Will I explode myself?

[Grinder]

Another question from the front lines of PC turd polishing:

I've cut yet another crusty barrel-type 3.6V battery out of a '486
board. It was too crudoded to get specifics on, but it's the ones that
look like:

http://www.dsmiller.com/Images/B-430PC2.GIF

With a couple of D-cells, I've confirmed that 3.0-3.2 volts is enough to
sustain the CMOS settings across a shutdown. That setup is unwieldy and
not up for donation, so I'd like to use some heat shrink tubing to put a
couple of AAs together and solder on some leads. (There's already a
pair of leads coming off the board with a pin header jumper on the end.)

Will I explode something if I try to solder leads onto an AA battery?

What can I do to make the solder stick?

Is there a better way to do what I'm attempting without having to spend
another dime? (I already have the crap I'm proposing to use.)

To preempt a possible answer to that last question: Yes, I know I should
drive by a construction dumpster late at night and "solve" the problem
with one heave, but I already have my soldering iron hot.

 

[Paul]

Another question from the front lines of PC turd polishing:

I've cut yet another crusty barrel-type 3.6V battery out of a '486
board. It was too crudoded to get specifics on, but it's the ones that
look like:

http://www.dsmiller.com/Images/B-430PC2.GIF

With a couple of D-cells, I've confirmed that 3.0-3.2 volts is enough to
sustain the CMOS settings across a shutdown. That setup is unwieldy and
not up for donation, so I'd like to use some heat shrink tubing to put a
couple of AAs together and solder on some leads. (There's already a
pair of leads coming off the board with a pin header jumper on the end.)

Will I explode something if I try to solder leads onto an AA battery?

What can I do to make the solder stick?

Is there a better way to do what I'm attempting without having to spend
another dime? (I already have the crap I'm proposing to use.)

To preempt a possible answer to that last question: Yes, I know I should
drive by a construction dumpster late at night and "solve" the problem
with one heave, but I already have my soldering iron hot.

Is that a NiCAD ? That implies a constant charging current, when the computer
is running. What will happen to an alkaline under those conditions (application
of constant charging current) ? I've be a bit cautious about the application.
I was going to suggest adding a diode to the battery output, so the current
can only flow one way (so the battery never gets charged), but then that will
drop your terminal voltage to the CMOS circuit. (Maybe you could go to 4.5V
with three cells, and use two 0.7V drop forward biased diodes ?)

I've soldered to batteries. I have four C cells sitting in the kitchen, that
are connected together with stranded wire and solder. But the cells are
cheapies, and have steel contact plates on each end, making soldering
pretty easy. I've had other batteries, where all I managed, was a bunch of
cold solder joints. YMMV. No explosions yet.

Paul

 

[Grinder]

Is that a NiCAD ?

It appears the the picture I linked is a NiCD, but I just picked the
picture because it showed the proper shape.

That implies a constant charging current, when the computer
is running. What will happen to an alkaline under those
conditions (application of constant charging current) ?
I've be a bit cautious about the application. I was going
to suggest adding a diode to the battery output, so the
current can only flow one way (so the battery never gets
charged), but then that will drop your terminal voltage
to the CMOS circuit. (Maybe you could go to 4.5V with three
cells, and use two 0.7V drop forward biased diodes ?)

[snip]

The original cell was very crusty. The plastic wrapping it was almost
completely destroyed, and I did not dissect it to look for identifying
marks. The board, where the battery was soldered, is marked "DS12887."
That, apparently, is a RTC with an inbuilt Lithium power
source--clearly not what was actually on the board.

I can't find a specific reference to what battery was on the board, but
other boards from the same manufacturer in the same period used external
Lithium batteries.

 

[John McGaw]

Another question from the front lines of PC turd polishing:

I've cut yet another crusty barrel-type 3.6V battery out of a '486
board. It was too crudoded to get specifics on, but it's the ones that
look like:

http://www.dsmiller.com/Images/B-430PC2.GIF

With a couple of D-cells, I've confirmed that 3.0-3.2 volts is enough to
sustain the CMOS settings across a shutdown. That setup is unwieldy and
not up for donation, so I'd like to use some heat shrink tubing to put a
couple of AAs together and solder on some leads. (There's already a
pair of leads coming off the board with a pin header jumper on the end.)

Will I explode something if I try to solder leads onto an AA battery?

What can I do to make the solder stick?

Is there a better way to do what I'm attempting without having to spend
another dime? (I already have the crap I'm proposing to use.)

To preempt a possible answer to that last question: Yes, I know I should
drive by a construction dumpster late at night and "solve" the problem
with one heave, but I already have my soldering iron hot.

Probably won't explode yourself but the results may not be very
satisfactory. The materials used in dry cell manufacture just don't solder
very well -- that is the reason that makers of battery packs spot weld the
jumpers. You'd be way ahead if you just went out and bought an
old-fashioned battery holder instead.

http://www.radioshack.com/product/index.jsp?productId=2102736

John McGaw
http://johnmcgaw.com

 

[John McGaw]

Is that a NiCAD ?

It appears the the picture I linked is a NiCD, but I just picked the
picture because it showed the proper shape.

That implies a constant charging current, when the computer
is running. What will happen to an alkaline under those conditions
(application of constant charging current) ?
I've be a bit cautious about the application. I was going to suggest
adding a diode to the battery output, so the
current can only flow one way (so the battery never gets charged), but
then that will drop your terminal voltage to the CMOS circuit. (Maybe
you could go to 4.5V with three cells, and use two 0.7V drop forward
biased diodes ?)

[snip]

The original cell was very crusty. The plastic wrapping it was almost
completely destroyed, and I did not dissect it to look for identifying
marks. The board, where the battery was soldered, is marked "DS12887."
That, apparently, is a RTC with an inbuilt Lithium power
source--clearly not what was actually on the board.

I can't find a specific reference to what battery was on the board, but
other boards from the same manufacturer in the same period used external
Lithium batteries.

What you have there is a Dallas Semiconductor clock with built-in battery.
A real antique -- I have a 486 MB in the basement which uses two DS parts.

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2680



John McGaw
http://johnmcgaw.com

 

[terryc]

Will I explode something if I try to solder leads onto an AA battery?

nope, that is what I did, but I suggest liberal use of fine sandpaper for
metal on all ends before you start and a good capacity soldering iron.
Getting the solder to stickto the ends of the battery is hard first time.

Is there a better way to do what I'm attempting without having to spend
another dime? (I already have the crap I'm proposing to use.)

Go for it.
BTDT.

worst problem was sticking the batteries on the side of the power supply
and keeping them there.

If you can do it, make the leads 12-24" and just tape the bateries in
place on the bottom of the case(tower?).