18650 spot welding -how to- ULTIMATE REPOSITORY

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by tomjasz » Apr 10 2017 1:33am

I saw an overpriced probe set. Two probes set up close into a single handle. Has anyone worked out a homebuilt solution?

Called a welding pen...$50

Anyone have a solution?
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DVDRW » Apr 10 2017 10:55am

Didn't understand price either.
Gave up and just soldered wires directly to transformer output. Two hand operation but works perfectly.
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by jmz » Apr 16 2017 12:28am

Crossposting from my build thread to ask some pack assembly advice:

I am still at the point of having 20 out of 22 9p sub-packs constructed (see: https://imgur.com/a/gsK9c), I have the materials to finish the rest after ordering some replacement HG2 to replace the ones I blew up during my iterative welding/welder-development process.

I have also acquired a whole lot of 0.3mm flat nickel sheet, which I have cut into trapezoidal shapes to make a single series connection between two 9p packs.

I have found at the voltage levels that I previously recorded the welder having acceptable voltage overshoot (22-23V, 1.2-ish Farads), making test welds between 0.3mm nickel plates was not giving good weld adherence.

This is with a weld profile that I adopted designed to minimise arcing/exploding with capacitive discharge, over variation in surface conductivity: 500us (on), 1ms (off), 500us (on), 1ms (off), 8ms on. This profile has worked well at the power levels I have needed for 0.3mm nickel-to-cell-tab (nickel-plated steel, which seems to have a markedly different characteristic to pure nickel-nickel welds).

I think I have two options:

1) Modify my CD welder to have freewheeling diodes *as well as* the existing drain-source capacitive snubbers, which should make it robust enough to significantly increase the weld voltage and current, and so achieve direct 0.3mm nickel-nickel welding.

2) Using my pre-cut nickel plate, make the series connections using solder. This seems viable, as the cells now have nickel parallel buses attached, which could provide enough thermal mass and isolation to avoid overly heating the cells. It might be possible to use things like freeze-spray also and good surface prep to minimise heating.

Thoughts? I really need to get my act together and finish this thing huh.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by vex_zg » Apr 16 2017 3:43am

jmz wrote:Crossposting from my build thread to ask some pack assembly advice:

I am still at the point of having 20 out of 22 9p sub-packs constructed (see: https://imgur.com/a/gsK9c), I have the materials to finish the rest after ordering some replacement HG2 to replace the ones I blew up during my iterative welding/welder-development process.

I have also acquired a whole lot of 0.3mm flat nickel sheet, which I have cut into trapezoidal shapes to make a single series connection between two 9p packs.

I have found at the voltage levels that I previously recorded the welder having acceptable voltage overshoot (22-23V, 1.2-ish Farads), making test welds between 0.3mm nickel plates was not giving good weld adherence.

This is with a weld profile that I adopted designed to minimise arcing/exploding with capacitive discharge, over variation in surface conductivity: 500us (on), 1ms (off), 500us (on), 1ms (off), 8ms on. This profile has worked well at the power levels I have needed for 0.3mm nickel-to-cell-tab (nickel-plated steel, which seems to have a markedly different characteristic to pure nickel-nickel welds).

I think I have two options:

1) Modify my CD welder to have freewheeling diodes *as well as* the existing drain-source capacitive snubbers, which should make it robust enough to significantly increase the weld voltage and current, and so achieve direct 0.3mm nickel-nickel welding.

2) Using my pre-cut nickel plate, make the series connections using solder. This seems viable, as the cells now have nickel parallel buses attached, which could provide enough thermal mass and isolation to avoid overly heating the cells. It might be possible to use things like freeze-spray also and good surface prep to minimise heating.

Thoughts? I really need to get my act together and finish this thing huh.
I experimented a lot with my 2F welder and .1mm copper & .3mm nickel tabs. I only used 2 pulses, was considering spreading the energy over more pulses to reduce chances of blowout.

I added discharge energy calculation to my welder to be able to fine tune welding energy that was spent.

The issue is that energies required to securely weld 0.3mm nickel are overlaping with the energy needed to cause a blowout, and short circuit within the battery (had it once - battery had an internal short and overheated in 5 seconds. Fortunately was an empty old cell). So even when I really fine tuned the energy level - still occasionally there would be a blowout. If you multiply even a 1% of a blowout with some 600welds needed for 100 cells welding the probability is quite high.

If you really wanted to pursue the .3mm nickel path I would use slotted .3mm with long slots or even completely slotted strip - meaning cutting it in half longitudinaly, to reduce needed weld energy. This tactic helped a lot with copper. Also using higher capacity but with lower voltage helped reduce chance of blowout.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 16 2017 2:11pm

[spoiler=quote="DVDRW"]
DVDRW wrote:Didn't understand price either.
Gave up and just soldered wires directly to transformer output. Two hand operation but works perfectly.
Image
[/spoiler]

Could you not just put these cables to there where these summits are? Then you wouldnt have to open the whole thing.
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DVDRW » Apr 17 2017 11:51am

788 Welding voltage is very low ~3V AC. Inch or more longer cable and welding performance decreases dramatically.
Been there done that, see holes on front.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by flippy » Apr 18 2017 7:20am

can you show a picture of how you made the connection? of did you just replace the wire in the transformer?
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DVDRW » Apr 19 2017 11:07am

Just soldered to transformer wire.
http://i.imgur.com/QjQFjij.jpg

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by vex_zg » Apr 19 2017 3:39pm

DVDRW wrote:Just soldered to transformer wire.
http://i.imgur.com/QjQFjij.jpg
the transformer is still triggered/turned on by the original control electronics of the welder?

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 20 2017 3:44am

I still dont get it. Why soldering the AWG wires inside, when you also could put them outside, where the original nipples of the welder are???

PS: What AWG wires are these? 12AWG? 10AWG? 8AWG?
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by vex_zg » Apr 20 2017 4:23am

DasDouble wrote:I still dont get it. Why soldering the AWG wires inside, when you also could put them outside, where the original nipples of the welder are???

PS: What AWG wires are these? 12AWG? 10AWG? 8AWG?
the new wires are much bigger and lower resistance so by soldering them directly to the output of transformer you bypass some of the thinner higher resistance wires inside.

every miliohm matters at these high currents. 1 miliohm causes voltage drop of 1V at 1000A. If you have only 3V to start with this matters quite a lot.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DVDRW » Apr 20 2017 4:52am

Jep, resistance is critical.
Dont know AWG exactly. Found about 0 or 1AWG silicone wire lying around.

How these overpriced quite long extension probes work? 709A welder has higher voltage?

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by flippy » Apr 20 2017 8:45am

709 is identical as far as i can tell. and with the external leads (wich get effing hot!) it is impossible to weld even .3 strips.
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 22 2017 10:45am

Could someone please tell me what temperature acceptable and poor/hot means in °C? :?:

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 24 2017 5:26pm

DVDRW wrote:Didn't understand price either.
Gave up and just soldered wires directly to transformer output. Two hand operation but works perfectly.
Image
Will a 10 awg wire be enough for this modification?
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by flippy » Apr 25 2017 3:12am

never, you will burn those out in 10 minutes. 4 AWG would be minimum IMHO.
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by vex_zg » Apr 25 2017 7:59am

flippy wrote:never, you will burn those out in 10 minutes. 4 AWG would be minimum IMHO.
I am using AWG 1/0, AWG 2/0 was too big and heavy, but 1/0 is OK.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 25 2017 5:40pm

Could I theoretically use 3 times 10awg wires and combine them to one? Because I won´t get a 1/0 wire at the moment that fast. :pancake:
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by parabellum » Apr 25 2017 6:00pm

DasDouble wrote:Could I theoretically use 3 times 10awg wires and combine them to one? Because I won´t get a 1/0 wire at the moment that fast. :pancake:
Is there any hardware shop with welding supply near you? They will have flexible, rubber coated, arc welding wire, it comes in number of monstrous gauges and is not expensive.
You definitively can get enough parallel 10awg wires to conduct same current as 1/0 wire, but I do not know how they handle inductance in this case.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by vex_zg » Apr 26 2017 4:28pm

parabellum wrote:
DasDouble wrote:Could I theoretically use 3 times 10awg wires and combine them to one? Because I won´t get a 1/0 wire at the moment that fast. :pancake:
Is there any hardware shop with welding supply near you? They will have flexible, rubber coated, arc welding wire, it comes in number of monstrous gauges and is not expensive.
You definitively can get enough parallel 10awg wires to conduct same current as 1/0 wire, but I do not know how they handle inductance in this case.
inductance will be less when paralleled. But capacitance will be higher. Should not be an issue though.

If you are in a hurry you can use car jumper cables. You can get them very cheap in local big supermarket stores, they will most likely be CCA (copper clad aluminum) but should work. Worked for me when I was starting this project.

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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 26 2017 4:43pm

vex_zg wrote:
parabellum wrote:
DasDouble wrote:Could I theoretically use 3 times 10awg wires and combine them to one? Because I won´t get a 1/0 wire at the moment that fast. :pancake:
Is there any hardware shop with welding supply near you? They will have flexible, rubber coated, arc welding wire, it comes in number of monstrous gauges and is not expensive.
You definitively can get enough parallel 10awg wires to conduct same current as 1/0 wire, but I do not know how they handle inductance in this case.
inductance will be less when paralleled. But capacitance will be higher. Should not be an issue though.

If you are in a hurry you can use car jumper cables. You can get them very cheap in local big supermarket stores, they will most likely be CCA (copper clad aluminum) but should work. Worked for me when I was starting this project.
Hey, thats a great idea!!! Thanks! :)
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 27 2017 1:58pm

I have just got a 2/0 AWG wire for free. 1 meter :D :D :D Yey, let the weld beginn!
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DasDouble » Apr 29 2017 9:39am

DVDRW wrote:Didn't understand price either.
Gave up and just soldered wires directly to transformer output. Two hand operation but works perfectly.
Image
[/spoiler]
[/quote]

I have now just done the same modification like you DVDRW, but with 2/0 AWG. Well. Took me about 2-3 houres because the wires took a day and two to get warm enough for soldering :D. This will make things way easyer :mrgreen:
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by tomjasz » Apr 29 2017 11:17am

Has anyone built this welder with an Arduino timer? Also a display option?
http://www.avdweb.nl/tech-tips/spot-welder.html
http://www.avdweb.nl/arduino/hardware-i ... oller.html

click to enlarge.
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Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by vex_zg » Apr 29 2017 3:42pm

tomjasz wrote:Has anyone built this welder with an Arduino timer? Also a display option?
http://www.avdweb.nl/tech-tips/spot-welder.html
http://www.avdweb.nl/arduino/hardware-i ... oller.html

click to enlarge.
I started with something like that as goal but ended up building a 600ws 3F/20V CD welder myself, arduino controlled and configurable. I wanted something to weld .2mm copper and .3mm nickel, powerful reliable and customizable. Could not exactly find it so built it myself. Spent hundreds of hours, bought oscilloscope and learned a lot about transients, mosfets, arduino, and welding. Really happy with the result but I seriously overdid it :)

what do you want to weld? what thickness? how often do you want to weld? what's your skill level in mechanics, electronics and software development (arduino/c) ?

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