Solder tabs on A123 batteries

[oscillator]

Just opened up a new A123 pack and the solder tab for the + lead fell off. Soldering directly to the cell doesn't work. How does one re tack weld or otherwise electrically attach to the cell once the tab is off?

:arggg:

[oscillator]

anyone?

I've tried sanding the top with a drum sander but this didn't help.

[WayneBrown]

most cells the tabs are tack welded, and are not repairable.
No matter what, it won't be reliable.

[bankyf]

Do you have a Batteries Plus near you? They have the machine to weld the solder tabs back on.

[oscillator]

Wayne,

actually I think the tack welds are unreliable. Running high currents through 4 tiny spot welds gives me great concern. Since all the cells are in series on a 10 cell A123 pack, it would only take the spot welds on one cell failing and you would have zero power - not even power for the RX an servos. No chance even to auto.

Searching the net I have found aluminum powder solder that is supposed to work for this application. I also found a site were someone stacked and soldered the cells in series, as well as used battery bars. Check this out:

http://www.slkelectronics.com/DeWalt/packs.htm

bankyf,

Looks like I have one 25 miles from my house. If all else fails I'll give them a try, but I really hate the spot welds.

Thanks.

[WayneBrown]

I fooled with the aluminum solder, and found it lacking in several areas. You'll have to trial and error a few connections to get it right repeatedly, and is the reason I did not mention it.
I hate to reccomend something that I have a hard time making work, and would not be able to reliably convey how to do it properly.