Strange Surefire U2 problem with ring

[dogone]

I just received a brand new U2 today. It worked perfectly. 6 evenly spaced gradations of light. Tried my new AW17670 batteries- Nothing. They seem too short. Tried the Pila 600S- very tight fit but it worked great. Swapped back and forth a few times trying to get the AW17670's to work. Then frustrated put the new (15 minutes on them) Surefire CR123's in. Now only 3 levels dimmest, second level then a jump to maybe 4 and nothing more. Tried new Duracell 123s - same thing. Anyone here have this experience? I will call SF and expect OK service based on comments on this site.

Thanks for all the advice on the SF and rechargeable batteries posted here. Think I will end up looking for spacers to make the AW 17670s work-- magnets?- because they slide into the tube much better.

 

[greenLED]

FYI, using li-ions in SF lights voids their warranty.

Unless you used 2x123's, I don't see how the modes would go on you.

Are you sure those 123's you put in there are fresh? Usually when batts are low, one loses the higher levels.

 

[socom1970]

DO NOT tell them you used Lithium Ions in it. Ever. I would put in known good cells. New ones that test very good. Otherwise, SF CS will take good care of you.

 

[dogone]

These were new Surefires and new Duracells from Flashlightz.com. No rechargeable RCR123s, just the 17670's and Pilas tried as well. The Pilas workedgreat but were a tight fit. The 17670s fit well but need a magnet spacer.

 

[McLux]

I was wondering a time ago if the U2 can work with li-ion for a longer time :
A luxeon V with a Vf of 7.5 V and a current draw of 0.7 A gives 5.25 W.
If you feed it with 2 CR123 (6 V), and a circuit efficiency of 90%, the input current is 0.97 A. If you feed it with a li-ion with a voltage of 3.6 V, the input current became 1.62 A.
If the circuit is designed for 1 A, it is possible it will break down after a while.
There are runtime tests of the U2 with li-ion, so maybe it can handle the extra current without problems.

 

[Henk_Lu]

I don't know what can have happened here, I'm not into Li-Ion rechargeables, they are hard to get here in Europe, and, reading some threads, I understand why. Those cells can be dangerous for your lights (or other devices) and for yourself if yu don't know exactly how to handle them. So, I decided to stay with primaries.

Thus, I don't understand why somebody buys such an expensive flashlight as the U2 and gives itthe wrong fuel. The manufacturer must know why he doesn't allow rechargeables, doesn't he? I know that if my car needs fuel and I try to save money by putting diesel in it, I will kill expensive parts of the engine, so I don't even think about it.

If one day I'll decide to get some 18650 (the only ones you get easy around here), I will only use protected ones and only stick them in those lights where the manufacturer tells me I can!

I hope you get your U2 to work properly again!

Greets,

Henk

 

[dogone]

Some clarification: The AW 17670 (unprotected) never made contact as they are too short. The Pila 600S is a protected cell that many members here have had lots of success with. I have read of no prior reports of people having problems with either unprotected 17670's (presumably with a spacer) or the Pila 600s or 168s (virtually same item). This is why I took the "risk".

The manual with it is labeled Revision A 11-1-2004 so maybe McLux has the right theory.

Regarding SF policy and rechargeables: there is NO MENTION of any warning or voiding of warranty anywhere on the box, manual or any of the other pieces of paper that came with the light. There was a WARNING READ FIRST about heat and combustible safety on the back of a Great Price For The Best Battery offer. NOTHING ABOUT USING RECHARGEABLES OF ANY KIND!

 

[Carpenter]

On their website under warranty, it states the warranty is void if anything other than SureFire batteries are used.

I admit, most companies say to use their stuff and nobody elses, but I read this line to say use the batteries that are called for (CR123's) and not Li-ION's.

Normal wear and tear — including lamps burning out, batteries draining, and switches wearing out — is not covered, nor is damage resulting from abuse, neglect, battery leakage, use of other than SureFire-brand batteries or accessories, or altering this product from its original state.

 

[ja10]

I wouldn't worry about Li-Ions. I used nothing but 18650's (protected and unprotected) in my U2 for 2.5 years. There were no problems.

The U2 and Li-Ion issue has been pretty well vetted here. There are TONS of U2s using them with no problems. It goes beyond a few runtime tests.

I would call SF, but like someone else said, don't mention the Li-Ions. I understand that some people have said something and still got their light fixed, but others had their serial number blacklisted, and SF wouldn't touch their light. Do whatever you feel is best though.

Good luck getting your light up and running.

 

[dogone]

Thanks Ja10. I won't mention them.

 

[ja10]

I don't know what can have happened here, I'm not into Li-Ion rechargeables, they are hard to get here in Europe, and, reading some threads, I understand why. Those cells can be dangerous for your lights (or other devices) and for yourself if yu don't know exactly how to handle them. So, I decided to stay with primaries.

Thus, I don't understand why somebody buys such an expensive flashlight as the U2 and gives itthe wrong fuel. The manufacturer must know why he doesn't allow rechargeables, doesn't he? I know that if my car needs fuel and I try to save money by putting diesel in it, I will kill expensive parts of the engine, so I don't even think about it.

If one day I'll decide to get some 18650 (the only ones you get easy around here), I will only use protected ones and only stick them in those lights where the manufacturer tells me I can!

I hope you get your U2 to work properly again!

Greets,

Henk

The reason is pretty simple. The U2 is a regulated light. It has a boost converter, so it can take up to 6 volts or so and somewhere down to the 2 volt range. When there isn't enough juice left, it starts dropping off the high modes.

You might be starting with a fresh 6 volts with new 123s, but what happens when you use the light? The voltage drops. I don't remember when the U2 quits working, but those cells can drop down to the 1-1.5 volt range in other lights. That leaves you with 2-3 volts coming out of the batteries.

If the U2 couldn't handle the lower voltage of the Li-Ions, it couldn't handle drained 123's either.

Also, just to make one more correction - Li-Ions aren't that dangerous. The thing to remember is that you don't want to over charge or over discharge the batteries. Get a smart charger and use protected cells, and you're fine.

 

[dogone]

Maybe I have a bad batch of new Duracells but I never got anything higher than level-3-4. The dropoff was WAY fast with the Surefires. No more than 5 to 10 mins max at the high setting on the new Surefires. Anyone would have mentioned this reviewing the light because it would render it completely unusable.

 

[asdalton]

You should call Surefire customer service (phone, not email) to arrange to return the defective light.

There's no way you would have damaged the light by using one Li-ion rechargeable cell in place of 2x123A.

 

[kromeke]

Thus, I don't understand why somebody buys such an expensive flashlight as the U2 and gives itthe wrong fuel. The manufacturer must know why he doesn't allow rechargeables, doesn't he? I know that if my car needs fuel and I try to save money by putting diesel in it, I will kill expensive parts of the engine, so I don't even think about it.

First of all, bad analogy. Diesel costs more anyway. The SureFire branded batteries clause in the warranty statement is a crock. That is like saying I have to use Ford oil in my Ford and Honda oil in my Honda.

To turn that around, I don't know why SureFire can produce a light as expensive as the U2 and have it not accept off brand batteries.

If you installed a single li-ion cell @ ~4.2v max it cannot damage the light. Otherwise, how does the circuitry know the difference between a Li-ion cell and a 2x 123 cell stack that is partially depleted?

As long as you never exceeded the 6v input voltage for the light, you shouldn't have any concerns by putting in a lower voltage power source.

I've been running my U2 on a li-ion cell for some time now. It works just fine with it (some have reported a decrease in the max brightness, that may be true, but I don't notice or care about it). 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?

 

[Kiessling]

If you installed a single li-ion cell @ ~4.2v max it cannot damage the light. Otherwise, how does the circuitry know the difference between a Li-ion cell and a 2x 123 cell stack that is partially depleted?

One hypothesis as already explained would be the circuit has to draw more current becasue of th elow voltage. With a depleted stack of 2x123 they just won't deliver and th elilght gets dimmer, you loose the high levels and change your batteries.
With a Li-Ion ... is delivers. A lot of current, more than 2x123 deliver when new. And there might be parts in the circuit that can't take so much current and subsequently die.
Which could explain why a Li-Ion kills the light. It however just a guess as no-one knows the circuit.


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

 

[kromeke]

One hypothesis as already explained would be the circuit has to draw more current becasue of th elow voltage. With a depleted stack of 2x123 they just won't deliver and th elilght gets dimmer, you loose the high levels and change your batteries.

Bad hypothesis IMHO. There were a number of assumptions made and little data to back it up. If that is the case, then they are depending on the batteries to be a "choke point" and that would be a bad circuit design if you ask me.

I agree that one should run Li-ions at your own risk, but I will always take issue with a warranty that specifies a specific brand of a standardized cell.

 

[Kiessling]

A lot of lights are built around the specific capabilities of the batteries they use. Take a SF 3x123 incan light, P91 for example. You drive it with 3x123, a 9V system, and you're fine. You hook it up with a power supply and feed it 9V you insta-flash the bulb. This is because the set-up takes into account that the voltage of the required batteries sags under load in order to function properly.

Could be the same here. The system runs fine on 6V and continues to do so when the batteries die as they can't deliver more current while their voltage sags, and thus you loose your high levels and are otherwise fine.
Feed the light some batteries that have a different behaviour when dying ... and the light has a problem.
I think this is not a bad system, it is a tool that requires specific batteries. Like almost any other tool

Feed 22V to a 110V electronic gadget and it will fry. Bad design?

But anyway ... pure speculation. And I agree that until now, the U2 was able to run on Li-Ion provided you had a battery tube that allowed for it.
Now the U2A ... maybe a different story?

bernie

 

[kromeke]

Feed 22V to a 110V electronic gadget and it will fry. Bad design?

For sake of argument, I'll assume you meant 220v to a 110v gadget. Otherwise I don't think it will fry.

And if that is what you meant to say, I'll say it again, bad analogy. Volts is volts and current is current. They are not interchangeable.

I'm not trying to be argumentative, but substituting a Li-ion cell for a 2x 123 stack is less voltage, not more. Yes, it may be able to provide a higher current at a given voltage than a partially depleted 2x 123 stack, but the voltage is always less, not more.

My question stands, is it the original U2 with the lux V, which seems to have a proven track record with regards to Li-ion cells, vs. a U2a, which, as far as I've seen, there has been little data on using a li-ion cell in it?

Does anyone here run a U2a with li-ions? Several people have said that a U2 with the Lux V running a li-ion cell puts out less light at the highest level than running it with primaries. This tells me that the buck-boost circuit in the original U2 might current limit itself, such that it won't damage it. The U2a is a different animal.

 

[Kiessling]

The original U2 has a boost circuit. Not buck/boost.


Simple question, just for the sake of it: is more current than it was designed for a reason for a circuit to fail? Is it plausible that a circuit draws more current to compensate for a lower voltage? Is it possible that a Li-Ion cell can deliver that current whereas the cells the circuit was designed for can't? Is it thus possibe that using a lower voltage cell can actually damage a circuit?
Hypothetically speaking, of course.

bernie

 

[kromeke]

The original U2 has a boost circuit. Not buck/boost.

Ok, I'll accept that at face value.

On to your hypothetical questions:

Simple question, just for the sake of it: is more current than it was designed for a reason for a circuit to fail? Is it plausible that a circuit draws more current to compensate for a lower voltage? Is it possible that a Li-Ion cell can deliver that current whereas the cells the circuit was designed for can't? Is it thus possibe that using a lower voltage cell can actually damage a circuit?
Hypothetically speaking, of course.

Yes,
Yes,
Maybe, I'm not that intimate with li-ion cell behavior.
I think that is the big question, I don't know, but if said circuit can indeed draw more current than it was designed for, then I suppose it might be able to.

Also, to change tangent a little, here is a little data on running a li-ion cell in the U2a:

http://www.candlepowerforums.com/vb/showthread.php?p=2666918

But that is just from some forum on the internet, take all this with a grain of salt. Seriously. I haven't met any of you guys, I don't know if most of what is said here is true. I do know that I have had no problems running a li-ion cell in my U2, which is unmodified with the original battery tube. It has what appears to be a luxeon V in it. Anything else is just a guess. Some of you guys take big risks with expensive toys. Edit: I mean tools, yes, tools.