Can I spot weld copper strips?

DC carries more power for a given time than AC.
0.1mm cu is doable with a .3ni capable machine
Slots are a given, and discussed elsewhere in detail
Thicker than .1mm cu requires so much power you are approaching the limit of the can to survive. Any minor misalignment etc results in a hole perforating your cell, though It can be done with techniques other than spotwelding.

kdog said:

DC carries more power for a given time than AC.
0.1mm cu is doable with a .3ni capable machine
Slots are a given, and discussed elsewhere in detail
Thicker than .1mm cu requires so much power you are approaching the limit of the can to survive. Any minor misalignment etc results in a hole perforating your cell, though It can be done with techniques other than spotwelding.

Click to expand...

I read that 0.1mm copper is so much softer than 0.1mm steel/nickel which hold my pack together pretty good.
What are the other techniques you were talking about?

rg12 said:

rojitor said:

First post of the thread. Scroll down to disclaimer. Instructions there.

Click to expand...

Talked to the guy and he said that you actually did weld 0.1mm copper but he also said that he doesn't recommend it.

I'm buying this only for the purpose of welding 0.1mm copper.
Will it last?
Can you weld copper with copper electrodes? because I've seen that the big machines for copper use tungsten electrodes...
Can I use tungsten in this thing?

Click to expand...

Yes aulakiria does not support it as the machine was designed for nickel. If you read my thread I do not recommend it either.

rojitor said:

"The machine is copper welding capable but requires 4s lipo. That is dangerous for the machine and yourself. The intense use of 4s lipo on high flux times may cause premature failure of the machine. Use it at your own risk.
copper times are:
0.1 5-6 ms x2
0.2 10-12 ms x4
Do not use copper unless you know what you are doing.
The use of gloves and glasses are mandatory."

Click to expand...

I said clearly many times that copper 0.2 will kill the fets in no time and 0.1 could cause premature failure.
My machine is holding fine so far. I know the risks and I plan to keep welding 0.1 copper because it is worth it.

Is it true that 0.1mm is super soft compared to 0.1mm nickel plated steel?

Yes, 0.10mm thick copper sheet will crumple like paper.

Everyone who is interested in spot-welding seems to be familiar with the 0.15mm and 0.20mm thick nickel ribbon, they are pretty stiff.

For me 0.1mm nickel plated is strong enough (but not conductive enough).
Will 0.1mm copper be any difference?

The IACS scale measures conductivity of any material compared to pure copper. Copper is 100/100 on this scale, and nickel is somewhere around 25/100.

If you are using some type of cell end-caps that provides a strong physical connection, and your battery housing is also strong in order to protect the cells...the bus-bars only needs to conduct electricity, and 0.10 copper thickness is twice as good as 0.15 nickel, so it will handle more amps, or...it will run cooler at the same amps.

As seen on the chart the conductivity, resistance and thermal disipation totally beats nickel.
It's way more difficult to work with. The mechanical properties are very weak yet it is worth it in my opinion.

I have found a place in the UK that sells tinned copper tape 20mm x 0.1mm. Will the tinning make it any stronger/stiffer?
https://www.wires.co.uk/acatalog/tape_tc.html they also do silver coated Copper but only up to 3mm wide.
I wonder if they would consider manufacture of wider tapes?

https://endless-sphere.com/forums/viewtopic.php?f=14&t=84680&start=125
They talked about that there. I didn't test it so I have Nothing to say about it.

rojitor said:

rg12 said:

rojitor said:

First post of the thread. Scroll down to disclaimer. Instructions there.

Click to expand...

Talked to the guy and he said that you actually did weld 0.1mm copper but he also said that he doesn't recommend it.

I'm buying this only for the purpose of welding 0.1mm copper.
Will it last?
Can you weld copper with copper electrodes? because I've seen that the big machines for copper use tungsten electrodes...
Can I use tungsten in this thing?

Click to expand...

Yes aulakiria does not support it as the machine was designed for nickel. If you read my thread I do not recommend it either.

rojitor said:

"The machine is copper welding capable but requires 4s lipo. That is dangerous for the machine and yourself. The intense use of 4s lipo on high flux times may cause premature failure of the machine. Use it at your own risk.
copper times are:
0.1 5-6 ms x2
0.2 10-12 ms x4
Do not use copper unless you know what you are doing.
The use of gloves and glasses are mandatory."

Click to expand...

I said clearly many times that copper 0.2 will kill the fets in no time and 0.1 could cause premature failure.
My machine is holding fine so far. I know the risks and I plan to keep welding 0.1 copper because it is worth it.

Click to expand...

I thought about making the parallel connections with 0.15 pure nickel and the serial connections with 0.1mm copper with the device you have.
The problem is that the copper is going to be spot welded on top of the 0.15 pure nickel which is a much better conductor than the body of the cell.
I know that since it take about half as much power from my spot welder to spot weld 0.15 pure nickel to the cell than what it takes to spot weld 0.15 pure nickel on top of another piece of 0.15 pure nickel.
So I'm afraid that the copper wouldn't stick to the pure nickel...

Copper sticks on nickel but you must do it well or it will become weak. 4s lipo and a very nice contact and some pressure needed. It can be tricky Sometimes.
As I said copper has some difficulty.

rojitor said:

Copper sticks on nickel but you must do it well or it will become weak. 4s lipo and a very nice contact and some pressure needed. It can be tricky Sometimes.
As I said copper has some difficulty.

Click to expand...

If I place it on top of nickel, wouldn't the nickel lower the conductivity since the copper is on top of the nickel?

The conductivity in parallel is irrelevant. What matters is series. That's where you need high power transfer. Copper on nickel is not a Major issue. It is widely used for skateboard packs. Since they need to be flat and flexible it is very common to solder copper wire to make series between blocks.
Solder those tinned copper tabs we just mentioned for series could work very well too.

The positive and negative caps on each 18650 cell are nickel-plated steel. Realize that steel is a worse conductor than nickel, but...the distance from the inside of the cell to the outside is very short. If you overlay copper on top of the nickel ribbon, the majority of the electricity will take the path of least resistance. It's true that the current must pass through the nickel bus-strips, but the distance between the cell-tip and the copper will be short.

spinningmagnets said:

The positive and negative caps on each 18650 cell are nickel-plated steel. Realize that steel is a worse conductor than nickel, but...the distance from the inside of the cell to the outside is very short. If you overlay copper on top of the nickel ribbon, the majority of the electricity will take the path of least resistance. It's true that the current must pass through the nickel bus-strips, but the distance between the cell-tip and the copper will be short.

Click to expand...

Thanks alot.

rg12 said:

I'm afraid of the corrosion thing...there is always a chance of humidity getting in...
I will need a bad ass spot welder for that I'm guessing because mine is maxed out when using 0.15 pure nickel.
Do you have any suggestions for a machine that isn't expensive from AliExpress that is strong enough?

Click to expand...

Maybe you could vacuum bag your entire battery after it is welded up? A standard house hold vacuum sealer could do the trick.
As for cable exit use the same "gum" used for vacuum infusion molding. It will create an air tight barrier around the cable exit from your vacuum bagged battery. Use over sized cable as thick as possible between battery and controller to avoid heating and metal expansion that will ruin the air tight barrier around the exit cable.

As long as you have drawn a vacuum there should be close to none oxygen inside the vacuum bag, and oxygen is what makes copper corrode. No oxygen = no corrosion. To double up on safety you could either consider using plated copper strips or if that does not take away from the coppers conductive properties in regards to current handling, or maybe some petroleum vaseline on top of copper before vacuum bagging.

If you put enough strain on your battery after vacuum bagging it, temperature will rise inside the bag and could cause vacuum bag to expand enough to break seals either in bag itself or the wire exits. If that happens reseal battery after a a good cleaning of battery and copper.

I would rather spray the copper strips with some transparent protective varnish for PCB like this:
http://www.ebay.it/itm/VERNICE-PROTEZIONE-CIRCUITI-STAMPATI-PCB-UNIVERSALE-PELLICOLA-ISOLAMENTO-SPRAY-/281756224249

Is there any drawback using it?