Can Sunkko spot welder be used to weld pure nickel strip onto another pure nickel strip?

I bought the Sunkko 737G+ spot welder (which should be quite powerful when compared with the other Sunkko models) recently for building my first diy battery pack. So far from my testing, at about 75% power setting, welding with 0.2mm pure nickel strips onto cells is no problem.

But for the series connection, if pure nickel strip is used for maximum current purpose, then that series pure nickel strip will be welded onto the parallel pure nickel strip. The seller had told me that pure nickel strip cannot be welded onto another pure nickel strip. But from youtube (https://www.youtube.com/watch?v=ublFs7IU05c&t=683s), I saw he welded pure nickel strips onto pure nickel strips easily with a Sunkko spot welder just at about 50% power setting. Therefore, I tried with mine at 75% power setting but I failed.

I have heard that Sunkko spot welder is not that reliable. I have not started welding my battery pack yet. I do not want it break down before I finish my pack, so before trying mine at 100% power, I would like to check here if anybody got successful experience in spot welding pure nickel strip onto another pure nickel strip, especially with Sunkko welders.

If that is not possible, for the series connection, I will try to use nickel plated strip first and then on top of the nickel plated strip I will weld another pure nickel strip. Is this a good way and/or possible way to increase the output current of my pack?

Have you tried to increase welding time?

krlenjuska said:

Have you tried to increase welding time?

Click to expand...

I set the current at 80 and pulse at 12. I guess welding time is the pulse.

tmho said:

krlenjuska said:

Have you tried to increase welding time?

Click to expand...

I set the current at 80 and pulse at 12. I guess welding time is the pulse.

Click to expand...

Sorry i thought you have some potentiometer for welding time. I have home made spot welder with chinese controller and i can weld nickel to nickel without issues. I need more amps of course but no problem so far.

Try to increase pressure to your nickel if you can.

krlenjuska said:

tmho said:

krlenjuska said:

Have you tried to increase welding time?

Click to expand...

I set the current at 80 and pulse at 12. I guess welding time is the pulse.

Click to expand...

Sorry i thought you have some potentiometer for welding time. I have home made spot welder with chinese controller and i can weld nickel to nickel without issues. I need more amps of course but no problem so far.

Try to increase pressure to your nickel if you can.

Click to expand...

Thank you. I will try that later.

Works with 709A. Mine required all pulses and the knob at 6-7. Don't forget that you get higher power right at the machine. So if the hand-held tool doesn't have enough ''chooch'', just weld with the tips at the front of the machine.

Why bother with Sunko's, just get an Arduino lipo welder to do the business.

tmho said:

krlenjuska said:

tmho said:

krlenjuska said:

Have you tried to increase welding time?

Click to expand...

I set the current at 80 and pulse at 12. I guess welding time is the pulse.

Click to expand...

Sorry i thought you have some potentiometer for welding time. I have home made spot welder with chinese controller and i can weld nickel to nickel without issues. I need more amps of course but no problem so far.

Try to increase pressure to your nickel if you can.

Click to expand...

Thank you. I will try that later.

Click to expand...

Today, I tried spot welding 0.15 pure nickel strip onto another 0.15 pure nickel and the result is acceptable. The setting was pulse 10, current 70. Last time I failed and the setting was pulse 12 and current 80, which was a higher power setting. I guess this is because today I have followed your suggestion of increasing the pressure.

Today, I have also tried spot welding 0.2mm pure nickel strip onto another 0.2mm pure nickel strip. The result is not okay and the setting was pulse 14, current 80. I may try using higher power later when I have time.

multifrag said:

Works with 709A. Mine required all pulses and the knob at 6-7. Don't forget that you get higher power right at the machine. So if the hand-held tool doesn't have enough ''chooch'', just weld with the tips at the front of the machine.

Click to expand...

Thanks for your reply and suggestion. Please advise the thickness of the pure nickel strips you used.

tmho said:

multifrag said:

Works with 709A. Mine required all pulses and the knob at 6-7. Don't forget that you get higher power right at the machine. So if the hand-held tool doesn't have enough ''chooch'', just weld with the tips at the front of the machine.

Click to expand...

Thanks for your reply and suggestion. Please advise the thickness of the pure nickel strips you used.

Click to expand...

Usually 8x0.15, but used 8x0.20 also.