# When is 9 volts "not" 9 volts (in a P91 module)?

#### luxlover

##### Banned
When is 9 volts \"not\" 9 volts (in a P91 module)?

I received my SureFire P91 lamp bezel on Saturday. Using my E1e body, two Dspeck 123 battery extensions, and a Z57 tailcap, "that sucka is bright." That sucka also says 9V (for 9 volts) on the side. Well, something was wrong with that lamp. When my good buddy with a regulated power supplied applied "exactly" 9 volts to the module's leads to see how much current the lamp would consume, the lamp worked.......and then it didn't work.......... At no time did the voltage exceed 9.00 volts. After seeing that the lamp did not work with my three battery light, I took a peek at the lamp's filament with a magnifying glass. By golly, the filament had a break on one side, where the coiled section meets the vertical section. The lamp was deader than dead, and neither of us know why. This is why I chose the title for this post to be "When is 9 volts "not" 9 volts in a P91 module?"

Even though when a P91 lamp is energized by three 123 batteries, the batteries have a voltage drop to less than 9 volts (about 7.80 volts) due to the huge current draw, there was no reason that the regulated 9 volts should have burned out the lamp. The lamp is rated to handle 9 volts, plus a little more as a means of protection against overvoltage spikes. Are SF's lamps conservatively rated at 9 volts, but are in reality not able to handle that level?

So what gives with this burned out 9 volt lamp? Should I call "Ghostbusters?"

#### McGizmo

##### Flashaholic
Re: When is 9 volts \"not\" 9 volts (in a P91 module

luxlover,
I did the same thing a couple years ago and realized that SF pushes the edge with their lamps based on the real voltage, with drop factored in, from the CR123 cells. Yup, truth in advertising here! The LA should say for 3xCR123 use on the side and no mention of voltage. Some jerk will say that the batteries say 3 volt so 3x 3 Volt = 9 Volt so why not call the dang lamp 9 Volt! No body is going to hook it up to a *real* 9Volt supply! /ubbthreads/images/graemlins/grin.gif

As I understand it, we are all entitled to blow one lamp in this fashion. Should you do a second one in this manner, I hear the hot wire police will come after you!! /ubbthreads/images/graemlins/icon15.gif ( 's why I stick to LED's! /ubbthreads/images/graemlins/grinser2.gif )

#### TORCH_BOY

##### Flashlight Enthusiast
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Drop in voltage across the bulb is quite common with
that arrangement

#### KevinL

##### Flashlight Enthusiast
Re: When is 9 volts \"not\" 9 volts (in a P91 module

luxlover, the 9V P91 is actually a 6+V lamp. Lithium 123s sag very heavily under the 2.3A load, and drop voltage really fast, thus keeping them within spec. A constant-current 9V source would be heavily overdriving the lamp.

Brock's page: http://www.uwgb.edu/nevermab/flash.htm

McGizmo: In which case Ginseng would be a wanted convict? /ubbthreads/images/graemlins/grin.gif

I blew half a dozen 'free' PR bulbs for fun, too... /ubbthreads/images/graemlins/grin.gif I fed a 4.8V bulb 2 x 18650 lithium ion once for kicks and damn the sucker was bright... for 20 minutes. /ubbthreads/images/graemlins/evilgrin07.gif

#### luxlover

##### Banned
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Don,
That is so nice. However, how is a poor soul like myself with an "ultra inquisitive mind", to know that a marking of 9V really means 7.8V? I feel no guilt whatsoever, even though as you said "Nobody is going to hook it up to a *real* 9 volt supply! Let SF play the game fairly, and print "for 3xCR123 use", as you have so eloquently suggested. That would surely scare people like me away from using a regulated power supply. Nobody would know where to set the voltage or how high to push it, would they!

<font color="blue">Regardless of what they wrote on the lamp or what I did, a customer service rep at SF has already agreed to send me a replacement P91 module, after hearing my "heartwrenching" story. In this case, SF did indeed demonstrate it's "world class customer service."</font>

I like your line about sticking to LEDs. As you very well know by now, I am a devout LED man too. But with a free "lamp conversion kit" at the party, and a few mothballed body components capable of hosting 200 lumens of incandescent light, I couldn't resist buying the module. Furthermore, I had to "push the envelope" by replacing the P60 with the highest output lamp that could fit my existing E-series parts. I am sure that you "understand" my motive. After all, I am the inimitable luxlover (lover of "lux"). As Walter Brennan used to say on the TV show "The Real McCoys", "No brag.....just fact!"

TORCH_BOY,
I am aware of what you have stated. But when a bloke like myself sees an inscription on the side of a lamp module stating 9V, it can only mean 9V, no ifs, ands, or buts! SF and all of us, are definitely suffering from a total lack of communication. I know better now, but will the next guy with a very "lean mean regulated power supply machine" know this? I think not!

KevinL,
Where have you been? I did measure a 2.30 amp current draw across the battery, and I did measure a 7.80 volt potential across the batteries when the P91 was still alive. Otherwise, ditto to you what I wrote to TORCH_BOY above.

Be good all, and be careful with your lamp modules. Danger lurks behind every corner! It's a jungle out there......

#### KevinL

##### Flashlight Enthusiast
Re: When is 9 volts \"not\" 9 volts (in a P91 module

You're a tweaker, same as most of us.... SF lamps were never meant to be run on a constant-current supply so for all INTENDED intents and purposes, it's "9V". You know better, but Joe Q. Average is going to ask "uhh, but me flashlight sez 7V and I don't think I can use 3 batteries" /ubbthreads/images/graemlins/tongue.gif

#### brightnorm

##### Flashaholic
Re: When is 9 volts \"not\" 9 volts (in a P91 module)?

[ QUOTE ]
luxlover said:
...Are SF's lamps conservatively rated at 9 volts, but are in reality not able to handle that level?...

[/ QUOTE ]

Surefire conservatively rates output (lumens), though considering industry-brghtness exaggeration "conservative" may simply mean "accurate".

Brightnorm

#### Zelandeth

##### Flashlight Enthusiast
Re: When is 9 volts \"not\" 9 volts (in a P91 module)?

Definitely right here, and I've fried incans more than once in the same manner.

Worth noting though, that the supply in question is a constant voltage supply I think, rather than constant current as is seems to have ended up getting quoted at. Just before that ends up confusing someone.

#### MrMom

##### Enlightened
Re: When is 9 volts \"not\" 9 volts (in a P91 module)?

Lux I was worried when I saw you with that incan head at the party. I just kept thinking: "He's an LED man..."

#### luxlover

##### Banned
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Kevin,
A tweaker, and proud of it! By the way, Eddie Chong, one of Paul Kim's support people at SureFire, told me that a P91's lamp is made to handle 9 volts, and should not have fried upon the application of 9 volts from a regulated power supply.

From what I understand about Ohm's Law, when a voltage is applied to a resistor (a lamp's filament), the filament determines how much current it needs by dividing it's resistance into it's voltage. The resistor extracts from the power supply, the current that it needs to energize. Bottom line is that pushing 9 volts into a P91 lamp module should not have fried the filament, unless the lamp was defective and was not able to handle any voltage higher than that provided by three 123 batteries under load, i.e. about 7.80 volts. My three very fresh 123 batteries each measured 3.25 volts before first use, and these added up to 9.75 volts which was applied to the lamp......even if just for a few seconds until the batteries experienced their drop in voltage when current draw increased as a result of the filament and gas inside the lamp heating up. My feeling is that the lamp was a bum lamp........end of case!

#### luxlover

##### Banned
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Zelandeth,
Thank you for picking up the innocent error, that an incandescent lamp doesn't get a constant current supply as do Luxeon emitters. I believe that the important parameter to be kept constant with incandescent lamps is voltage. Too much of it and the filament burns apart. Too little of it and the gases inside the lamp do not ignite and no light is produced.

Mr. Mom,
You were right to worry about how I was going to "handle" my incandescent bezel gift. As you have read above, I got into trouble by just applying my scientific education to the lamp module. I will have to bring this matter to the attention of somebody at SureFire, for the safety of many of us equally "inquisitive" incandescent lamp users.

#### McGizmo

##### Flashaholic
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Luxlover,
You may be right on the lamp being a bum lamp. /ubbthreads/images/graemlins/icon3.gif OTOH, I bet with a regulated power supply you could find a lot of "bum" lamps that might have survived well in the environment of which they were intended for.

Just how many people outside of our "silliness" will buy an expensive SF LA with intents of using it in other than a SF light? /ubbthreads/images/graemlins/thinking.gif

On the LED side, I can give you a LED lamp that is designed to run on 12V. And I mean 12V! You can put it in an automotive system that is 12V (look right on the battery!) and the 14.6 volts from the alternator will do the same thing to this LED lamp that you did to the SF LA. /ubbthreads/images/graemlins/nana.gif

#### KevinL

##### Flashlight Enthusiast
Re: When is 9 volts \"not\" 9 volts (in a P91 module

[ QUOTE ]
luxlover said:
Kevin,
A tweaker, and proud of it! By the way, Eddie Chong, one of Paul Kim's support people at SureFire, told me that a P91's lamp is made to handle 9 volts, and should not have fried upon the application of 9 volts from a regulated power supply.

My feeling is that the lamp was a bum lamp........end of case!

[/ QUOTE ]

Wow, that is indeed something. I'll take it from them since they know the product better than my idle speculation without instruments.

Bum lamps do happen, I've had two. Good to see that they took care of you, too.

#### luxlover

##### Banned
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Yes, Kevin. SureFire does have "world class customer service." I have always been properly accommodated by them in the past. But it needs some fine tuning in the area needed to give it the title of "world class communicator!"

I am sure that had we applied a regulated 7.8 volts to the lamp, it would have done well and lasted as long as SF estimates.....about 20 hours continuous. There is no harm in duplicating conditions "inside a light", "outside a light." This is the way of science!

#### luxlover

##### Banned
Re: When is 9 volts \"not\" 9 volts (in a P91 module

You will need a better analogy to make your point, Don......
For those of us who know how a car's charging system operates, it would indeed be foolish to connect a 12 volt LED to that system. But if the charging system were to be a flat 12 volts, even though the LED was not "intended" to be used across a battery, it should not burn out. The same goes for a lamp module that has "9V" imprinted on it's side, that is not necessarily "intended" to be used with a regulated 9 volt power supply pushing "exactly" 9 volts. Had the illustrious manufacturer of this incandescent lamp intended on having us use it "only" in their lights, the "9V" rating would not have been imprinted on the side of the module, and "to be used only in lights powered by 3 123 batteries" would have been there instead. The inclusion of the "9V" gives us license to apply any voltage we wish to the lamp, from any source, "as long as that doesn't exceed 9 volts." How else can "9V" be interpreted? I remind you that SF's Eddie Chong states that "9V" = 9 volts!

Now to your statement about not using a lamp in the manner intended by the manufacturer......
The guy who burned out my P91 lamp has had a regulated power supply pump up a Luxeon I for over a year, hanging from his ceiling 24 hours a day, 7 days a week. You may ask why he has done this? He wants to determine how the Luxeon's output level will deteriorate over time, how the voltage will change, and approximately how many hours the emitter will give of usable light. He first applied 3.42 volts at 350mA, regulating the current at this figure for the duration of the test, to replicate the conditions seen by an emitter in a light with current regulation (downboy, badboy, atta-boy). After nine months, the voltage dropped to 2.75 volts with no degradation in output. Note that he has a luxmeter to be used for measuring "relative" change. So far, the voltage drop shows an increase in efficiency. He will continue the "experiment" outside the venue intended for the emitter by the manufacturer, until either he dies.....or the lamp dies. Can you tell me how else such a test can be done with an emitter, when Luxeon posts lifespan figures for it's emitters "in the thousands of hours", especially since those hours are for continuous use and not intermittent use?

Hope to see you at Shot Show next year, at which time we may continue this discussion on the semantics of electric ratings given my manufacturers, "tete a tete."
/ubbthreads/images/graemlins/nana.gif back at you!

Be good......

#### luxlover

##### Banned
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Why has this important thread ended so soon. I was just getting warmed up!

#### Size15's

##### Flashaholic
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Do you sometimes find that you've answered your own question?

#### McGizmo

##### Flashaholic
Re: When is 9 volts \"not\" 9 volts (in a P91 module

Luxlover,
Your pursuit for "truth in print" is one that can not be denied and I wish you well on your journey. I decided a long time ago that aside from some words purportedly carved in stone on a mountain top, all printed words were the result of man and often the words or numbers themselves required consideration of context and served as a guide or generalization more than being statement of fact or "truth". Heck the only statement that I am comfortable as proclaiming as true, regardless, is the following statement:

True

I take the label on the SF LA as a guide for proper selection of LA for host based on stated voltage and relative to voltage stated on cells. I learned after burning up a P61 on a power supply putting out 6 VDC that I could not take the stated voltage literally. I could have raised a stink about it but somehow found other more pressing matters; I think it was looking for orphaned socks.

While you are on your quest, perhaps you can contact the manufacturers of the CR123 cells and suggest that they remove 3V from the cells as well. Have you yet measured a CR123 that is actually 3V?!?!? And why call it 3V when it drops under load, in actual use, sometimes by a half volt?!?!? If the 3V statement on the CR123 cells is taken as fact, then the 9V stated on the suspect LA is in the same realm of "truth".

To answer your question in the subject line:

9 volts is "not" 9 volts when 3 x 3 volts is not 9 volts.

Edited out due to inappropriate attempt at poor humor

#### jtr1962

##### Flashaholic
Re: When is 9 volts \"not\" 9 volts (in a P91 module

OK, I'll "out" myself as the one who blew luxlover's lamp but despite what udaman may think because of my general dislike of incandescents (actually not a dislike so much as a feeling that they are obsolete for many applications) there was no malice intended. Anyway, to answer a few questions the power supply was one I designed and built myself. It has both voltage and current limiting. Under no load the output will equal the voltage limit. It will continue to do so unless the output current reaches the current limit. I get feedback right from the output terminals so as to compensate for any internal voltage drop inside the supply. Anyway, the current limit was set well beyond what the lamp would take at 9 volts so we essentially had a constant 9 volts at the power supply terminals (and a little less where we connected test leads to the lamp due to voltage drop). At no time was it possible for the voltage to exceed 9V. The output is heavily filtered with a few thousand µF in electrolytics so any transients will be very small in amplitude. The lamp blew because it couldn't take 9V sustained as it was already technically heavily overdriven at maybe 7.8V.

As for truth in advertising here, cells may say 3V or 1.25V or 1.5V and not be exactly that but provided they are speced consistently this isn't a problem. Most cells are speced under no or light load. In the case of a lithium cell it will indeed give 3V over most of life under light light. A NiMH will give an average of 1.25V over it's life, and so forth. Most lamps I've seen are stamped with a rated voltage and current which is usually dead on balls accurate. You can rate the same lamp at different voltages depending upon the lifetime you want but the fact remains that so long as you keep within the specs the lamp won't blow out right away unless it's defective. A household 100W lamp will give 750 hours at 120 VAC but it is also possible to sell it as a 180 VAC bulb with a rated life of a few hours (and a much higher rated output). Both would be acceptable. SF's lamp has an inaccurate voltage rating and no current rating stamped on it. This was the crux of the problem.

Now that I've said my 2 cents I think we can all put this matter to rest. I certainly won't lose sleep over it since I don't own any SF lights, incandescent or otherwise.

#### luxlover

##### Banned
Re: When is 9 volts \"not\" 9 volts (in a P91 module

[ QUOTE ]
Luxlover,
With a proper diet, plenty of rest and perhaps outside counceling, you can get over this problem! I have faith!

[/ QUOTE ]

Look at the comment above. This is a general post for all to see, especially the administrator of this forum. The last comment by McGizmo was something I did not expect of him, nor do I like it. It is the job of the administrator of this forum to apply the rules of CPF to all members, even Don McLeish. Read and reread this comment, and let me see how you will handle it, since it represents "baiting", part of Rule 4 of the CPF Forum's Rules and Guidelines. When I did the same to McGizmo and Size15S about two months ago, the administrator "Bart" gave me a stern/threatening warning, at which time I retracted my comment. He was right to do so. I expect no less of the administrator of this forum, directed at Don.

Whomever has read Don's comment should have given him a slap on the hand, in the same manner as it was given to me "publicly." I expect it and demand it, "immediately." There will be no double set of rules between regular CPF members, and sponsors or supporters like Don who are in the inner circle in CPF. One set of rules for all members, period!

Don,
You stepped over the line of decency. You have disappointed me, because your comment has nothing to do with reality. Only our discussion about the semantics of SF's ratings has anything to do with reality. Retract your insulting statement, so that the next time I look at my most wonderful, meaningful, and caring thread, I won't see it there staring me in the face. By the way, your habit of placing the "nana" graemlin after every one of your nasty comments, "is meaningless." It doesn't exonerate you from the guilt of insulting people on CPF for their opinions.

Come to think of it, why the hypocrisy when you also fried a SF lamp using the power supply method? Your use of the benign task of "finding orphaned socks" instead of making a stink for your destroyed lamp, was no more polite than the comment above. You were trying to make the point that the pursuit of useless socks is of greater importance to you than dealing with SF over their rating and your action of destroying one of their lamps. Lastly, look at how many people in this thread have believed that an SF lamp module rating was accurate, and acted as I did......as we did. There is something to be said about this, isn't there? Too many of us have been misinformed too many times, in too many situations. It is getting old!

Luxlover, out!