View Full Version : Solder tabs on A123 batteries
01-26-2007, 09:02 PM
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?
01-27-2007, 03:26 PM
I've tried sanding the top with a drum sander but this didn't help.
01-27-2007, 03:42 PM
most cells the tabs are tack welded, and are not repairable.
No matter what, it won't be reliable.
01-27-2007, 03:44 PM
Do you have a Batteries Plus near you? They have the machine to weld the solder tabs back on.
01-27-2007, 05:04 PM
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:
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.
01-27-2007, 05:17 PM
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.