Strange Surefire U2 problem with ring

[Kiessling]

This is the problem ... we do not know, and most likely won't ever.

When looking at the long term experience on CPF we can assume that the U2 (LuxV) does work with Li-Ion.
Now ... SF changes their products and upgrades them without notice. Another thing to consider. Again, we don't know.


kromeke, I am really not an expert and I have no clue about electronics and things. I am just a long time on CPF and have learned and seen some things. One example is converters frying on a LuxV and Li-Ions where they are fine on CR123. It happened after a chip manufacturer changed some little details in their chip, and now the driver couldn't handle the current any more and died. All this was hypothetical, too, but the chronology was there and the drivers were dead.

bernie

 

[kromeke]

kromeke, I am really not an expert and I have no clue about electronics and things. I am just a long time on CPF and have learned and seen some things. One example is converters frying on a LuxV and Li-Ions where they are fine on CR123. It happened after a chip manufacturer changed some little details in their chip, and now the driver couldn't handle the current any more and died. All this was hypothetical, too, but the chronology was there and the drivers were dead.

Yes. And I'm no expert in electronics as well, but I have had a few classes and many years experience playing with circuits. I know enough to be dangerous, as they say.

And yes, SureFire has shown that they do revise designs and that everything they do is subject to change without notice. That is fair and their right as a manufacturer. They are also dependent on component manufacturers who can also make changes without notice. If you play with fire, you might get burned.

Sorry about the OP's U2. Personally, I think it was a bit soon to start playing with li-ions in a brand new product. If I've learned anything about electronics, it is that they often suffer from what industry calls "infant mortality" in the sense that the product may pass tests and get delivered, only to fail soon after it is in the hands of the consumer.

In this case you have a lot of variables. New light, possibly changed from previous versions of the same light, good behavior from non-supported cells, followed by odd behavior from supported cells. Something went wrong somewhere, if this is all the case. Did the light have a latent defect, which might have appeared regardless of the choice of power supply, or did the use of non-supported cells lead to a failure? Don't know. :shrug:

 

[ja10]

One thing is often astonishing. This is how easily people betray others. Abusing a generous warranty ... laying the burden for one's own mistakes on all shoulders that buy SF lights.
I am surprised at how common and accepted such a practice is here.

bernie

I'm not sure if this is in response to my comment or not, but in case it is, I wanted to clarify. I agree with you. If I mod or alter a light, I will take full responsibility for any failures. With the U2 though, there are some people who have flat-out said they used li-ions and they were still covered. Other's weren't. With the track record of li-ions in U2s working so well, I don't mind not volunteering that bit of info, unless specifically asked. But maybe that's just me.

 

[dogone]

Mine is a early model, and accepts 18650 cells with no modifications. It is also a Lux V model.

One question: do you have the new model U2, the U2A with the SSC P4 emitter? Maybe they still have some bugs in production?

Mine is an old style U2; but no plastic insert; tight fit for Pila 600s; 18650 out of the question.

 

[Bullzeyebill]

Mine is an old style U2; but no plastic insert; tight fit for Pila 600s; 18650 out of the question.

So it is a Lux V, the last version that was setup with a narrow battery tube, but no plastic insert. Unusual problem you have, and not sure that Li-Ion has caused any problems. U2 is boost only. You can use a magnet on the negative end for added length, but get one that is large in diameter so the tailcap spring has a good surface to make contact and that fits on the metal part of negative end only, you do not want it to contact the battery tube. Be careful about thickness of magnet so as not to crush the four little legs in the tailcap switch that make contact with the rim of the battery tube. If legs become too flatened they will not make contact, though you can fix that problem by prying the legs back up a little. http://www.kjmagnetics.com/ has magnets in all sizes.

Bill

 

[dogone]

Thanks for the advice on the magnet. I don't seem to have the 4 legs in the tailcap you and others have described. Instead there are three copper tabs at the rear end of the tailcap that make contact with the battery tube when screwed in all the way.

 

[NoFair]

Thanks for the advice on the magnet. I don't seem to have the 4 legs in the tailcap you and others have described. Instead there are three copper tabs at the rear end of the tailcap that make contact with the battery tube when screwed in all the way.

The problem with 17670s is usually that the + end of the battery does not have a button like a cr123 and though will not contact the spring in the head of the light. The length of the cell is not the issue even with the slightly shorter 18650 cell.

You stretch the spring in the head of the U2 a mm or two, this ensures good contact. Note that this disables the reverse polarity protection.

I think the first U2 were actually intended for use with 18650s due to the fatter tubes. Lots of CPF'ers have been running their U2s on 18650s.

I'd try cleaning all contacts surfaces, using 2 cr123s and trying a lot of mode switching. If that doesn't help contact SF and get an RMA.

Sverre

 

[Superdave]

has anyone taken apart the regulator setup and repaired it?

the heatsink appears to be thermal epoxied into the ring housing, it shouldn't be that hard to get out... Of course this would void your warranty but for those of us who have allready voided it, it shouldn't be an issue if you have the knowledge and right repair equipment.

Mine never had anything but SF cells or was hooked up to a digitally regulated benchtop power supply to monitor current draw and never saw anything above 6V and yet the levels are still messed up. It could have been the Q5 Cree shorting to the reflector for a split second but i doubt it.

 

[Henk_Lu]

First of all, bad analogy. Diesel costs more anyway.

One question: do you have the new model U2, the U2A with the SSC P4 emitter? Maybe they still have some bugs in production?

Sorry, I forgot this is an US forum...

In Europe, Diesel is still cheaper, in Luxembourg e have about the lowest prices around (only Spain is still cheaper), an a liter (not a gallon...) of Diesel is currently about 85€-cents, fuel is about 10€-cents more expensive.

I have the old U2 btw, Luxeon 5 with the narrow battery tube.

 

[Bullzeyebill]

Thanks for the advice on the magnet. I don't seem to have the 4 legs in the tailcap you and others have described. Instead there are three copper tabs at the rear end of the tailcap that make contact with the battery tube when screwed in all the way.

You have the latest version U2 tailcap. I have one of those in addition to the original tailcap, and the three tab tailcap does not want to screw down all the way like the original model. Keep your eye on it. Yesterday I found that adding one coil of a spring on top of those tabs allowes the tailcap to make contact with the rim of the body. A loose fit, but works for me. I think that by taking the tailcap apart I might be able to pry those tabs higher, not an easy fix, like the original tailcap where you can pry the four tabs up.

Bill

 

[iapyx]

Sorry, I forgot this is an US forum...

Is it? Now I would like to know.
And we in Europe all know that in Luxembourg the fuel is the cheapest (as diesel is in Spain), you lucky *******s! That's why we make detours on holidays down south to buy your cheap fuel.

to keep this thread on track: I've used AW li-ions in my U2 for two years w/o any problem. And yes: with one magnet to make contact.

 

[kromeke]

I considered that it might be cheaper elsewhere, but I wouldn't have expected it in Europe. Don't you guys have low sulfur requirements there as well? With the advent of low sulfur diesel, I thought would be expensive everywhere (where they use it)

Back to the U2:
Hasn't there been reports of problems with the selector ring in the past? Nothing widespread, but the occasional bad ring?

What is the current status of the OP's U2? Does it continue to work fine on the Li-ion cell (The Pila) but not with 2x 123 batteries? Or have you lost a few levels in general?

 

[dogone]

3 levels (lowest, next and then maybe level 4) with the 123s and nothing at all with the Pila.

 

[Bullzeyebill]

3 levels (lowest, next and then maybe level 4) with the 123s and nothing at all with the Pila.

Ok, try dropping a relatively thin piece of round spring, one coil only, or a wire you can shape to fit to lay on those three copper pads. Wire should overal at least two of the pads. Wire should also be of sufficient overall diameter to pass over the + spring tower, sort of about the same diameter as the rim of the battery tube, maybe a little bit larger. Then screw down the cap again gently until it stops. You should have very good electrical contact at that point. This will rule out the tailcap as a problem.

Bill

 

[dogone]

I think I can rule out the tailcap: Screwed down all the way the light works on the all the levels it has; unscrew it about a half turn and the light goes off no matter what level chosen on the ring.