Spot welder doesn't work with 0.15mm pure nickel

Hey Guys,

I've been using my Sunkko 788+ for about a year now with 0.1mm nickel plated (steel) strips and I used barely half the power of the thing and the welds are super strong.
Just got my 0.15mm pure nickel strip (tested it to be pure nickel also using some testing guides from google) and even in the highest setting the tab can be pulled with medium force.
The highest setting makes the tab red around the weld area for a second, meaning that it gets hot as hell but still doesn't connect well.
The biggest problem is nickel to nickel (when connecting cells in series), while trying to weld pure nickel strip on top of another nickel strip it doesn't connect at all even at the highest setting that gets the tab red hot!
* I'm using double pulse btw, which is the highest pulse number my machine has.

I was reading the description of the Sunkko 709A on eBay and it said that it can weld up to 0.3mm and if it's pure nickel then up to 0.15mm which makes sense.
The thing is, since my Sunkko 788 got the tab red hot and still didn't connect, will the 709A have any potential of working with pure nickel as advertised?
The only reason it MAY work is because it has up to 8 pulses which mine has only 2 but again, mine got the tab red hot and didn't connect so will more pulses work for me?

Thanks,
Roy

Sunkko 709A is much more powerful 1900W
but you need exlactly this model: https://www.youtube.com/watch?v=dV84EIKXz5Y&t=17s

Are you using a central slot on the ribbon over each cell?

If not it can be cut with a dremel and a thin abrasive wheel.

kocetoMR said:

Sunkko 709A is much more powerful 1900W
but you need exlactly this model: https://www.youtube.com/watch?v=dV84EIKXz5Y&t=17s

Click to expand...

The model in the video is not 709A, it's a different one.
709A has 1900w but what the hell does it mean? these things go up to hundreds of amps for a fraction of a second, something that will result in much more than 1900w.
If the 709A is 1900w then how much is the 788+?

All of these welders are under powered for the job.
Some things you can try. Take out the welding tips and sharpen them up, the smaller the contact the hotter the weld.
The copper used to weld with may be low quality and may need to be filed every few dozen welds.
Try also reducing the pressure the less pressure the better but be carful not to reduce pressure too much, if the tab lifts off the cell it will vaporize.

If your nickel is glowing red hot, this is bad bad bad. I'd say that it is too weak (too few amps) and that it is using a long pulse time to try and weld which means lots of heat going into the battery.
A slot is your only hope. If this doesn't work then you'll have to go .1mm layered up.

Red hot = low amps? sounds like the opposite, like you said, too long of a pulse.
How slotted tabs are better?

I will try also shappening the copper tips because they are pretty round right now.

Don't you think that the 709A that has up to 8 pulses will help? it is the same size as my current machine but has 8 pulses instead of my 2 pulses.

For spot welding on a battery, you want to create a local intense heat right at the tip (weld zone) and then terminate the power before the heat can spread. For this you need high amps for a short time. This creates a small localised molten nuget that cools almost instantly. Too little amps ( I'm still talking hundreds ) make the area hot, but not hot enough to weld quickly, so a longer pulse time is needed. The excessive heat spreads out damaging your battery. If you take it to the extreme, you get a large searingly hot area with no weld. This is battery death in an instant.
When I weld nickel I see no redness except the odd ejected sparks of metal, and as quick as I can touch it there is only mild warmth if anything. If you are getting red hot nickel it's too thick for your machine.
Read up in nobuo's repository about the slot effect - it's all there.

I don't like the slotted ones as I'm used to the long strip that I can cut to the length that I need.
I guess I will try sharpening the tips of the copper and if it doesn't work I will order the machine with the 8 pulses because one step above that is a big and expensive machine that works on automatic mechanial/air pressure to touch the strip and that is way over my budget.

I want quality welds you need a powerful machine-=5kW
I recommended this: https://item.taobao.com/item.htm?id=533235971493
use taobao agent for shipping!

Just ordered the 709A since I don't need much more power rather than more pulses since my little machine can burn even the pure nickel tab.
Mine has 2 pulses and the 709A has up to 8 so will try that...

I just received my 709A. It came with some .01 plated strips. With the hand held it need 2x the the power due to the length of the cable, in other words, full power. Possibly the contacts on my handheld are oxidized and need some sanding with emery paper. It is recommended that you NOT use pure copper as the anode, use the copper/aluminium contacts.
Attached is the instructions for the 709A that were posted on the internet,,,,somewhere.

RootedSuperuser said:

I just received my 709A. It came with some .01 plated strips. With the hand held it need 2x the the power due to the length of the cable, in other words, full power. Possibly the contacts on my handheld are oxidized and need some sanding with emery paper. It is recommended that you NOT use pure copper as the anode, use the copper/aluminium contacts.
Attached is the instructions for the 709A that were posted on the internet,,,,somewhere.
2017-02-13_035023.jpg

Click to expand...

Hi, I also want to buy this one. But usually the Sunkko post will mention tht it need circuit breaker of 40A or above. In Canada, the normal power outlets are just with 15A breakers. I worry that it will trip my breakers. Do you have trouble with that? Is your 709A for 220V or 120V?

tmho said:

Hi, I also want to buy this one. But usually the Sunkko post will mention tht it need circuit breaker of 40A or above. In Canada, the normal power outlets are just with 15A breakers. I worry that it will trip my breakers. Do you have trouble with that? Is your 709A for 220V or 120V?

Click to expand...

dont buy one. spamming multiple topics with the same questions is not needed. i gave you a link to a superior device (and cheaper) in another topic.

I have 787A+
Sometimes If i switch on the welder it welds very poorly. Strangely sometimes when i switch it off and on again then suddenly all welds doing ok. Max is 0.15 pure nickel or barely 0.2mm ni-plated steel.
I use multiple layer 0.1mm pure nickel just to be sure. And solder extra copper strip on top of it for crazy high current racing packs. :wink:
Best is 60 2 setting for me. Over and under that doesn't weld good.

I think MOT + SSR + foot switch are better option and basically free too.

tmho said:

RootedSuperuser said:

I just received my 709A. It came with some .01 plated strips. With the hand held it need 2x the the power due to the length of the cable, in other words, full power. Possibly the contacts on my handheld are oxidized and need some sanding with emery paper. It is recommended that you NOT use pure copper as the anode, use the copper/aluminium contacts.
Attached is the instructions for the 709A that were posted on the internet,,,,somewhere.
2017-02-13_035023.jpg

Click to expand...

Hi, I also want to buy this one. But usually the Sunkko post will mention tht it need circuit breaker of 40A or above. In Canada, the normal power outlets are just with 15A breakers. I worry that it will trip my breakers. Do you have trouble with that? Is your 709A for 220V or 120V?

Click to expand...

Does not trip the house breaker, It's a microsecond of pulse, nothing really for draw.
I've changed from strips to .01 sheet, other than eSk8 packs, that are flat.
I might make a length of wire for the hand piece with 6awg high temp silicone wire. It might perform better than the stock OFC speaker wire used.