Bad weld from spotwelder

[kocetoMR]

spot welder

20201016_210956.jpg (482.52 KiB) Viewed 235 times

one side is good ,other side is poor.
Spot welder is from 2P2S supercap 2.8V.Check the cable and connection,they are good.

What can be the problem?

[kocetoMR]

capacitors

1602872910529.jpg (93.5 KiB) Viewed 233 times

[kdog]

Minor variation in electrode pressure or electrode tip shape would be my main guess in that order. My spotwelder is AC so I'm not sure about DC, but welders pay attention to polarity of their workpiece, try swapping tip polarity and see if it reverses. Can't think of anything else ottomh.

[kdog]

Have you tried actually spotwelding some nickel?looks like you're just hitting the can there.

[kocetoMR]

every time when start weld needle neet luke like this

20201017_172343.jpg (215.16 KiB) Viewed 184 times

every time when start weld needle neet luke like this

[spinningmagnets]

Get some old bad cells, even disposable D cells will work. Use some nickel scrap and weld onto the scrap batteries. The longer path will add more resistance.

Nickel bus, and nickel-plated steel are very good for the parallel connections. For the series, I like the nickel-sandwich method.

viewtopic.php?f=14&t=108006

[kocetoMR]

cooper strip

20201017_213659.jpg (475.22 KiB) Viewed 166 times

i use sandwich method in many battery pack.In my country copper is with high %gold and is difficult to weld direct to cell with sandwich method.