I have 14 eaches, squeeze LED lights. Two flat thin cells, I
think are CR-2016. Is it cheaper to replace the batteries,
or should I pitch them and buy new?

The LED can be removed relatively easily. Can that run on
three D cells for a super long lasting night light? I
remember something about a current limiter resistor.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..

On 12/18/2010 6:17 PM, Stormin Mormon wrote:
I have 14 eaches, squeeze LED lights. Two flat thin cells, I
think are CR-2016. Is it cheaper to replace the batteries,
or should I pitch them and buy new?

The LED can be removed relatively easily. Can that run on
three D cells for a super long lasting night light? I
remember something about a current limiter resistor.

I've only got one, on my key chain, that I think I'm gonna cannibalize
when battery burns out. The switch contacts are just two wires with
casings that can slip and I've had to adjust as light either goes on too
easy, like in my pocket, or requires too much squeezing.

Mine are prerty much just the clamshell, two cells, and the
two wires. I havn't tried changing batteries. Maybe I'll
bend the wires too much while I have them apart, and they
won't work right. I did have a quick look at batteries on
Ebay, and the entire lights are pretty close in price.

When yours uses up the battery, I saw earlier that the LED
present nearly zero rsistance after they warm up. The button
cells run "wide open throttle" which is low enough amp
supply that it doesn't burn out the LED. I think typical LED
runs 20 mA. At 4.5 volts, and .020 amps,

E = IR or R = E / I
R = 4.5 / .020 = 225 ohms.

Of course, my math may be out of whack some where.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Frank" wrote in message
...

I've only got one, on my key chain, that I think I'm gonna
cannibalize
when battery burns out. The switch contacts are just two
wires with
casings that can slip and I've had to adjust as light either
goes on too
easy, like in my pocket, or requires too much squeezing.

Frank wrote in
:

On 12/18/2010 6:17 PM, Stormin Mormon wrote:
I have 14 eaches, squeeze LED lights. Two flat thin cells, I
think are CR-2016. Is it cheaper to replace the batteries,
or should I pitch them and buy new?

The LED can be removed relatively easily. Can that run on
three D cells for a super long lasting night light? I
remember something about a current limiter resistor.

the CR-2016's are 3V lithium cells,two for a total of 6v.
you only have 4.5V with the 3 D cells.
a white LED runs on about 3.5V,around 20ma.
no more than 25ma max continuous.


I've only got one, on my key chain, that I think I'm gonna cannibalize
when battery burns out. The switch contacts are just two wires with
casings that can slip and I've had to adjust as light either goes on too
easy, like in my pocket, or requires too much squeezing.




--
Jim Yanik
jyanik
at
localnet
dot com

In , Jim Yanik wrote:
Frank wrote in
:

On 12/18/2010 6:17 PM, Stormin Mormon wrote:
I have 14 eaches, squeeze LED lights. Two flat thin cells, I
think are CR-2016. Is it cheaper to replace the batteries,
or should I pitch them and buy new?

The LED can be removed relatively easily. Can that run on
three D cells for a super long lasting night light? I
remember something about a current limiter resistor.

the CR-2016's are 3V lithium cells,two for a total of 6v.
you only have 4.5V with the 3 D cells.
a white LED runs on about 3.5V,around 20ma.
no more than 25ma max continuous.

Most "low power" white LEDs are rated 30 mA max. continuous. I have
seen them surviving 40 mA, but with probably a significant compromise in
life expectancy.

Meanwhile, the life expectancy of these at 20 mA is usually less than
50,000 hours, sometimes closer to 10,000 hours.
--
- Don Klipstein )

Because of the small size of the thin cells, they can run
"wide open" without doing too much damage.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Jim Yanik" wrote in message
4...

the CR-2016's are 3V lithium cells,two for a total of 6v.
you only have 4.5V with the 3 D cells.
a white LED runs on about 3.5V,around 20ma.
no more than 25ma max continuous.

--
Jim Yanik
jyanik
at
localnet
dot com

Andy comments:

I'l like to present something here that is of general interest.

The LED flashlights that one gets for free from Harbor Freight
have 9 LEDs , in paralled, run by three AAA cells with no
current limiting resistor.
The current draw is in the neighborhood of 160 ma.....

I fabricated a piece that can be inserted into the back
of the flashlight without modification of the original unit.

It is a piece of double sided G-10 board, approx the size
of a dime, with the copper trimmed slighly away from the edges to
keep copper on each side from shorting to the case of the light.
A small notch is cut, and a 100 ohm resistor is inserted so that
the current will flow from one side, thru the resistor, to the
other side.

The "coin" is then inserted into the BACK of the flashlight
and the back cap screwed back on...

This effectively inserts a 100 ohm resistor between the negative
terminal of the battery and the negative terminal of the flashlite
--- a current limiting resistor....

The resultant current is 16 mils (approx) to the nine LED
array, total.....

The light output decreases, but still puts out enough to
read by, or find one's way in the dark. My guess is about
1/3 or the original, by eyeball only......

The batteries are no longer working into a short circuit, but
only supplying about 1/10 of the original current, and should last at
least
10 times a long as before....

If one wants to restore full brightness, one has only to remove
the "coin" insert....

I've done this with about a dozen LED flashlights that I keep
in the car, house, pocket, garage, etc.... It works well..

Give it a try. If you have a more simply, or more innovative way
to accomplish this, I'd be most interested in learning about it...

Andy in Eureka, Texas P.E.

On Dec 19, 8:12*am, Andy wrote:
Andy comments:

* I'l like to present something here that is of general interest.

The LED flashlights that one gets for free from Harbor Freight
have 9 LEDs , in paralled, run by three AAA cells with no
current limiting resistor.
* The current draw is in the neighborhood of 160 ma.....

* I fabricated a piece that can be inserted into the back
of the flashlight without modification of the original unit.

* It is a *piece of double sided G-10 board, approx the size
of a dime, with the copper trimmed slighly away from the edges to
keep *copper on each side from shorting to the case of the light.
A small notch is cut, and a 100 ohm resistor is inserted so that
the current will flow from one side, thru the resistor, to the
other side.

* *The "coin" is then inserted into the BACK of the flashlight
and the *back cap screwed back on...

* *This effectively inserts a 100 ohm resistor between the negative
terminal of the battery and the negative terminal of the flashlite
--- a current limiting resistor....

* * The resultant current is 16 mils (approx) to the nine LED
array, total.....

* * The light output decreases, but still puts out enough to
read by, or find one's way in the dark. My guess is about
1/3 or the original, by eyeball only......

* * The batteries are no longer working into a short circuit, but
only supplying about 1/10 of the original current, and should last at
least
10 times a *long as before....

* *If one wants to restore full brightness, one has only to remove
the "coin" insert....

* *I've done this with about a dozen LED flashlights that I keep
in the car, house, pocket, garage, etc.... It works well..

* *Give it a try. If you have a more simply, or more innovative way
to accomplish this, *I'd be most interested in learning about it...

* * * * * * * * Andy in Eureka, *Texas * * *P.E.

Great idea! I'd use a 25 - 50 ohm resistor to get more brightness and
still have longer life than the original. My experience always seems
to be the battery self-destructs after a couple of years before I use
the light enough to drain the battery from actual use.

In article
,
Andy wrote:

The LED flashlights that one gets for free from Harbor Freight
have 9 LEDs , in paralled, run by three AAA cells with no
current limiting resistor.

Thanks for the new vocabulary word:

Paralled: Two or more LEDs wired in parallel.

On 12/19/2010 8:12 AM Smitty Two spake thus:

In article
,
Andy wrote:

The LED flashlights that one gets for free from Harbor Freight
have 9 LEDs , in paralled, run by three AAA cells with no
current limiting resistor.

Thanks for the new vocabulary word:

Paralled: Two or more LEDs wired in parallel.

Shouldn't that be "paralLED"?


--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.

On Dec 19, 6:22 pm, David Nebenzahl wrote:


Thanks for the new vocabulary word:

Paralled: Two or more LEDs wired in parallel.

Shouldn't that be "paralLED"?


Andy comments:

Apparently, my pun went over like a LED balloon.....

..... anyway, the idea works..... I am not trying to misLED anyone....

Andy in Eureka

PS The value of the resistor is just a trade-off. Nothing magic
about 100 ohms... It was the value that gave me the amount
of light I needed.....