JP spot-welder, FET-switched, timed adj. pulse

Doctorbass said:
Q1: What's the best electrode material for spotwelding copper sheet?

i have about 10 sq ft of 99.99% pure 0.005" copper.. for using with that tool. i preffer copper over the nickel for my high current use.

I guess sthat copper probe with copper material is not the best idea... :lol:

I tought about tungsten probe?

My setup should have 2.6 farads of very low esr caps.. total should be less than 150microohms.

Q2: I also Wonder whats the best voltage to go... 12V seem the rule now.. but increasing volt a bit crank up the joules alot! so.. i guess the max volt the Jp spotwelder can do is 16V according to the caps as i've read?

Thanks all for answer Q1 and Q2. :)

Doc
Click to expand...


1.) dont do it
2.) you can experiment. 12v would be a good starting point.
You can go all the way to ~24V. The fets will last longer using caps and can handle higher voltage because the current will taper to zero by the time the pulse finishes, thus the current will be very slow at mosfet turn off (which is when they are damaged). The downside of caps is the current is not continuous or smooth, inferior welding performance due to the high current peak at start
 
okashira said:
Doctorbass said:
Q1: What's the best electrode material for spotwelding copper sheet?

i have about 10 sq ft of 99.99% pure 0.005" copper.. for using with that tool. i preffer copper over the nickel for my high current use.

I guess sthat copper probe with copper material is not the best idea... :lol:

I tought about tungsten probe?

My setup should have 2.6 farads of very low esr caps.. total should be less than 150microohms.

Q2: I also Wonder whats the best voltage to go... 12V seem the rule now.. but increasing volt a bit crank up the joules alot! so.. i guess the max volt the Jp spotwelder can do is 16V according to the caps as i've read?

Thanks all for answer Q1 and Q2. :)

Doc
Click to expand...


1.) dont do it
Click to expand...


........ :| so why?... You should know already that i usually expect to get the reason in the answer :wink:

Doc
 
Doctorbass said:
okashira said:
Doctorbass said:
Q1: What's the best electrode material for spotwelding copper sheet?

i have about 10 sq ft of 99.99% pure 0.005" copper.. for using with that tool. i preffer copper over the nickel for my high current use.

I guess sthat copper probe with copper material is not the best idea... :lol:

I tought about tungsten probe?

My setup should have 2.6 farads of very low esr caps.. total should be less than 150microohms.

Q2: I also Wonder whats the best voltage to go... 12V seem the rule now.. but increasing volt a bit crank up the joules alot! so.. i guess the max volt the Jp spotwelder can do is 16V according to the caps as i've read?

Thanks all for answer Q1 and Q2. :)

Doc
Click to expand...


1.) dont do it
Click to expand...


........ :| so why?... You should know already that i usually expect to get the reason in the answer :wink:

Doc
Click to expand...
Welds suck, not reliable poor mechanical strength
 
okashira said:
With my battery, I can guarantee welder (mosfet) durability, and welding performance
Not sure why you guys are against the battery. They are great cells you can re-purpose in the future and they will last many years. They are rated for 20,000 cycles plus
For international folks, contact me directly so we can do it without a battery
Click to expand...

If mine dies, I will want a replacement capable of being used with lead acid. Not because it's better in any shape or form, just lower on shipping, will use existing batteries and replacements are cheaply available. However, if the shipping was cheap enough, I'd consider replacing with your battery inclusive option. Nothing better than a one stop shop and being able to use it straight away. A neat case to keep it in would also be ideal and could serve as shipping packaging. And yes, I would be willing to pay more for one.

I'd also be interested in purchasing 'screwable' within pack cell holder spacers (see most recent Snath pack), BMS wire, cell holders, nickel strip and heatshrink in a 'just get the freakin battery done' upgrade pack or as a stand alone order. Its awesome to get all the bits together, getting it together and going for a ride!! 8) Food for thought anyway.
 
That is very interesting. My take was that capacitor discharge welder so were the tits when it came to welding for superior repeatable welds. That was the reason I built one. I don't have enough knowledge nor experience to debate it but online research I believe would differ seeing how 99% of the (let's call the professional machines) battery tab welder are CD?

Very interested in your views.

My welder is a V2.5 800Ws CD welder capable of about 10k amps and voltage adjustable from 1 volt all the way to 23.2 volts running 3-1 Farad computer grade capacitors and a bank of 18 power mosfets.

Link to what I built....http://frikkieg.blogspot.com

Tom
 
litespeed said:
That is very interesting. My take was that capacitor discharge welder so were the tits when it came to welding for superior repeatable welds. That was the reason I built one. I don't have enough knowledge nor experience to debate it but online research I believe would differ seeing how 99% of the (let's call the professional machines) battery tab welder are CD?

Very interested in your views.

My welder is a V2.5 800Ws CD welder capable of about 10k amps and voltage adjustable from 1 volt all the way to 23.2 volts running 3-1 Farad computer grade capacitors and a bank of 18 power mosfets.

Link to what I built....http://frikkieg.blogspot.com

Tom
Click to expand...

[strike]Tom, I emailed you a month or two ago about this and mentioned this. I was interested in your pulse arc welder (and still am).
Anyway, email me back with any questions.[/strike]

Oops, read wrong, I thought you were the guy who designed that spot welder! :)

Like I said above, batteries ideal for welding due to the constant current. Capacitors - they deliver a high peak current, that tapers off until mosfet turn off.
This is less ideal for welding (IMHO) but it helps mosfet durability because the fets will turn off at a lower current.
However I've found we can fix that problem with a flyback circuit and voltage suppression diodes.

I think that sunstone, and the other pulse welder suppliers use capacitors for obvious reasons (supply, cost, safety, design complexity), not because they are superior for the actual welding process
 
litespeed said:
That is very interesting. My take was that capacitor discharge welder so were the tits when it came to welding for superior repeatable welds. That was the reason I built one. I don't have enough knowledge nor experience to debate it but online research I believe would differ seeing how 99% of the (let's call the professional machines) battery tab welder are CD?

Very interested in your views.

My welder is a V2.5 800Ws CD welder capable of about 10k amps and voltage adjustable from 1 volt all the way to 23.2 volts running 3-1 Farad computer grade capacitors and a bank of 18 power mosfets.

Link to what I built....http://frikkieg.blogspot.com

Tom
Click to expand...


Hi, remember back when we had a debate, and I've posted some graphs on how CD spot welders have ugly, triangle like pulse? Now you can compare that to perfect square pulses from battery welders we measured and posted on this thread. You didn't believe me back that, and I've said I'm gonna prove it, so there you go :p
 
riba2233 said:
litespeed said:
That is very interesting. My take was that capacitor discharge welder so were the tits when it came to welding for superior repeatable welds. That was the reason I built one. I don't have enough knowledge nor experience to debate it but online research I believe would differ seeing how 99% of the (let's call the professional machines) battery tab welder are CD?

Very interested in your views.

My welder is a V2.5 800Ws CD welder capable of about 10k amps and voltage adjustable from 1 volt all the way to 23.2 volts running 3-1 Farad computer grade capacitors and a bank of 18 power mosfets.

Link to what I built....http://frikkieg.blogspot.com

Tom
Click to expand...


Hi, remember back when we had a debate, and I've posted some graphs on how CD spot welders have ugly, triangle like pulse? Now you can compare that to perfect square pulses from battery welders we measured and posted on this thread. You didn't believe me back that, and I've said I'm gonna prove it, so there you go :p
Click to expand...


Yep, you need around 2,000 amps to weld 0.2mm nickel.
With reasonable length weld leads, it takes ~0.8ms to ramp to 2000 amps. Then you need another 7ms or so at 2000 amps to complete the weld. By that time, the caps will have discharged significantly so the current will drop.
you can run a large cap array, but then the cost goes up.
Or run a higher voltage on the caps, but then your initial current ramps too high. messing up the weld.

So in terms of cost/performance, even lead acid wins, but modern lithium ion is even better these days.
 
riba2233 said:
litespeed said:
That is very interesting. My take was that capacitor discharge welder so were the tits when it came to welding for superior repeatable welds. That was the reason I built one. I don't have enough knowledge nor experience to debate it but online research I believe would differ seeing how 99% of the (let's call the professional machines) battery tab welder are CD?

Very interested in your views.

My welder is a V2.5 800Ws CD welder capable of about 10k amps and voltage adjustable from 1 volt all the way to 23.2 volts running 3-1 Farad computer grade capacitors and a bank of 18 power mosfets.

Link to what I built....http://frikkieg.blogspot.com

Tom
Click to expand...


Hi, remember back when we had a debate, and I've posted some graphs on how CD spot welders have ugly, triangle like pulse? Now you can compare that to perfect square pulses from battery welders we measured and posted on this thread. You didn't believe me back that, and I've said I'm gonna prove it, so there you go :p
Click to expand...

I didn't actually see the "proof" just one side. Where is the pulse from a good properly designed CD welder? If it's better then it's better....but just not by saying so. I have my welder and you have yours so as far as that goes they both do as intended, Mine works perfect and will weld .3 mm as well. One day if I feel up to it I'll try copper and other metals....with all the adjustability of mine I would have to think it could be more diverse or could be more fine tuned for precision welding.

Interesting that the rest of the world with all the engineers out there that no one else has thought of this from a battery building concept. I feel bad for all those that bought 4 to 10 thousand dollar CD welders and could have just pulled the battery out of their car..... Cudos for that idea.

Tom
 
litespeed said:
riba2233 said:
litespeed said:
That is very interesting. My take was that capacitor discharge welder so were the tits when it came to welding for superior repeatable welds. That was the reason I built one. I don't have enough knowledge nor experience to debate it but online research I believe would differ seeing how 99% of the (let's call the professional machines) battery tab welder are CD?

Very interested in your views.

My welder is a V2.5 800Ws CD welder capable of about 10k amps and voltage adjustable from 1 volt all the way to 23.2 volts running 3-1 Farad computer grade capacitors and a bank of 18 power mosfets.

Link to what I built....http://frikkieg.blogspot.com

Tom
Click to expand...


Hi, remember back when we had a debate, and I've posted some graphs on how CD spot welders have ugly, triangle like pulse? Now you can compare that to perfect square pulses from battery welders we measured and posted on this thread. You didn't believe me back that, and I've said I'm gonna prove it, so there you go :p
Click to expand...

I didn't actually see the "proof" just one side. Where is the pulse from a good properly designed CD welder? If it's better then it's better....but just not by saying so. I have my welder and you have yours so as far as that goes they both do as intended, Mine works perfect and will weld .3 mm as well. One day if I feel up to it I'll try copper and other metals....with all the adjustability of mine I would have to think it could be more diverse or could be more fine tuned for precision welding.

Interesting that the rest of the world with all the engineers out there that no one else has thought of this from a battery building concept. I feel bad for all those that bought 4 to 10 thousand dollar CD welders and could have just pulled the battery out of their car..... Cudos for that idea.

Tom
Click to expand...

you are kidding right? People have been using 12v - 24v lead acid and coat hangers to spot tack weld for decades
I already explained why the commercial welders use CD not batteries

Fritz's welder is great, but JP's does just as well for much cheaper / smaller
 
Actually you did not, you just said, "I think that sunstone, and the other pulse welder suppliers use capacitors for obvious reasons (supply, cost, safety, design complexity), not because they are superior for the actual welding process" not necessarily an explanation more of a guess. I would respectfully disagree with that statement in almost every way.

Actually prior to the JP welder and with my online research before building my welder looked for months trying to find a good spot welder. Never once did I see a battery welder besides at JC Whitney for body work and a high dollar off road arc welder that ran off a couple batteries. I would have totally bought one had it showed up prior to me building one.

Can't imagine a battery and a coat hanger........

Definitely not kidding just fascinated by this welding stuff. I can stick weld, Heli arc, mig, acc/oxy weld and a little tig also actually certified in stick so I know welding. At 50 I've been around the block and I'm from the Show-Me state so things just don't go over with "I said it!' It wasn't meant to be an arguement just a discussion since this is after all, a discussion board.

Have a great day.

Tom
 
litespeed said:
Actually you did not, you just said, "I think that sunstone, and the other pulse welder suppliers use capacitors for obvious reasons (supply, cost, safety, design complexity), not because they are superior for the actual welding process" not necessarily an explanation more of a guess. I would respectfully disagree with that statement in almost every way.

Actually prior to the JP welder and with my online research before building my welder looked for months trying to find a good spot welder. Never once did I see a battery welder besides at JC Whitney for body work and a high dollar off road arc welder that ran off a couple batteries. I would have totally bought one had it showed up prior to me building one.

Can't imagine a battery and a coat hanger........

Definitely not kidding just fascinated by this welding stuff. I can stick weld, Heli arc, mig, acc/oxy weld and a little tig also actually certified in stick so I know welding. At 50 I've been around the block and I'm from the Show-Me state so things just don't go over with "I said it!' It wasn't meant to be an arguement just a discussion since this is after all, a discussion board.

Have a great day.

Tom
Click to expand...

I don't do welding myself, but I have written weld specifications and advised welders and weld vendors on: laser welding cobalt and tungsten alloys - robotic tig welding of inconel, electron beam welding of cobalt and nickel alloys to carbon steels, as well as heat treatment of complex welded alloy combinations to meet NACE, etc.
An off road welder powered by a battery is not high dollar :) A million dollar laser welding system is
I also have 8 years experience in actual product development.
There are so many reasons a company like Sunstone have not put a battery in their welder. Not going to write a college research paper to explain it to you. The proof is there.
That said, I think eventually you will find Sunstone will put a battery in one of there products with the recent advancements of lithium ion and BMS technology. :)
Let me add this: One CAN make caps perform just as well as a battery for spot welding, with good control design, but in the end it will be more expensive then a battery solution. And now, a lithium ion solution will also be smaller and lighter. :)
 
Guys, Calm down.... :)

Its this simple.

For diy its easier to use a battery. But you need to use lead which is expensive to ship or a Lithium battery which needs a BMS and charger which is expensive to design. But many DIY projects people cut corners on the BMS end or they pic up a lead battery locally.

For a professional welder you will see they use Caps because caps can release and store energy much faster and repeat the process many more times then a battery. But also its cheaper and safer to sell something with caps them something with lead or lithium.
 
Arlo1 said:
Guys, Calm down.... :)

Its this simple.

For diy its easier to use a battery. But you need to use lead which is expensive to ship or a Lithium battery which needs a BMS and charger which is expensive to design. But many DIY projects people cut corners on the BMS end or they pic up a lead battery locally.

For a professional welder you will see they use Caps because caps can release and store energy much faster and repeat the process many more times then a battery. But also its cheaper and safer to sell something with caps them something with lead or lithium.
Click to expand...

8)
 
Alan B said:
If we could get good caps cheap and easy that would be one thing. But it isn't that cheap or that easy to get good caps.

Great to have choices. :)
Click to expand...
Its not that expensive.

I think with $200-$300 you could get some poly caps combined with a big electrolytic or two.

https://www.digikey.ca/product-detail/en/united-chemi-con/E36D500LPN104TEA5M/565-3323-ND/2095937

Digikey# 565-3323-ND

What you do is bring the voltage up to ~ 30v and then use a decent power supply to keep the caps charged.
 
Alan B said:
Going higher in voltage causes a number of problems, and that's still a $200 solution instead of a $50 solution. I think the lower voltage is a requirement, and more capacitance is needed. I have a couple of 1F caps that will probably work, but buying them new is difficult and very costly.
Click to expand...
What is the $50 2000+ amp battery you speak of?
 
Alan B said:
A refurbished or used car starting battery. Even a brand new one is only $100.
Click to expand...
Where I live its over $200 for something decent.
But....
Ok but if comparing NEW to NEW quality to quality the cost of caps VS batteries is not far apart.

And I only suggested upping the voltage as a trick to get the current high enough before the caps are empty.
 
Increasing the voltage makes the initial current higher than desired, it is a nontrivial problem.

If you have caps or want caps, go with the cap welder designs. They use a lot more FETs, slightly higher voltages and different timing. The designs are slightly different. If you go with a battery then these designs are applicable. There are many, many examples of cap based designs out there. Not so many battery based designs.
 
Finally. Did a before and after fully quantifying the effect of the flyback diode. Further, Added a TVS diode and I was able to completely prevent avalanche!


SOURCE-DRAIN VOLTAGE @ MOSFET TURN OFF
All are done at welding current of about 2,500 amps.
1.) WHITE - no diode - 110 microseconds of avalanche, peak voltage of 30.5V across FET's
2.) ORANGE - flyback diode added - 20 microseconds of avalanche, peak voltage of 29V across FET's
3.) YELLOW - TVS diode added - zero avalanche - peak voltage of ~21V
tEDxoJE.jpg


One way I really found out that the flyback is doing most of the work. I tried the TVS diode alone, and it immediatly blew the leg of the TVS diode on the first pulse. It's fine with the flyback there.
s20i9WK.jpg





TEST SETUP
cfaUH4t.jpg
 
Went to 9.4V to use full battery. Also decided to push it a bit more by bypass one lead all together and shorting the left lead straight to the battery :twisted: :twisted:

Result, 2.16V across 27" of 4awg wire over full 20ms pulse (full power) - that is 3,863 amps. And no avalanche! Mosfets did not even get warm after a few repeated pulses.
I4OjTYR.jpg
 
Tom[/quote]
you are kidding right? People have been using 12v - 24v lead acid and coat hangers to spot tack weld for decades
[/quote]

Wow. Lol. Please show me an example of this. Last time i checked coat hangers are made of steel, which is 10x worse conductor compared to copper.
 
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