john hamilton wrote:
I'm replacing a small button battery (CR 2032) with two AAA batteries, I'm
intending to leave the old discharged button battery in its place and solder
the leads from the AAA batteries directly on to the button battery.

Is the heat that I would need to apply to the button battery with the
soldering iron to solder to it, likely to make the battery prone to
'leakage' in the future? Or perhaps cause it to go bang at the time of
soldering? Thanks for advice.


don't do it.
make a dummy battery. A disk of double sided ecb material will work.
solder to the copper, shim for thickness.
Don't have a disk?
use a nickel and a dime with insulation between.
Depending on the socket, you may have to build up the
diameter a little with solder.

On Tue, 24 Aug 2010 11:21:33 -0700, mike wrote:
john hamilton wrote:
I'm replacing a small button battery (CR 2032) with two AAA batteries, I'm
intending to leave the old discharged button battery in its place and solder
the leads from the AAA batteries directly on to the button battery.

Is the heat that I would need to apply to the button battery with the
soldering iron to solder to it, likely to make the battery prone to
'leakage' in the future? Or perhaps cause it to go bang at the time of
soldering? Thanks for advice.


don't do it.
make a dummy battery. A disk of double sided ecb material will work.
solder to the copper, shim for thickness.
Don't have a disk?
use a nickel and a dime with insulation between.
Depending on the socket, you may have to build up the
diameter a little with solder.

**** it. Just buy a few batteries.

I've never soldered to a button cell, but had no trouble with flashlight batteries.

[snip]

I've seen it multiple times with little keychain lights powered by dual
(very thin) 2016 lithium cells (button cells are numbered according to
diameter and width: a 2016 is 20mm in diameter and 16mm thick.

The dimensions above describe a much thicker cell. Perhaps the thickness
of a 2016 is supposed to be 1.6mm.

The
keychain lights have no current limiting resistor in place (they don't
even have spring switches, just the LED leads cut short to act as one
with the batteries inserted between them).

I've had one like that. It wasn't easy to change the battery (2 2016
cells). You have to remove 6 little screws (that stick to the screwdriver
and fall off in inconvenient places) and try to keep the remainder from
falling apart.

Press on the case and
current flows from the leads through the battery and back.

That "switch" never worked right. It was impossible to keep the light on
steadily for more than a couple of seconds.

There isn't a
simpler circuit in the world. Wire an equivalent number of AA or AAA
cells in place instead of the two thin button batteries and the LED
burns out in very short order.

I accidentally connected one on 12V once. There was a loud POP and half
the LED disappeared.

[snip]

--
Mark Lloyd
http://notstupid.us

"The power of accurate observation is called cynicism by those who have
not got it." - George Bernard Shaw

On 27 Aug 2010 17:46:54 GMT, Mark Lloyd
wrote:

[snip]

I've seen it multiple times with little keychain lights powered by dual
(very thin) 2016 lithium cells (button cells are numbered according to
diameter and width: a 2016 is 20mm in diameter and 16mm thick.

The dimensions above describe a much thicker cell. Perhaps the thickness
of a 2016 is supposed to be 1.6mm.

The
keychain lights have no current limiting resistor in place (they don't
even have spring switches, just the LED leads cut short to act as one
with the batteries inserted between them).

I've had one like that. It wasn't easy to change the battery (2 2016
cells). You have to remove 6 little screws (that stick to the screwdriver
and fall off in inconvenient places) and try to keep the remainder from
falling apart.

Press on the case and
current flows from the leads through the battery and back.

That "switch" never worked right. It was impossible to keep the light on
steadily for more than a couple of seconds.

There isn't a
simpler circuit in the world. Wire an equivalent number of AA or AAA
cells in place instead of the two thin button batteries and the LED
burns out in very short order.

I accidentally connected one on 12V once. There was a loud POP and half
the LED disappeared.

[snip]
I guess I don't waste my money on $1.00 keychain lights - and the
Laser pointers I've repowered have never had a problem.

"Mark Lloyd" wrote in message
.com...
[snip]

I've seen it multiple times with little keychain lights powered by dual
(very thin) 2016 lithium cells (button cells are numbered according to
diameter and width: a 2016 is 20mm in diameter and 16mm thick.

The dimensions above describe a much thicker cell. Perhaps the thickness
of a 2016 is supposed to be 1.6mm.

Perhaps indeed. (-: That would not be much of a button cell at 20/16mm.
It is, of course, as you point out, 1.6mm.

The
keychain lights have no current limiting resistor in place (they don't
even have spring switches, just the LED leads cut short to act as one
with the batteries inserted between them).

I've had one like that. It wasn't easy to change the battery (2 2016
cells). You have to remove 6 little screws (that stick to the screwdriver
and fall off in inconvenient places) and try to keep the remainder from
falling apart.

I began shopping for more when I realized that the frustration of dealing
with rebuilding them was greater than a $2 replacement with better features.
The newer solar ones are a great improvement and should outlast the old
button powered ones because they can recover from "sit on" accidentally
run-downs in my pocket. I am a "flashlight freak" because I know so many
people who've done themselves serious injury stumbling around in the dark.
I hang them off all suitcases, bags, keychains and even as the weight to the
pull-chain light in the basement (with a strip of glow tape).

Press on the case and
current flows from the leads through the battery and back.

That "switch" never worked right. It was impossible to keep the light on
steadily for more than a couple of seconds.

Unless you were sitting on it balled up your pocket. Then it worked
ine. )-: I prefer the ones that have slide switches in addition to the
pushbutton ones or some way to keep it on continuously. I've had them
clamped in my teeth when I needed both hands free, and managed to keep the
momentary pushbutton closed, but that incident (car electrical system total
failure on the side of the road) made me realize how important a "continuous
run" setting is on these things.

There isn't a
simpler circuit in the world. Wire an equivalent number of AA or AAA
cells in place instead of the two thin button batteries and the LED
burns out in very short order.

I accidentally connected one on 12V once. There was a loud POP and half
the LED disappeared.

I can imagine. Just like there are car "hot-rodders" and computer
overclockers, there's a small band of LED overdrivers determine to stay just
inside the explosion range.

[snip]

--
Mark Lloyd
http://notstupid.us

"The power of accurate observation is called cynicism by those who have
not got it." - George Bernard Shaw

Reminds me of a quote I heard today (paraphrase) "We know the details of the
lives of great historical figures thanks to the overactive imaginations of
so many scholars."

--
Bobby G.

An experienced and educated in soldering person will first "sand" off the
coating and solder to the material underneath using a proper heat sink. If
that's a problem and sometimes it can be he switched to jewelers or one of
the many other types of solder available.



In .com,
Mark Lloyd typed:
[snip]

I've seen it multiple times with little keychain lights
powered by dual (very thin) 2016 lithium cells (button
cells are numbered according to diameter and width: a
2016 is 20mm in diameter and 16mm thick.

The dimensions above describe a much thicker cell. Perhaps
the thickness of a 2016 is supposed to be 1.6mm.

The
keychain lights have no current limiting resistor in place
(they don't even have spring switches, just the LED leads
cut short to act as one with the batteries inserted
between them).

I've had one like that. It wasn't easy to change the
battery (2 2016 cells). You have to remove 6 little screws
(that stick to the screwdriver and fall off in inconvenient
places) and try to keep the remainder from falling apart.

Press on the case and
current flows from the leads through the battery and back.

That "switch" never worked right. It was impossible to keep
the light on steadily for more than a couple of seconds.

There isn't a
simpler circuit in the world. Wire an equivalent number
of AA or AAA cells in place instead of the two thin button
batteries and the LED burns out in very short order.

I accidentally connected one on 12V once. There was a loud
POP and half the LED disappeared.

[snip]

wrote in message
...
On 27 Aug 2010 17:46:54 GMT, Mark Lloyd
wrote:

[snip]

There isn't a
simpler circuit in the world. Wire an equivalent number of AA or AAA
cells in place instead of the two thin button batteries and the LED
burns out in very short order.

I accidentally connected one on 12V once. There was a loud POP and half
the LED disappeared.

[snip]
I guess I don't waste my money on $1.00 keychain lights - and the
Laser pointers I've repowered have never had a problem.

I like to root around to see what's good and what's not. F'rinstance, I
bought two different handheld LED projection clocks that display the time
projected on a dark ceiling. (Great for late-night time checks without
having to put on my glasses - a little penlight unit project digits almost a
foot wide. Both models were way under $5, but the "cleaner" looking one was
substantially dimmer than the other. I wouldn't think there would be such a
performance difference, but there was.

The handcrank rechargeables LED flashlights turned out to be pretty much
worthless - they seemed to work at first, and definitely responded to
cranking, but testing them out a year later shows them to be almost dead.
No amount of cranking puts out a decent amount of light. But I keep
trying - maybe someone will make one that actually works.

I'll admit I haven't repowered many laser pointers. What types have you
repowered? Button to AA or what? My impression of some of the new ones is
that they pull some of the same tricks - using higher than spec voltage but
interrupting it 100 times a second or so to keep it from burning out
immediately. I've been buying a lot of the high visibility green laser
pointers (the kind that can illuminate low level clouds and get you put in
jail if you shine it on the wrong people). The QC on these items is quite
variable, and once again, the switches are the weakest link. They are now
below $10 each, including shipping, from many Ebayers.

I've come to prefer the smaller 3 way units (flashlight, UV light
(counterfeit bill detector) and laser pointer just because they are smaller
and multifunctional. I also have a fondness for 5 way pens, (UV, laser
pointer, gooseneck LED flashlight, plastic tipped stylus and pen) although
their bad button design means I buy button cells by the hundreds to repower
then when I have put them away lit without realizing it. Still, a great aid
in many situations - the little gooseneck LED lamp is like having a third
hand to hold a flashlight.

--
Bobby G.