avatar
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    Default Re: Surefire U2 generations

    Quote Originally Posted by cland72 View Post
    I believe the P4 version has always pushed 140 lumens, and has just recently had the specs updated to reflect that. I highly doubt they've updated the light.
    good thought
    Quote Originally Posted by cland72 View Post
    Personally I wish they'd found a way to make the U2 have a Z44 bezel with the anti roll part being the selector ring. THAT would've been badass.
    another good thought! haha that would've been legit!
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  20. #20
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    Default Re: Surefire U2 generations

    Quote Originally Posted by cland72 View Post
    I believe the P4 version has always pushed 140 lumens, and has just recently had the specs updated to reflect that. I highly doubt they've updated the light.
    I agree. Surefire is not advertising their 140 max spec as an improved version. The updated spec is printed on the Surefire labeled box.

  21. #21

    Default Re: Surefire U2 generations

    I got one of the first U2's. I did not know it took the 18650 battery until a couple of weeks ago but it fits perfectly.

    My emitter was clocked at 113 Lumens, has just a whiff of green and the faintest of donut holes. The (slight) green is preferable to the overpowering blue tint of some LED's and the beam pattern is just about perfect. The levels are just right too.
    I nearly ordered the updated one but not enough of a difference and the 5 Watt emitter has one of the best beam profiles for my use.

    The U2 really is a special light.

  22. #22
    KITROBASKIN's Avatar
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    Default Re: Surefire U2 generations

    Quote Originally Posted by Minimoog View Post


    The U2 really is a special light.
    Truly it is.

    Just wanted to report that Oveready.com has adapters to fit the SureFire U2, enabling P60 dropins to be used. I couldn't resist and got a glow-in-the-dark triad tailcap with a McClicky switch. Then I went whole hog (almost) and purchased a Cryos Cooling Bezel, which really helps to dissipate the heat coming from the direct drive, Premium Dedomed Tint XML2 with a smooth reflector made by Vihn. It is quite a little thrower, with a beam spread suitable for our landscape here.

    Granted, the U2 body is the only original part being used but I can always go back to the old head whenever, and I like that body, plus the sentimental value...

    The other torch is a 50mm body fitted with a Zero Res Shorty 'switch' in a delrin tailcap and another Cryos Cooling Bezel in the Z32 size. It is a twisty but is easily set as a momentary switch. With another Vinh crafted, thrower dropin this one really shines as well. It is all from Oveready except the bezel ring is straight from Cryos Illumination. Both run on a single 18650 battery and the shock cord lanyard is tied with a Hunter's Bend.

    Respect to All who still appreciate the venerable SureFire U2. Maybe some of you read here on CPF a report that the US Air Force does issue U2's to aircraft mechanics. I think it was on a thread related to military flashlight use.

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  23. #23
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    Default Re: Surefire U2 generations

    Not sure if I mentioned it in this thread, but my awesome U2 that used the four die Lux V, was converted by Vihn to use an XML-U2 high vf LED, and it works just great. Did not quite reach 400 lumens, but fairly close. Works in regulation with an 18650. Uses the stock boost driver.

    Bill

  24. #24
    Flashaholic* Sean's Avatar
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    Default Re: Surefire U2 generations

    For those who have an original stock U2 body that accepts 18650s...will the newer 3400mah 18650s fit as well? (They are a tiny bit bigger)

  25. #25
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    Default Re: Surefire U2 generations

    Quote Originally Posted by Sean View Post
    For those who have an original stock U2 body that accepts 18650s...will the newer 3400mah 18650s fit as well? (They are a tiny bit bigger)
    KEEPPOWER, EAGTAC, ZEBRALIGHT 3400's all work in my old, early model U2.

    Bullzeyebill is indeed fortunate to get his U2 updated. ~400 lumens is really nice! Vinh will not work on them anymore; Says it is too easy to damage them, trying to open them up.

  26. #26
    Flashaholic* Sean's Avatar
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    Default Re: Surefire U2 generations

    Quote Originally Posted by KITROBASKIN View Post
    KEEPPOWER, EAGTAC, ZEBRALIGHT 3400's all work in my old, early model U2.

    Bullzeyebill is indeed fortunate to get his U2 updated. ~400 lumens is really nice! Vinh will not work on them anymore; Says it is too easy to damage them, trying to open them up.
    Thanks for the info. I wonder if Vinh would work on one that was already opened up?

  27. #27
    KITROBASKIN's Avatar
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    Default Re: Surefire U2 generations

    CPF member Nitroz very likely has the most experience modifying the Surefire U2.
    Last edited by KITROBASKIN; 06-02-2018 at 08:17 AM.

  28. #28
    Flashaholic* Sean's Avatar
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    Default Re: Surefire U2 generations

    Quote Originally Posted by KITROBASKIN View Post
    Well I don't have one yet. I'm working on that right now.

    You have good luck with keeppower 3400's?

  29. #29

    Default Re: Surefire U2 generations

    Hey guys!
    Sorry for bringing back an old tread, but I just got a NOS U2 and here seems to be the best one to ask a question.
    I think my U2 is an "odd" generation. It has a Luxeon V emitter, it has a donut at close ranges, the body has three flat sides and says "Digital U2 Ultra". The head threading is yellowish in colour while the body is silver. The body does not fit 18650 and has no black plastic tube inside - its solid aluminium.

    My question is:
    What driver does the flashlight have - boost or buck? Do all LuxV U2s have a boost driver? Can I use a 16650 efficiently in it?

    Thanks!

  30. #30
    Flashaholic* id30209's Avatar
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    Default Re: Surefire U2 generations

    Lucky you!
    Lux V was 6V emitter and i love this version over 3V cause when you swap emitter with Cree XHP50.2 you get instant lumens bump up to 300-400lumens.
    And if you have 90CRI emitter it’s even better.


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