Tab Welding tests

Tab welding tests

Not So easy to Tab weld batteries!!!

After two days of tests with different batteries, electrodes and welding materials. Here are our results.
Batteries tested : K2 Energy (Steel), A123 (Aluminum)
Tab Material tested: Copper (5mils,10mils,12mils), Nickel ( 5mils, 10mils, 12 mils)
Electrodes: Copper, Tungsten

We first tested copper tabs (with Copper Electrodes) because we preferred to go with the most conductive material and the cheapest. However we were never able to make any welds. The electrodes would stick to the copper, but not to the batteries. We tested all thicknesses, different power outputs, sloted copper, even stepped tab welding (one electrode on the tab, the other directly on the battery). Also, one electrode would blast through the copper most of the times (pic2).

Then we tested tungsten Electrodes to see if we could tab weld cooper. Nothing worked, the electrodes welded to the copper but not to the batteries(Pic4). We don't want to make any conclusions with the tungsten electrodes because are setup was far from ideal(Pic6), because of the diameter of the electrode the contact might not be big enough to pass all the current. We will modify the electrodes to do more tests.

The next tests were with Nickel tabs and copper electrodes. This is where we achieved the best results.. With a little adjustments we got great tab welds (bizarrely I don't have a pic of them). 5mils thick Nickel tabs are too thin, 10mils achieved the best result for our setup.

P.S: I want to specify that none of us are Tab welder experts and that we may be doing something totally wrong, but we don't know what!