On Sat, 22 Dec 2012 06:14:53 -0800, "William Sommerwerck"
wrote:
I have a 200/260W Weller solder gun and when I gave it some thought,
when someone spot welds a tab onto the battery, it creates a momentary
hot spot on the battery. The Weller gun can't to worse than a spot weld
as long as the time is short and proper preparation is made.
Oh, yes it can. A spot weld takes a fraction of a second, and the heat appears
over a small area.
A bit more than a fraction of second. See video at:
http://www.youtube.com/watch?v=G7LKhhyokbQ
starting at 0:50. I would guess(tm) about 1/2 second for the spot
weld. I would also guess(tm) that the heat affected zone on the
battery is much larger with the high wattage Weller because of the
longer dwell time and larger thermal contact area. When I was
soldering batteries, the cell was noticably warm after soldering. When
doing the same with a CD welder, it was stone cold.
By golly, I had no trouble at all and the results turned out great!
I test my battery packs with a West Mountain Radio CBA-II.
http://www.westmountainradio.com/product_info.php?products_id=cba4
If there's a problem, it will be obvious on the graphs.
I hope so. I've seen connections of this sort fail * with the solder blob
simply falling off the battery.
Not if you sandpaper the base metal. When I solder to a battery, the
solder will wet to the edge of the sandpaper zone, but not into the
non-sandpapered area. That implies that there's some manner of
coating on the battery case that should be removed with an abrasive
before soldering.
* as do spot welds, of course
The real problems are in high current applications, where the weld
turns into a fuse. Power tools are a good example. I did a lousy job
of replacing NiMH cells in a Makita 18V driver. After about 4 hrs of
use, the pack went to open. An autopsy showed that my welds had fused
open. I went to 4 spots instead of 2 spots per terminal, and it was
fine.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558