"Point welding"?

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Hi All,

How do you call the technique that attaches those extremely thin
(0.01") tabs to the steel casing of rechargeable battery cells so that
they can be soldered to wires or connectors?

Looking closely at the welded tabs, they have very small, point-like
signs of having being fused.

Also... Any ideas for achieving this in a DIY fashion?

"Point welding"?
Hi All,

How do you call the technique that attaches those extremely thin
(0.01") tabs to the steel casing of rechargeable battery cells so that
they can be soldered to wires or connectors?

Looking closely at the welded tabs, they have very small, point-like
signs of having being fused.

Also... Any ideas for achieving this in a DIY fashion?

Re: "Point welding"?
On Tue, 12 May 2009 12:35:34 -0300, Bruno wrote:

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Spot welding -- it's just a very small spot.

The spot welder that I had the opportunity to work with used copper
electrodes and put a controlled current through the electrodes.  Because
the underlying steel had a higher resistance than the copper, and because
the electrodes tapered down, the current would heat the steel far more
than the copper and weld everything nicely together (at least if
everything was nice and clean before hand).

Dunno about the particulars for spot welding battery straps.  It may well
depend on melting the nickel plating, you'd almost certainly have to make
sure that the strap material was compatible.

Hopefully someone who actually knows will be motivated by all my
erroneous and/or vague statements to come and correct them...

--
www.wescottdesign.com

Re: "Point welding"?
Thanks Tim,

As obvious as it sounds *now*, I tried and tried but coulf not come up
with SPOT welding!

...Off to Google again, do some more searching - now that I know what
to look for.

Thanks again!

wrote:

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Re: "Point welding"?

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Try: "resistance spot welding battery pack" as a search term. Bring
lots of cash when you go shopping...

http://sunstoneengineering.com/site/pages/sales/#dpcap_2007

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DJ

Re: "Point welding"?
On Tue, 12 May 2009 15:38:18 -0600, IdaSpode wrote:

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-- snip --

I saw those prices, too.  It does make one want to DIY, at least if it
can be done economically.

--
www.wescottdesign.com

Re: "Point welding"?
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Battery tab welding has been discussed on SEJW in the past and can be
found archived thru google groups: http://tinyurl.com/prpef6

One discussion in 2002  (http://tinyurl.com/ok8ul9 ) led to this
posting in the metalworking.com website dropbox:
http://www.metalworking.com/dropbox/_2002_retired_files/BatteryTabWelder.pd =
f
The author (MikeR) used a microwave transformer and timing circuit
(using a GAL20V8 PAL chip), but didn=92t include a schematic.

A more recent discussion on SEJW ( http://tinyurl.com/pxwybb ) led to
this link: http://www.5bears.com/welder.htm
It uses an octal timer, solid state relay and modified transformer.

A DIY capacitance discharge (CD) welder is described here:
http://www.philpem.me.uk/elec/welder /
Schematic:
http://www.philpem.me.uk/elec/welder/images/schematic.png
Discussion: http://www.rcgroups.com/forums/showthread.php?t=3D763308

Other DIY microwave transformer spot welder videos:

http://www.youtube.com/watch?v=3D9spgDiU3_nw&NR=3D1


http://www.youtube.com/watch?v=3DZ7M9_YEqF6o


This one is a particularly nice build showing controls for pulse width
and voltage (but no schematic):

http://www.youtube.com/watch?v=3DyabesdeGKJo


There is also a relatively new Yahoo discussion group
=93batterytabwelding=94, but it has gotten only a few posts.

Commercially available Sunstone CD welder video:

http://www.youtube.com/watch?v=3DmWhWix72jJo


Re: "Point welding"?
I have never had a problem *soldering* leads to cells.



Re: "Point welding"?
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Soldering directly to many cells (lithium comes to mind) is a recipe
for a rather spectacular destruction of the cell, involving lots of
smoke. DAMHIKT. That's why they have those tabs spot-welded on.

Re: "Point welding"?

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resistance welding



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