Flashlights!

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Re: Flashlights!

Postposted on Sun Aug 15, 2010 12:30 pm

Every time someone mentions powerful flashlights, I am reminded of this:

http://www.candlepowerforums.com/vb/sho ... hp?t=92396

Granted, not really the handheld size but still... now THAT would be something to mount on my beige volvo!
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Re: Flashlights!

Postposted on Sun Aug 15, 2010 5:54 pm

That's the flashlight G-d uses when he loses his keys.
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Re: Flashlights!

Postposted on Sun Aug 15, 2010 6:12 pm

That is one heck of a light. Now, if that is a circa 1985 tank search light, what sort of stuff are they using now? :o

Also:
nexxcat wrote:My keychain has a 4sevens Quark Mini attached to it. http://www.4sevens.com/index.php?cPath=297_355

I picked it after looking at candlepower forum's cheap flashlight reviews. The anodizing does come off pretty easily, and the split-ring is very weak, but it's a solid flashlight that will throw plenty of light. I lit up a tall tree at my friend's house at night, much to the amazement of my spectators :)
Just how weak is the split-ring? I am looking at the Quark Tactical AA (for the features, not to be "tacticool") and would like to know how well built it is. I don't really care too much about the anondizing, just whether the ring will snap in my pocket when connected to my leatherman + keys and how good the seals are.
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Re: Flashlights!

Postposted on Sun Aug 15, 2010 7:13 pm

bryanl wrote:The tuning of LED color is an ongoing effort. Most has been towards lights that provide a good white balance. The requirement for a color that would reflect off the back of an animal's eye could have some interesting market implications. I don't know but perhaps different animals have different retina sensitivities so an LED manufacturer could customize a lamp for a particular type of hunting?

Typically eye reflections are yellowish-orange, probably a combined effect of blood vessels in the eye and the low-pass filter effect caused by the lens and the vitreous humor. Incandescent bulbs tend to put out a lot of light from infrared to the higher end of yellow, hence the advantage.

LEDs for these color frequencies exist but there's not an obvious advantage to building a flashlight in that output range, especially not for the proposed application -- an excess of visible light simply warns the target that you're coming while reducing your own optical sensitivity.
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Re: Flashlights!

Postposted on Tue Aug 17, 2010 9:41 pm

Actually, the first time I ever realized that insects and arachnids had eye-reflection was when I shined my LED headlight into the forest. It looked like there was a thousand diamonds scattered about. Upon closer inspection, it was hundreds of spiders hanging there. I spent my childhood wandering forests at night with traditional incandescent flashlights, and never noticed this before.

Now that I'm looking further into flashlights, I'm pretty amazed at how many high-end flashlight makers there are. I don't know a single person who has such hardcore, military-style flashlights, yet there seems to be dozens of companies making them: SureFire, EagleTac, Fenix, Wolf Eyes... the list goes on, and on, and on... The flashlights are all so similar, in specs as well as price, that it's hard to tell them apart.

I'm curious about something that maybe some of the electronic guru or chemistry guru types here could answer. Flashlights that have regulated output -- where the beam stays at a particular brightness for a period of time, then drops off suddenly -- almost always run on CR123 or lithium batteries of some variety. Alkaline- or NiMH-powered flashlights always have a steady decrease in brightness over the course of the battery. Why is it that flashlight makers only regulate lithium batteries? I hypothesize that there might be something with the internal chemistry of the batteries, but I've been searching for days and haven't come up with anything. I'm looking for an in-depth answer that's probably above my head.
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Re: Flashlights!

Postposted on Tue Aug 17, 2010 10:04 pm

FireGryphon wrote:I'm curious about something that maybe some of the electronic guru or chemistry guru types here could answer. Flashlights that have regulated output -- where the beam stays at a particular brightness for a period of time, then drops off suddenly -- almost always run on CR123 or lithium batteries of some variety. Alkaline- or NiMH-powered flashlights always have a steady decrease in brightness over the course of the battery. Why is it that flashlight makers only regulate lithium batteries? I hypothesize that there might be something with the internal chemistry of the batteries, but I've been searching for days and haven't come up with anything. I'm looking for an in-depth answer that's probably above my head.

The "regulation" has nothing to do with the flashlight maker and resides solely in the battery tech. Lithium batteries deliver their rated voltage until they die. When they reach their end, voltage dies quickly. Alkaline and NiMH batteries sag their voltage from turn-on.

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Re: Flashlights!

Postposted on Wed Aug 18, 2010 12:52 am

Captain Ned wrote:The "regulation" has nothing to do with the flashlight maker and resides solely in the battery tech. Lithium batteries deliver their rated voltage until they die. When they reach their end, voltage dies quickly. Alkaline and NiMH batteries sag their voltage from turn-on.

Small addendum to that: If you disassemble a decent-quality LED flashlight that uses cells adding to more than 3V, you will probably find a surface-mount transistor regulator that actively holds the white LED's forward voltage to its 3V tolerable range. These will correspondingly tend to output a constant light for most of the battery life, followed by a comparatively rapid falloff, even if using conventional alkalkines.

I have a 3-AA LED-native Maglight constructed this way and I love it, because it can hold a near-constant light output until the batteries are super-duper dead. My other LED-native Mags are 2-AA and tend to fall off a bit quicker.
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Re: Flashlights!

Postposted on Wed Aug 18, 2010 1:11 am

Yeah, I was going to reply to that too, and got distracted.

FWIW NiMH cells have a pretty even voltage during discharge as well, though they don't do as well as lithium under extreme loads.

Some AA/AAA powered lights (generally the more expensive ones) have regulators. Less expensive ones may have a simple current-limit resistor, or (in the case of cheap junk ones) simply rely on the internal resistance of the battery to limit the current to a safe amount.

As an aside, compact single AA (or AAA) LED flashlights must contain some sort of boost regulator by definition, since the forward voltage of white LEDs is higher than the voltage supplied by the battery...
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Re: Flashlights!

Postposted on Wed Aug 18, 2010 5:24 am

Which flashlights have alkaline batteries totaling more than 3V that have a steady output, then, besides the MagLite (XL100, I assume)? I like AA batteries since they are common and cheap, and I wouldn't mind a flashlight slightly larger and heavier that uses and extra couple of alkalines.
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Re: Flashlights!

Postposted on Wed Aug 18, 2010 7:35 am

I know my Fenix E01 has regulation that gets constant output - on an ordinary alkaline, about 10 hours of constant output, and then another 6 hours of declining output. But, that's 1AAA. (I get about 16 hours of constant output, and another 10 of declining output, from an Energizer e^2 lithium, on that light.)
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Re: Flashlights!

Postposted on Wed Aug 18, 2010 11:04 am

FireGryphon wrote:Which flashlights have alkaline batteries totaling more than 3V that have a steady output, then, besides the MagLite (XL100, I assume)? I like AA batteries since they are common and cheap, and I wouldn't mind a flashlight slightly larger and heavier that uses and extra couple of alkalines.

Why the more than 3V requirement?

The Ace Hardware one I linked a while back uses a pair of AAs. I haven't personally verified that the light output remains steady as the batteries discharge, but it pretty much has to have some sort of regulation circuitry in it since 3V isn't enough.
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Re: Flashlights!

Postposted on Wed Aug 18, 2010 3:43 pm

just brew it! wrote:The Ace Hardware one I linked a while back uses a pair of AAs. I haven't personally verified that the light output remains steady as the batteries discharge, but it pretty much has to have some sort of regulation circuitry in it since 3V isn't enough.

3V is plenty if you want to build it cheap. Any blue or white LED constructed with Vf=3.0-3.4V will be above its knee point for the practical life of the batteries.
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Re: Flashlights!

Postposted on Wed Aug 18, 2010 6:43 pm

FWIW here's the 3-cell light I've got:

http://www.amazon.com/dp/B000PWDDXO/ref ... _pe_vfe_t3
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Re: Flashlights!

Postposted on Thu Aug 19, 2010 10:46 am

re: "Any blue or white LED constructed with Vf=3.0-3.4V will be above its knee point for the practical life of the batteries."

As I understand it, an LED is current driven. You need a voltage above the 'knee point' but you also have to limit the current. That means you can't just connect an LED to a battery but have to have either a resistor in series or some other current limiting device.

The low cost resistor in series model is going to need sufficient voltage headroom from battery voltage to deal with the resistor's voltage drop while keeping the current at maximum voltage within the LED's ratings. These sorts will suffer current, hence brightness, drops when the battery voltage drops. These 3 cell flashlights, especially the cheaper ones, seem to fall into this category.

The current limiting devices are usually IC's that are specifically tailored for LED illumination and provide boost voltage controllers as well. These are usually what you need for single cell flashlights, especially for white light and higher power levels. I'd think the multiple selected brightness levels would also indicate a light using this sort of device.

Which LED is being used seems to be an interesting factor, too. I note some of the real cheap ones use very many LED's. I wonder how they are wired to balance the currents. Then there's the household light bulb replacements starting to show up in stores - those have to have some interesting circuits, too.

I remember when flashlights had to be illumination in only short bursts because otherwise the 2 D cells would leave you in the dark in short order. Nowadays, a single cell LED light can run off much less battery for much longer periods. So much so that spelunkers and others can use them. Less worry about needing to carry spare light bulbs or battery leakage, too. The cost is also low enough you can have a spare flashlight or two for backup without much hassle as well.
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Re: Flashlights!

Postposted on Thu Aug 19, 2010 11:50 am

Actually, if the voltage is at or below the LED's Vf, the resistance needed to limit the current is exceedingly small, and on cheaper lights it may be achieved (as someone else noted) by relying solely on the battery internal resistance.

That said, a resistor is a passive current-limiting device. It is possible to use a transistor as an active current limiter. In simplest form this means pulling the transistor's collector current through a very small reference resistor, and then using the voltage drop across the resistor as negative feedback into the transistor base.
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Re: Flashlights!

Postposted on Mon Aug 23, 2010 7:05 pm

My old led flashlight has been failing lately so i decided i would hop into the newer generation and bought a Fenix P3D Q5. It probably would have been a better idea to go with one that had a lower power mode, but i don't think i'll ever actually look back and regret the decision.

Also about the constant thing. I'm not sure what the amperage is that these lights pull, but maybe increasing the current on AA alkalines isn't an option for most higher powered lights?
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Re: Flashlights!

Postposted on Tue Aug 24, 2010 2:50 am

Heiwashin wrote:Also about the constant thing. I'm not sure what the amperage is that these lights pull, but maybe increasing the current on AA alkalines isn't an option for most higher powered lights?

Anything is possible with a sufficient series/parallel combination of cells, but the light may become infeasibly large and/or have a ridiculously short battery life.
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Re: Flashlights!

Postposted on Mon Jan 31, 2011 10:32 pm

The idea took some time to simmer on the back burner, but I finally ordered a Surefire G3D. It has three light levels, very nice run times, and should be very durable. Besides price my biggest concern was the odd batteries (CR123A? Huh?) but I'm willing to try 'em. I thought about the Stratum but I opted for the G3D in favor of longer run times.

My Tektite 4-LED flashlight lasted for over a decade before I just noticed that the batteries had been in there so long they started to leak! It's a shame; the flashlight has been using the same batteries for probably five or more years now, and the only reason it doesn't light is because the batteries leaked and caked the inside with dried acid. Hopefully the lithiums that the Surefire takes will fare better with time.
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Re: Flashlights!

Postposted on Mon Jan 31, 2011 10:59 pm

FireGryphon wrote:Besides price my biggest concern was the odd batteries (CR123A? Huh?) but I'm willing to try 'em.

They're not really that odd; they used to be very common in photography applications until everything moved to proprietary rechargeable lithium ion batteries. They're fairly popular for LED flashlights because they have twice the voltage of standard alkaline batteries and high energy density. Downside is that they're kind of pricey.
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Re: Flashlights!

Postposted on Tue Feb 01, 2011 1:06 am

just brew it! wrote:They're not really that odd; they used to be very common in photography applications until everything moved to proprietary rechargeable lithium ion batteries. They're fairly popular for LED flashlights because they have twice the voltage of standard alkaline batteries and high energy density. Downside is that they're kind of pricey.


Yeah, they're about 3x the price of AAs. Energy capacity is actually quite similar - a CR123 has 1500 mAh @ 3V = 4.5 Wh. An AA has 2700 mAh @ 1.5V = 4.05 Wh. So the CR123 only stores 10% more energy. The benefit as you say is the higher voltage - a CR123 torch can be half the length of an AA design to provide the same input voltage to an LED torch. Given the choice between the two, I generally go for the AA, but some designs are only available in CR123.

PS My old 3 color LED flashlight had the same problem as Firegryphon's - the batteries leaked acid all over the insides. It's still usable but the contacts have corroded and it seems to have degraded the output. Looking at one of these as a replacement: http://www.coleman.com/coleman/colemanc ... 110&brand=

If someone can suggest a better alternative, I'm all ears. I like having the red light for nightvision, but don't like having to fiddle with screw on filters.
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Re: Flashlights!

Postposted on Tue Feb 01, 2011 6:17 am

The Exponent 2 has decent specs, but Amazon's users have this to say:

Amazon's user review wrote:While this flashlight produces a good amount of light, I simply don't believe that this light is producing 165 lumens. The beam is wider and more diffused than some of the tactical flashlights I've played with... The light seems durable and water resistant. However, I noticed that there is a piece of lint inside the lens and I can't open up the flashlight without damaging the finish -- this would never happen with a Surefire or Fenix light (which you can get at the same price).


From that description -- whatever it's worth -- the light doesn't sound like it's worth $80, even though it wraps white and red LEDs into a nice combo.

At peril of going OT a bit, I read an article that said that the color of light has little or no impact on night vision, rather it's the intensity of the light. Basically, if the lumen level is low enough any light is sufficient to preserve night vision, and white light is best since you can see colors and better judge your surroundings. That goes against common knowledge, but the article went into great detail about the physical nature of our eyes and made a pretty good case. Not sure what to make of its conclusions.
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Re: Flashlights!

Postposted on Tue Feb 01, 2011 6:42 am

FireGryphon wrote:At peril of going OT a bit, I read an article that said that the color of light has little or no impact on night vision, rather it's the intensity of the light. Basically, if the lumen level is low enough any light is sufficient to preserve night vision, and white light is best since you can see colors and better judge your surroundings. That goes against common knowledge, but the article went into great detail about the physical nature of our eyes and made a pretty good case. Not sure what to make of its conclusions.


Bright light depletes our nightvision because the rod receptors in our eyes store little rhodopsin and are quickly depleted. A bright light (of any color) will diminish our nightvision faster than dim light. Red light preserves nightvision because our rods are not sensitive to the long wavelength, when we illuminate our surroundings with red light, we're actually using our cones (our daylight receptors) to see.

http://en.wikipedia.org/wiki/Night_visi ... ght_vision
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Re: Flashlights!

Postposted on Tue Feb 01, 2011 6:47 am

In a bit of a hurry, but check out this interesting page: http://stlplaces.com/night_vision_red_myth/
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Re: Flashlights!

Postposted on Tue Feb 01, 2011 11:03 am

And then there's always Energizer e2s. About 3000 mAh, 1.5 V nominal. CR123A capacity in a AA. (The big advantage to CR123As over alkaline AAs is the discharge rate, however - lithium batteries can handle higher discharge rates without voltage sag. The e2s are also lithium, though. Myself, I run a AAA e2 in my Fenix E01.)
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Re: Flashlights!

Postposted on Tue Feb 01, 2011 12:10 pm

I could never spend money on surefire. For 110$ I'm getting my 800 lumen tk35, which if its as reliable as other fenix lights will be wonderful. The only thing is that surefires must be far more reliable but they better be able to take a bullet for their premium.
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Re: Flashlights!

Postposted on Mon Feb 07, 2011 1:43 pm

My tk35 came in today, maybe at night i'll take a shot or two to try to represent how well it lights, but lets say that using it on it's highest mode inside with the lights off will leave you unable to see as if you had been outside when you turn the lights on. It feels very solid, perfect size for a backpack light. I'll still be keeping my pd30 on my keychain.

On the cr123A note, i buy energizer lithiums from a seller on amazon. Can get a pack of 10 for around 20$'s. I decided it'd be fun to stop in at radio shack and price theirs since i just assumed about any local store would be over priced but never verified it.They sell a pack of 2 radio shack branded batteries for 20$'s. Seriously guys? 10 dollars a battery? When i started laughing the sales guy smirked too, i assume he understood my disbelief.
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Re: Flashlights!

Postposted on Mon Feb 07, 2011 2:31 pm

If you're willing to buy them in lots of 100 or more, you can get them even cheaper than that from distributors like Digi-Key.
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Re: Flashlights!

Postposted on Mon Feb 07, 2011 8:19 pm

I know they're supposed to be good for 10ish years but i'm still hesitant about planning to buy for that long ahead. If i find a flashlight crew willing to split one i'd go in though.
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Re: Flashlights!

Postposted on Fri Feb 11, 2011 12:14 am

just brew it! wrote:I've been pretty happy with this one. I'm sure it's just someone else's light with an Ace Hardware logo stenciled on the side. Runs on two AAs (I use a couple of low-self-discharge NiMHs).


I bought something very similar the other day. It's amazingly bright compared to the old bulb torches i'm used to. :D
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Re: Flashlights!

Postposted on Sat Feb 12, 2011 1:56 am

Damn, I read the topic title as "Fleshlights!"
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