Led Flashlights

This improved version of battery was the self contained dry cells. These self contained dry cells were more beneficial than the led acid batteries, because they were smaller and were much more reliable. During the same period, a new kind of led flashlights was developed. These led flashlights were named as the dynamos. Dynamos are the led flashlights that make use of the energy, which is created by the movement of the led flashlights. Dynamos became popular and much more practical at that period of time, because the storage density of batteries was not too much. Dynamos proved to be much more practicable during that period of time. Not every part of the world had laws regarding the compulsion of having led flashlights. In UK the led flashlights group actually went against the law of led flashlights having the rear lights. This was because; they thought that this law will reduce the significance of the motorist’s obligation to stop when they would see a bicycle within a clear distance. http://www.eclipseledcompany.com /
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What the f*ck are you rambling on about?
You do know that many of those "dynamo" flash lights that were supposedly powered by movement, actually had tiny batteries in them to run the lights... Because the LED was so efficient a little button cell could be hidden in the head of the flashlight and would run it for many hours.
The "shaker" and tube of copper wire was all for show.
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snipped-for-privacy@rochester.rr.com wrote the following:

I think samaden was PUI. Posting Under the Influence. He asserts that flashlights had lead acid batteries. Lead acid batteries are used in automobiles. (did you have to check the water level occasionally?)
--

Bill
In Hamptonburgh, NY
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Coolest flashlight I ever had was a "moon" or "space" flashlight, which I bought new in the early 70s. It was supposed to be a spinoff from space technology. It was about the size of a 4oz can of mushrooms, maybe an inch longer. It was made of chromed plastic, had a twist on/off switch, incandescent bulb, and was completely sealed. There was no way to replace anything. You jes turned it on and waited for it to come on. When new, that was about 5-10 secs. Later, it became as long as a minute. Bottom line, owned and used that little flashlight for almost 15 yrs before it finally launched its last lumen.
I used it hundreds of times and it was my always-there, always-works, emergency flashlight and it did its job perfectly. At one point it sat in a drawer, unused, for almost 5 yrs. Then I had a power outage and coldn't find my main flashlight. I remembered my lil' space light, dug it out, turned it on, and after about a minute, it came on, almost bright as new. If I could find another one, I'd buy it in a heartbeat. I've never seen another like it, since.
nb
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wrote:

I bought a "shaker" LED flashlight in a dollar store for $3 thinking it was a great deal,but it turned out it had two 3V lithium cells,a CR2032 and a CR2012,the induction coil wires were not even connected,the "magnet" was a piece of unmagnetized soft iron,and there was no storage capacitor on the little circuit board.
did you know there are cylindrical sealed lead acid batteries? I had a battery pack that comprised 6 of them to make 12V,they were F-sized cells. You can also buy Coleman camping lanterns at WalMart that have sealed lead acid battery packs.
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Jim Yanik
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wrote:

No, he said they had led acid batteries.

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I suppose you've never heard of SLACs (Sealed Lead Acid Cells), or "Gell Cells". Not all lead-acid batteries need the water level "checked".
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snip
Go smoke your spam somewhere else.
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Andy comments:
I have a number of those small LED flashlights that I got free from Harbor Freight for visiting the store. They use three AAA cells in series driving nine LEDs in parallel, with no current limiting. When on, the drain from the AAA cells is about 160 ma.
As a retired engineer, I made up a little thingy about the size of a dime which can be inserted in the back between the battery terminal and the little spring. This inserts a 100 ohm resistor in series with the AAA cells and drops the current drawn to about 16 ma.
Since the current draw is 1/10 of an unmodified flashlight, the AAA cells will last a bit longer than 10 times as long......
The light output is reduced, but not drastically so. All the LEDs still light and the light output is more than enough to see your way in a darkened room or read a book by.....
I have modified all my little LED flashlights this way, and all work about the same.
My "thingy" is a piece of double sided G-10 with a small 1/4 , 100 ohm resistor put in a slot which connects one side to the other. The shape is like a dime, so it will easily fit right in behind the AAA cells in the back...
Just wanted to pass this along in case someone here would like to try it...
Andy in Eureka, Texas
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I have bought at least 9 led flashlights. Only a couple were reliable. I always have to bang on them. Those colored ones were the worst. The best which I use most often, and also has a fairly warm light, I bought at Target, River Rock, and of course, unavailable. I bought some from Deals Extreme and none were reliable.
Greg
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Very, very interesting. To understand how you built it, I'd sure like to see some photos, maybe even on a "MACRO" setting.
Does seem to me that a dime is pretty thick for inserting behind one of those AAA batteries.]
And, what's a G-10 (double sided)?
You say "right in behind the AAA cells" ie plural -- if they're in series, all you need do is put it *somewhere* in the circuit, ie behind any *one* of the cells? Or am I missing some basic concept of what you've done?
Question: how did you measure the amps pulled? That is, where and how did you break the circuit so you could insert the ammeter (part of a vom)? At least in my 3-AAA led lights and headlamps, it's a pretty tight fit.
Obviously you have some neat technique that I'd like to learn!
Thanks,
David
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David Combs wrote:

I think G10 is a phenolic/fiberglass board with copper plating on both sides. http://www.electricalinsulationmaterial.com/g10-fr4.html
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wrote:

If you turn it backwards, can you use your flashlight as a firestarter? ;-)
Steve
Heart surgery pending? www.heartsurgerysurvivalguide.com Heart Surgery Survival Guide
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snipped-for-privacy@panix.com (David Combs) wrote in wrote:

with new cells?

100 ohms seems like a lot,the math doesn't add up. .16a x 100R = 16 volts drop.
maybe 10 ohms,or 1 ohm?

no,it goes between the internal 3 cell battery holder and the spring that contacts the holder.

you can get .031" double-sided plated circuit board(plated on both sides...),the good stuff is made of G-10 epoxy glass. it's thinner than a dime. .062 (1/16") is about the same as a dime. I buy mine at Skycraft Surplus,Orlando.
A SMD chip resistor would be about right. (SMD is surface mount device;tiny.)

I think he put it in behind the battery holder and the end cap. that's how I would do it. then it can't short the LED board.

DMM's (digital multimeter) are more accurate. VOMs are the old analog meters,like a Simpson 260 or Triplett.

you take the flashlight's end cap off,and put your probe tips between the center contact of the battery holder and the alum. case. I think the 200ma range of a DMM has too much resistance and alters the current flow,distorting the measurement. Use the 20A range,or if your DMM has a 2000ma range,use that. the higher the meter's current range,the lower it's internal resistance.
something you HAVE to consider for current measurements; the meter's internal resistance.
for volts,the DMMs input R is usually 10 MegR,but the cheap HF DMMs are only 1 MegR. A VOM is rated ohms per volt,most VOMs are 20Kohms/volt,so a 10 volt range is 200K ohms load on the circuit under test,and it goes up as the VOM range is increased. A DMM is constant load resistance over all the volts ranges.
But current meter resistance changes with the range selected. Ohm's Law R=E/I,so for a 200ma range,the DMM has 1 ohm resistance;the basic DMM volts range being 200mv full scale.

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Jim Yanik
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