Maintenance/Troubleshooting Chinese Spot Welder

[msebold]

New to spot welding and need some help with welder maintenance/troubleshooting.

Recently got a cheap Chinese "Sunko" combination spot welder and soldering station. I completed about 100 welds (with the hand-held unit) welding nickel tape to the negative terminals of various parallel clusters of my Tesla 18650 cells. Upon starting to weld nickel tape to the positive terminals I notice that the weld quality suddenly has become very poor. The welds just are not holding. I've tried cleaning the welding tips with emery paper but to no avail. The tips, which are very tiny, have not really mushroomed, but they are also not pointy.

1. Anybody familiar with one of these types of spot welders able to give any trouble shooting advice?
2. The welder comes with only 1 set of replacement welding tips for the hand-held unit. Any ideas on where I might find, or what I might use for additional replacement welding tips? These welding tips appear to be simply a solid copper wire, but again I am new to spot welding and these spot welders.

Any help appreciated.

Thx in advance.

 

[msebold]

Okay. Let's make this easier. Who has a favorite battery tab spot welder they want to brag about or recommend -- whether it be a particular brand, model, or a simple DIY contraption (by "simple" I mean simple enough for a dummy like me to build)?

What's simply the best battery tab spot welder a poor guy like me can buy/make?

 

[Syonyk]

I'm perfectly happy with my 788+, after replacing the triac that blew up within about half an hour of operation.

Did you change the nickel strip you were using? The nickel coated steel requires a lot more power to weld than the pure nickel, and tends to spark while welding.

I've done thousands of spot welds on my original set of tips without replacing them. They're not as sharp, but still seem to work fine. I do believe they're a harder tungsten copper or something, not just plain copper wire.

If welding power is down, you may have a partially burned trace or something internally, or a loose connection - pop it open and take a look.

As far as alternatives? Nothing in the same price range... I want a nice pneumatic unit, but they're a few grand.

 

[msebold]

Thanks Syonyk. I appreciate the input regarding the copper welding tips. I didn't think they looked worn out. They just don't seem to have the same "zap" they had 100 welds ago. Perhaps I do have something wrong internally. I'll try to check it out. BTW I am using pure nickel tape, not nickel plated steel.

 

[redilast]

Did you change the nickel strip you were using? The nickel coated steel requires a lot more power to weld than the pure nickel, and tends to spark while welding.

Nickel plated steel requires a lot less power than pure nickel. This type of welding is resistance welding so more resistance = easier to weld, which is exactly why on most commercial packs you will see cutouts between the spot welds, which forces the weld power to go from one electrode through the top of the cell can and to the other electrode, rather than just jumping from the surface of the weld material from electrode to electrode.

 

[sonnetg]

How thick are the nickle plates? I have a generic spot welder which does a lousy job with 0.15 mm thick nickle plates, but works great with 0.1 mm thick strips. To get around this I double the welds. It's twice the work, but gets the job done..

 

[tomjasz]

Mine crapped out far sooner. They sent me a new pcb and a couple of parts they thought could be suspect. It all sits in a box since I've been unable to find any assistance. Or get anyone to pay the $65 they charge for the pcb and parts.

But I guess 6 running bikes 8 batteries, and only one ripoff isn't to bad a record.