DIY Pulse Arc welding copper directly to cells

[devmonkey]

I've been working on a new handpiece for the welder that will be simpler to produce with improved reliability and ergonomics. Maintaining gas seals and allowing free retraction of the electrode whilst retaining a low resistance, low friction flexible high current connection onto the electrode has been challenging but this design is now fairly reproducible. I have sent out RFQs for the internal CNC brass parts that I would need to make a short production run.

 

[devmonkey]

Testing the new hand piece 0.3mm copper onto 0.2mm steel, 50J

 

[Etienne]

I wish I had this incredible tool in my workbench to make perfect weld and eliminate the risk of damaging cells.
Any update on your prototype, do you anticipate releasing something soon?
As an alternative would there be available TIG welders that would be safer than spot welder? I have no prior experience in spot welding, and a bunch of cells is on its way to my house tomorrow..

 

[devmonkey]

I used my welder to build a 16S4P EVE 40PL pack this morning. Was very quick, I don't think I spent longer than 15 minutes actually welding, I think the cycle time can be at least halved as well. I used 0.3mm copper and 70J welds, 3 welds per cell for ~6mm^2 fusion area per cell which is plenty.



Electrode is still shiny afterwards, i.e. no contamination.

 

[devmonkey]

Video of the process

 

[ahowell024]

I have been watching this for a month or so and trying to get as much information about this….
But I really like what you are doing here.

 

[ZEUS-FL]

This is a Fantastic Job !!!! If you decided making it in production please let me know I will find the clients for you !!

 

[Zambam]

Video of the process

Nice video! Near the end, I see soldered wires. Can you spot weld copper crimp terminals (examples below) to the pack instead of soldering?

https://www.digikey.com/en/products/detail/molex/0192210410/3187801?gad_source=1&gad_campaignid=20234014242&gbraid=0AAAAADrbLlgzYwiDNzkwM8gDM5ikkwncl&gclid=CjwKCAjw24vBBhABEiwANFG7yxWCJId9IKJ8Eqb3Dz0RnClSt6IBridHw2MvK4icVrc211l5zpeuMxoChvgQAvD_BwE&gclsrc=aw.ds

https://www.gordonelectricsupply.com/p/Penn-Union-Sl-25-10Awg-1H-Cop-Term-Lug/6073668?utm_source=google&utm_medium=shopping&utm_campaign=catch-all&gad_source=1&gad_campaignid=21890440937&gbraid=0AAAAAD8Z3WHGdmRM1otNoqVabr3aKm6y_&gclid=CjwKCAjw24vBBhABEiwANFG7y6u7daEjdku4Sn4ckD7teskOHOd4KN3tnpjwOgsOksFHtSg3xRhtFhoCPvMQAvD_BwE

 

[devmonkey]

Nice video! Near the end, I see soldered wires. Can you spot weld copper crimp terminals (examples below) to the pack instead of soldering?

I soldered the cables to the copper then welded the copper to the battery

I don't know how or why you would weld that style of crimp to a battery they are intended for terminating cables. You could certainly weld some sort of terminal on if it has a nice flat area to place the welds onto.

 

[Zambam]

I soldered the cables to the copper then welded the copper to the battery

I don't know how or why you would weld that style of crimp to a battery they are intended for terminating cables. You could certainly weld some sort of terminal on if it has a nice flat area to place the welds onto.

I wonder if you can get crimp terminals w/o the hole so it can be spot welded with your machine? I suppose the lug hole is preventing the shielding gas from doing its job? It'd be nice not having a soldered termination.

edit: With copper flux and the right resistance spot welder, those copper lugs can be welded to copper per this video.

 

[devmonkey]

I wonder if you can get crimp terminals w/o the hole so it can be spot welded with your machine? I suppose the lug hole is preventing the shielding gas from doing its job? It'd be nice not having a soldered termination.

edit: With copper flux and the right resistance spot welder, those copper lugs can be welded to copper per this video.

You can terminate however you like, I can easily weld the ring end of a lug terminal onto copper, it is just a bad idea. I thought you meant the tube end. If you want to crimp then roll the copper around the cable, hydraulic crimp, then wekd the tail to the cells.Never try and crimp something you have already welded or soldered, crimping will obviously distort and likely fracture the material.

 

[Zambam]

I can easily weld the ring end of a lug terminal onto copper, it is just a bad idea.

Good to hear your welder can do that. Why is it a bad idea? Crimp is better than solder for high current connections. Crimp the wire to the ferrule, spot weld the ring terminal to the busbar. As long the busbar is strong enough mechanically, what's the problem?.

 

[devmonkey]

Good to hear your welder can do that. Why is it a bad idea? Crimp is better than solder for high current connections. Crimp the wire to the ferrule, spot weld the ring terminal to the busbar. As long the busbar is strong enough mechanically, what's the problem?

I think you can make a crimp for welding many times more suitable than a ring terminal. For a start something with a decent weld area so you can get a load of fusion area. Anyway I think this is getting off topic. It is also possible to weld the cable straight to the copper.

 

[Zambam]

I think you can make a crimp for welding many times more suitable than a ring terminal. For a start something with a decent weld area so you can get a load of fusion area. Anyway I think this is getting off topic. It is also possible to weld the cable straight to the copper.

The reason I chose the 2 crimp terminals as examples is because they are available and inexpensive. Who wants to make a "crimp for welding"? I doubt one can easily make a round crimp ferrule that is airtight like the examples.

I do not like soldered high current connections if it can be avoided. Can you do a video demo of welding 8 gauge silicone insulation copper wire onto copper busbar?

 

[devmonkey]

The reason I chose the 2 crimp terminals as examples is because they are available and inexpensive. Who wants to make a "crimp for welding"? I doubt one can easily make a round crimp ferrule that is airtight like the examples.

I do not like soldered high current connections if it can be avoided. Can you do a video demo of welding 8 gauge silicone insulation copper wire onto copper busbar?

Nope you need a different weld head for anything other than.cell tab welds / sheet welds for which my weld head has been designed, checkout the commercial sunstone pulse arc videos if you want to see what can be done with a normal pulse arc weld head to stranded copper. This isnt likely to be a priority for me anytime soon albeit such a weld head would be much simpler than the cell weld head, basically just a solenoid. The same welder can be used.

Fyi crimp lugs are just squashed copper tube with a hole drilled, you can make them any size you like using a vice and for welding just don't drill the hole. You need to maintain the combined area of the cell welds up through the connection otherwise you are bottle necking the current. If you must use a ring lug then bolt it on to maximise the area.