Warning for anyone soldering lithium cells .....
Lithium cells are an entertaining entity. If you can buy them as such, buy
them with the solder tags welded on by the supplier, then solder onto the
solder tags. If you have to solder onto the cell directly, do it quickly
(as stated below).
And my advice, however you do it, is WEAR GOGGLES. These things can, and
do, sometimes explode under extreme circumstances (temperature, shorting,
etc.). It is rare, but can happen, and the resulting mess can blind you if
it gets in your eyes. Another piece of advice is ensure your soldering iron
tip isn't grounded (some specialist ones are, to avoid static discharge to
circuits). Positive end of lithium cell, grounded soldering iron tip, nice
short circuit if not careful !!
Just my 2 cents worth (or whatever that is in GBP !) Some people may want
to disagree with me and provide chemical reasons why this is not the case,
but hey - better safe than sorry and I wouldn't want anyone to get hurt.
Regards,
Jon
-----Original Message-----
From: owner-olympus@xxxxxxxxxxxxxxx [mailto:owner-olympus@xxxxxxxxxxxxxxx]
On Behalf Of Joe Gwinn
Sent: 17 December 2001 02:00
To: olympus@xxxxxxxxxxxxxxx
Subject: [OM] Replacing lithium cells; Soldering delicate circuitry
At 9:42 PM +0000 12/16/01, olympus-digest wrote:
>Date: Sun, 16 Dec 2001 11:46:30 EST
>From: ClassicVW@xxxxxxx
>Subject: [OM] Help!- My Quick Flash AFL question
>
>Ok,
>So I now have the bottom battery panel off, and pulled out the two 3V
Lithium
>batteries that are wired in there. I am assuming these power both the flash
>and the camera, and were not intended to be replaced by the user. The code
on
>the side says 83-07, so i also assume they were in there since 1983. The
>designation is "BR- 2/3 A 3V". Can I just buy two 3V lithiums and solder
them
>in place of these if I keep the heat of the soldering gun low?
It ought to work, if the lithium batteries will fit physically, without
stray electrical contacts being made. The batteries used are probably a
standard size (like 2/3 of an "A" cell?). Try looking at the Eveready
website <http://www.energizer.com> under the Technical Information button.
(It seems to require Internet Explorer. When I use Netscape, the site
crashes my computer.)
However, it's a common myth that one uses low heat for delicate things. You
should instead use a very hot iron, and get the job done as quickly as
possible.
The extreme case is soldering magnet wire to terminal pins moulded into
nylon coil forms -- if you don't use an 800-degree iron, the bobbin will
melt as you slowly heat the terminal pin. Been there, done that.
I use an ancient Weller TCP-1 temperature-controlled soldering iron. One
sets the temperature by using the correct tip. No electronics are involved.
I bought one after working at RCA in the mid 1960s, and seeing them used on
the production line. This iron is now the basic unit in Weller's TCP line.
600-degree tips are used for eutectic (37-63) solder
700-degree tips are used for ordinary (40-60) solder
800-degree tips are used for magnet wire (where one burns the insulating
varnish off and solders all at once). I use 800-degree tips to solder
delicate things. This hot tip gets the solder terminal up to temperature as
fast as possible, reducing the amount of collateral heating, which is the
key issue.
A soldering *gun* may be hard on semiconductor eletronics, as the tip is
heated by passing a very large current through the tip, and this can induce
large currents in unexpected places. Also, an iron solders more quickly
because the tip is already at temperature, and so its stored heat is
instantly available.
Joe
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