# Sunkko Spot Welder Advice??



## power_aziz (Jan 23, 2019)

Hello all,


I'm working on building a battery pack for a college EV project. I've been assembling it using 0.15 mm nickel strip between cells. The last spot welder I had (Sunkko 788H) died on me after I accidentally exceeded its duty cycle (which was never published). 



I'm looking to purchase the Sunkko 709AD to use its spot welding pen, and saw that the 220 V version has much better performance from reviews. However, there are two potential issues...


1) The 220 Volt version is listed as non-US and states that it operates at 50 Hz AC.


2) The plug style of the 220 volt version is Australian instead of NEMA standard. 



Does anyone know workarounds or if there's a way to connect this to a US 220 V 60 Hz main? 



I've seen review videos where it's been done but I'm not sure what hazards this presents....


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## MattsAwesomeStuff (Aug 10, 2017)

> Does anyone know workarounds or if there's a way to connect this to a US 220 V 60 Hz main?


It's hard to know exactly without seeing inside, but...



> 2) The plug style of the 220 volt version is Australian instead of NEMA standard.


That's the easy part. That's just a mechanical, it's just the shape of the plug, there is nothing electrically different. Lop the end off, go to a hardware store, buy an extension cord end, and put that on instead. Or just unscrew the case and remove the whole cord and replace it with the cord from any suitably-sized junk appliance.



> 1) The 220 Volt version is listed as non-US and states that it operates at 50 Hz AC.


Short version: It's probably fine.

This part is a guess, but since the device weighs 15.6 lbs, that's pretty heavy for such a small bit of electronics. I suspect the method by which the spot welder discharges is just a step-down transformer (transformers are heavy), not capacitive discharge or transistor based.

If it's a transformer based, it's too hard to control the output (it's switching currents on par with electric vehicles), so they control the higher voltage input to the transformer instead, probably with a TRIAC.

I can't tell how you set the power, if you set the number of pulses, or if the dial that says you're setting current isn't actually doing that, it's just the number of pulses. That is, I don't know if you have control over 2 variables (both current and duration) or just 1 variable (only duration, at max current).

Typically how a TRIAC would work for variable current is to take advantage of the AC waveform. 60hz AC is a wave that goes up then down, cycling 60 times per second. Each time it switches from positive to negative or negative to positive, the TRIAC shuts off. To get the TRIAC to turn on, the control electronics give it a short pulse, and then it stays on until the next time the voltage flips. So if you want it to be on 100% of the time, you make sure you re-trigger it every time it crosses zero, immediately. If you want it to be on 50% of the time (half power), you delay before turning the TRIAC on after each cycle, until half the cycle is gone. For less power you'd delay even longer, for higher power, you'd delay shorter. Since this happens rapidly (120 times per second for 60hz, counting both positive and negative halves of the cycle), it's effectively averaged out and doesn't feel like 120 different delayed pulses, it just feels like an average.

If that's how it works, then changing from 50hz to 60hz is shortening the time periods for the TRIAC triggering. You're packing more cycles in per second, meaning each one is shorter. That means if you have a power dial, that, behind the scenes is just delaying the triggering of the TRIAC each cycle, you will hit 0% power when you reach 20% (because the next cycle has already started, as the cycles finish faster). That would mean if the dial originally went from 0-100% (it might not, it might just scale a portion of it, maybe 60-100% and the dial all the way to minimum is still 60%), then below 20% is zero. It just affects your interaction with the dial, and I'd say that it's minimal. You're not measuring anything, you'll turn it up for more and down for less.

...

If the dial is not current control, but just pulse control, then the same thing is probably happening behind the scenes, you're just not being exposed to it. Regardless, I doubt the pulses are actually 1/100th of a second, that's too short, so it probably has a fixed amount of time it turns on for each cycle. Maybe "a pulse" is 10 AC cycles, and if you set the dial to 8 pulses then it's turning on (at 100%) for 80 cycles in a row. Maybe something like that. That is probably not affected by the difference between 50hz and 60hz, depends if it's counting cycles or counting time directly, but, in any case, all you'd see is a 20% swing in something.

...

Transformers can handle more power, roughly linearly with the frequency given to them. So, at 60hz you might be 20% more powerful than at 50hz. I suppose there's a small chance that it might blow the fuse on the device but I doubt it.

...

All the digital stuff won't matter, since the first thing it'll do is turn your 50hz or 60hz into DC anyway. The power supply will be slightly cleaner running at a higher frequency but that won't impact you.

...

If the whole device is transistor-based it will still have a transformer but it won't use it directly like this. I don't think it would matter between 50hz and 60hz.

...

Ways that 50hz vs. 60hz matter is usually for things like induction motors which will spin 20% faster.

It might even be the case that this device is sold in 5 different regions where the only thing that differs is the type of cord they put on it.


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## power_aziz (Jan 23, 2019)

@MattsAwesomeStuff


Thanks for the input and in-depth explanation! Yes, from stripping down my old spot welder that broke, the system is indeed a transformer controlled by a TRIAC. 


There is a current selector input, but like you mentioned, it's not clear whether it is directly controlling current+duration or only duration.


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## BVH (Jul 4, 2014)

Here's an alternative to the Sunkko you might want to check out. I have a Sunkko but came across this spot welder that I think performs far better.

https://www.endless-sphere.com/forums/viewtopic.php?f=14&t=89039

It's a long thread but well worth the read. In short, this spot welder delivers the precise amount of energy (Joules) that you specify into each weld. Dial in the Joules you want and it will vary time and current to provide the exact energy you specify in one pulse. It will also read out exactly what was delivered (milliseconds and current) to accomplish this after each weld if you keep the pedal down. It will alert you if the weld failed. It is quite sophisticated. I really like it. You can buy it ready assembled and buy a plastic case for it that you will have to glue together. Read the last 10 pages and you'll get a good feel for it. There's a few of these kit type spot welders out there but this by far, is the most technologically advanced.

Place to buy it:

https://www.keenlab.de/index.php/product-category/kspot-welder-kit/


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## MattsAwesomeStuff (Aug 10, 2017)

power_aziz said:


> Yes, from stripping down my old spot welder that broke, the system is indeed a transformer controlled by a TRIAC.


Let's just fix your old one.

What smells burnt or looks like it has shitstains on it?

Honestly it's probably just a fuse, or, a thermal fuse (sometimes hidden in-line in the input wires, hard to fine). $1 fix.

Even if you blew the transformer, a little bit of power cord an a bushbutton switch and you can make it manual triggered (toe-tap a foot pedal for duration of pulse you want).

If you can't find what's dead, I'm happy to run you through some really basic electronic CPR.


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## Jimbo69ny (Feb 13, 2018)

I have one. I’m not happy with it. I wish I didn’t waste the money on it. 

Here is my review. 

https://youtu.be/HSwXZ0H0uSY


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## MattsAwesomeStuff (Aug 10, 2017)

Jimbo69ny said:


> I have one. I’m not happy with it. I wish I didn’t waste the money on it.


It's spot welding. Consistent pressure is essential, as spot welding is a thermo-resistive process, not a thermo-plasma (arc) process.

Adding long cords to a cable carrying less than 1 volt is, well, should be obviously a bad idea. That's why all spot welders don't use cables, they use the arms themselves wherever possible. That's why the cables that come with them are short, and why it has electrodes mounted directly to the machine itself.

Whatever power the spot welder has a 1 foot, it has half that power at 2 feet, 1/3 that power at 3 feet, etc.

You can mitigate it a little by adding absurdly thick cables, but, yeah.

Looks like operator error to me.


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## Jimbo69ny (Feb 13, 2018)

MattsAwesomeStuff said:


> It's spot welding. Consistent pressure is essential, as spot welding is a thermo-resistive process, not a thermo-plasma (arc) process.
> 
> Adding long cords to a cable carrying less than 1 volt is, well, should be obviously a bad idea. That's why all spot welders don't use cables, they use the arms themselves wherever possible. That's why the cables that come with them are short, and why it has electrodes mounted directly to the machine itself.
> 
> ...



Matt, I recognize your screen name. I know you think you do everything right and I do everything wrong but adding the 2 gauge EV cables is the only thing that made this thing usable. Previously, it didnt work at all. Now it at least works.


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## MattsAwesomeStuff (Aug 10, 2017)

Jimbo69ny said:


> Matt, I recognize your screen name. I know you think you do everything right and I do everything wrong


??

Great of you to bizarrely be prejudiced and put words in my mouth, and then meanwhile at the same time not discuss reasons or facts.



> but adding the 2 gauge EV cables is the only thing that made this thing usable. Previously, it didnt work at all. Now it at least works.


By chance, do you understand how a spot welder works or what it is?

Adding resistance in the form of 2g extension cables does not make any sense.

If you had to extend the cables, then, okay, the heaviest cable you can find is appropriate, but, I think literally no one in the world does that to a spot welder. You keep the leads as short as possible for the task. If you're having problems with blow-through, then turn down the current.

I dunno, maybe I'm wrong, link to where you got the advice about adding cabling to it to improve performance.


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## Jimbo69ny (Feb 13, 2018)

MattsAwesomeStuff said:


> ??
> 
> Great of you to bizarrely be prejudiced and put words in my mouth, and then meanwhile at the same time not discuss reasons or facts.
> 
> ...



For those who dont know, Matt is always busting my balls telling me I am stupid... I am not putting words in his mouth, he is just a drama queen.



Yes Matt I know how a spot welder works. Yes Matt I know shorter leads are better. Yes Matt I know adding length adds resistance. 



The problem I had with the unit was not with blow through. I couldn't get it to weld anything to 18650 cells. I took the unit apart and the wires that go from the transformer to the welding cables inside the unit were very small. So I upgraded the whole thing with 2 gauge cables just to get it to work.


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## MattsAwesomeStuff (Aug 10, 2017)

Jimbo69ny said:


> For those who dont know, Matt is always busting my balls telling me I am stupid... I am not putting words in his mouth, he is just a drama queen.


You, are quite directly putting words in my mouth. You said "I know you think you do everything right and I do everything wrong".

I don't even have an opinion on you, I don't even know who you are.

*I'm* a drama queen?

Let's review this thread:
- Guy asked for help on a spot welder
- I gave an explanation of how the spot welder likely works.
- Guy confirmed that's how it works.
- I offered to help fix it.
- You posted a review and said it doesn't work for you.
- I watched your review and said your conclusion of adding several feet of extra cable doesn't make sense.
- You start making personal attacks and calling names.
- I try to ask you questions about the particulars and sources you seem so confident about.
- You keep name-calling.

Well, it does seem like there's a drama-queen in this thread. I don't think it's me.

I'm curious to read where you were getting advice that adding cable like you did was the solution. 

I've built 5 or 6 spot welders for people, so, it's not like I'm just talking out of my ass.


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## Jimbo69ny (Feb 13, 2018)

MattsAwesomeStuff said:


> You, are quite directly putting words in my mouth. You said "I know you think you do everything right and I do everything wrong".
> 
> I don't even have an opinion on you, I don't even know who you are.
> 
> ...



If anyone cares I encourage them to search Matt's previous posts on this page. Matt is always condescending, thinks that he is always right and his way is the only way. 



And no Matt, I didn't need anyone else's advice to know that upgrading tiny wires with larger ones was going to help my spot welder function better. I did it on my own accord and it worked.


I am glad that you helped the original poster. I was only offering my own help and advice as well.



This is my final post here. I am not wasting anymore time on this. Have a good day.


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## MattsAwesomeStuff (Aug 10, 2017)

Jimbo69ny said:


> If anyone cares I encourage them to search Matt's previous posts on this page. Matt is always condescending, thinks that he is always right and his way is the only way.


Umm, I can think of someone in this thread that that describes, but it's not me.



> And no Matt, I didn't need anyone else's advice to know that upgrading tiny wires with larger ones was going to help my spot welder function better. I did it on my own accord and it worked.


That's clearly false, in your own words.

You say right at the beginning of your review: "I saw another Youtube video in which someone had added beefier cables. I really just added I think two 7g cables to each lead. This here works perfectly fine right from the start, it was fine."

So, it wasn't your idea, you copied someone else's idea. But no, you came up with it yourself you say now. Okay.

I was asking for the source because I think I know why someone would suggest increasing the thickness of the cable, and I think you misunderstood why that worked. (My hunch is that they increased the thickness of existing cables, lowering the resistance and increasing the amount of power that can flow. Not... that they just inserted extra cable to add more length as you've done, which should have a negative effect). But maybe I was wrong and I'm curious to learn about their reasoning.

You say "The original cable was maybe 1 1/2' long, it was just hugely underpowered it didn't work well at all." ... and rather than replace it, you inserted an extension into it, which leads me to believe you think the power originates in the cable? It's completely nonsensical.

So, then what about this earlier statement?



> adding the 2 gauge EV cables is the only thing that made this thing usable. Previously, it didnt work at all. Now it at least works.


In your own words, there was nothing wrong with your spot welder (as demonstrated by the prongs on the unit itself working perfect, in your own words), only that you had trouble with the extension.

The extension is electrically identical to the prongs on the unit (they're in parallel, I presume), so the only thing that's different is the cable length (will show a linear power decrease the longer you go) and the way the operator is using them.

Other things you say in your video, after your "successful" modification:

- "It's so unpredictable"
- "Sometimes it sparks sometimes it doesn't"
- "Different cells require different settings"
- "I really hoped it was going to work a lot better than this"
- "It seems like each cell requires a different setting"

You got 3 out of 7 welds to stick.

What I think is much more likely is that the inconsistency you're seeing is not from cells somehow being so different as to require completely different welding settings, but from 3 things:

1 - A loose connection/terminal (with ~1v, any corrosion or poorly clamped connections will lose most of their power).

2 - Operator error. Especially, poor or inconsistent pressure, which we can see clearly in the video of you wobbling around using one hand. Spot welding is extremely sensitive to consistent, firm pressure.

3 - Dirty cells and dirty electrodes. Especially after you see a spark, that is the indicator for a bad weld. The spark means there was light which means that there was poor (narrow) contact and a bit of the electrode got super-heated and vaporized rather than welding, leaving oxidized remains of the electrode spattered all over itself, making the next weld also have poor contact.

...

I guess you're just going to say I'm a know-it-all who thinks only my opinion is right, but, a person could claim that about literally any time they're wrong about anything.

To elaborate a little bit on my experience with spot welding, in particular small scale and spot welding wires (as you were doing)... I briefly helped run a chainmaille manufacturing facility that had 5 automated machines each cutting/spotwelding 120 wire rings per minute, 24/7, and, ran a manual stitching machine to connect sheets together, and, ran a manual spot welder. And... partially designed (inspired?) the spot welder that company now sells specifically for that purpose.

To be fair, I didn't do it for very long. But the facility had been running for at least a decade by that point, and the owner and guy who maintains the machines told me, and showed me, that when you see a flash in the room, to stop and inspect that joint and clean the electrodes because that means a weld failed and subsequent ones will fail too until cleaned. You won't see a spark unless you vaporized electrode by doing something wrong.

So, my bad. That's only... 800,000+ spot welds per day. What do I know.

Ignore my advice. Jimbo knows best. Insert sections of cable into the middle of your electrode like literally no one else in the world does to spot weld something, and then still be bewildered by inconsistent results and blame the product.


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## Jimbo69ny (Feb 13, 2018)

Oh that's right, I think I did see a video from some one else who did the same thing. I guess you got me there, someone else also had to upgrade their wires too. I made that video around a year ago so I had forgotten.


I didnt read the rest of your post so I cant respond to anything else.


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## ballmatic (Apr 12, 2019)

Were you able to get this working? I am having the same problem since I got the 220v version and I'm in the USA. Thinking of cutting the wires and putting a different plug on but wanted to know if you did that and had success? Was the 50-60Mhz difference OK?


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## Jimbo69ny (Feb 13, 2018)

I gave up on it. I stopped playing around with it. I never got it running as reliably as I would like. I am currently giving it away on my YouTube channel.


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## MattsAwesomeStuff (Aug 10, 2017)

Jimbo69 said:


> I gave up on it.


I think he meant the OP, not you. Since, you didn't even mention any plug modifications or Hz issues.



> I never got it running as reliably as I would like. I am currently giving it away on my YouTube channel.


Your "improvements" didn't work? A shame. I am shocked.

Send it to me, I'll "fix" it, demo that it works just fine, and send it back to you. Yes really. Or if I can't, I'll mail it at my cost to whoever you wanted to give it away to.



ballmatic said:


> Was the 50-60Mhz difference OK?


I'm not him, but I would be almost-almost-almost certain it's just fine.

His post count isn't high enough to accept PM's sadly, so you can't ask him directly.


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## Jimbo69ny (Feb 13, 2018)

Oops I was on my phone and read this quick. I thought this was my thread. My bad. Leave it to Matt to be there to throw shit in my face.


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## MattsAwesomeStuff (Aug 10, 2017)

Jimbo69ny said:


> Leave it to Matt to be there to throw shit in my face.


Offer to fix it for you for free and mail it to someone else at my personal cost if I can't.

But, you're the victim here, as always.


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## Jimbo69ny (Feb 13, 2018)

Far from a victim. I know you’ve said that to me multiple times now. I love my life and I’m definitely not a victim. You’re just a douche bag


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## MattsAwesomeStuff (Aug 10, 2017)

Jimbo69ny said:


> You’re just a douche bag


Again, I offered to fix it for free or mail it to someone of your choosing at my cost if I couldn't.

I'm in this thread helping two different people figure out if this machine will work for them, and, despite your refusal, tried to help you troubleshoot yours which you both claim you invented a solution, and complain it doesn't work at the same time. You claim you understand how it works but completely misinterpreted the actual solution you tried to copy from elsewhere and made the problem worse.

Meanwhile, a selection of quotes from you in this thread:

"I know you think you do everything right"
"Matt is always busting my balls telling me I am stupid. [...] he is just a drama queen."
"Matt is always condescending, thinks that he is always right and his way is the only way."
"Leave it to Matt to be there to throw shit in my face. "
"You’re just a douche bag"

... Your criticisms describe yourself, not me. I'm here helping people out, even you, despite your persistent psychosis and personal attacks. Worst I've done is poke a little fun at silliness.


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## Jimbo69ny (Feb 13, 2018)

I didn’t read your whole post. But again, I ask for nothing from you. Don’t need your opinions or help. Yet you love giving your opinion. This is my last post to you good bye. Have a nice life.


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## remy_martian (Feb 4, 2019)

No.


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## BVH (Jul 4, 2014)

If you are somewhat of a DIY person and are ok using RC Lipo batteries (or a very large lead acid battery, this spotwelder "kit" is fabulous. It is a big hit with the RC crowd on RCGroup Forums. I have one and absolutely love it. I had a Sunko and gave it away if that gives you any idea of a comparison of the two.






kWeld – complete kit | keenlab


kicksurfer.de | Innovative motion-sensing electric scooters.




www.keenlab.de





Here is a forum thread on the Kweld development and use with tons of user positive comments:



kWeld - "Next level" DIY battery spot welder - Endless Sphere



I linked page one but I'd start well beyond that point. Lots of posts.


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## Protoham (Oct 26, 2020)

power_aziz said:


> Hello all,
> 
> 
> I'm working on building a battery pack for a college EV project. I've been assembling it using 0.15 mm nickel strip between cells. The last spot welder I had (Sunkko 788H) died on me after I accidentally exceeded its duty cycle (which was never published).
> ...


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## Protoham (Oct 26, 2020)

I have the 709AD 220V version and it does not list Hz on the back. It did come with a 110V US plug which I cut off and changed over to a 220V plug. I have been running this thing on 220V 60Hz for several months and have built several batteries. The welds are excellent. I am using .2mm nickle. I am also running 12 pulses at 80% current. 

Don't even waste your time with the 110V versions, I am not sure how they can sell them with a straight face.


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