# Kweld spot welder

Lool. Or I’m dumb.

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Was more a exercise to compare the discharge to what we more use to I’m surprised of how much more puntch the newer lipos have in comparison the 40-50 cell lith ion packs we build

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The Red are 90c burst I never realised or seen any green at that only seen 150c burst I thort that was the difrance the green having a higher discharge than the red of 75c. Green over 45c Red

the super caps are used as a power supply from the mains as a alternative to using battery’s but a more price alternative

1000w PSU + 6 or more sup caps

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3s12p 25r bank, and it’s NOWHERE near fast enough for spot welding.

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Comparing the Green Turnigy Graphene Lipos applying the maths above to give people a starting point for useing them as the power source of a Kweld

6Ah 7mOhm Resistance

5Ah 9mOhm Resistance

4Ah 10mOhm Resistance

3Ah 13mOhm Resistances

2.2Ah 10mOhm Resistance (this look to low to me)
1.4Ah 13mOhm Resistance (this look to low to me)

KWeld Resitance 42mOhm or 0.0042ohm

To push the minimum of 800a
0.0042ohm*800A=3.36V

3s is 11.1-3.36=7.74
7.74V/800A=0.009675=9.7mOhm

so in Theory a 3S battery up to 9.7mOhm is bare minimum the closest is the Green 4Ah Turnigy Graphene at 10mOhm as the BARE MINIMUM.

Ideally it wants to push 1500A
0.0042ohm*1500A=6.3V
3s is 11.1V-6.3V=4.8V
4.8V/1500A=0.0032ohm (3.2mOhm)

Triple Turnigy 5ah in Parallel
(1/9)+(1/9)+(1/9)=0.333
1/0.333=3mOhm

Triple Turnigy 4Ah in Parallel
(1/10)+(1/10)+(1/10)=0.3
1/0.3=3.3mOhm

Dule Turnigy 6ah in Parallel
(1/7)+(1/7)=0.286
1/0.286=3.5mOhm

As the maths show in terms of Green Turnigy Graphene 4ah is the bare minimum 12Ah is preferred

What I can confirm in parties is single 3s6ah dose 1200-1400amps and dule 3s6Ah (3s12Ah) dose 1600-1800Amps

Hope fully you can follow this and it adds some evidence to why x or y is the one that should work for people to make up there own minds.

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Amazing! so the most cost effective choice for an optimal condition is dual 6h green graphene.
Are the one listed all green one? Maybe put a link or the full name next to it. It will help a lot to don’t get confused.
Thanks for the big input

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Done the work for you and added it in Previous post now. as fare as I’m aware the red have a higher internal resistance resulting in a lower discharge but I’m unable to fined the values currently just green are 75c constant 150c burst. Red are 45c constant and 90c burst. iv never personally used a Red Graphene.

If I was guessing I’d predict a 6Ah Red was about the min and 3*6Ah Red would be preferred Mathematically but that’s me guessing and it’s been proven the results in real are a little better in practise

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thanks a lot so all green graphene. Thanks for the work.

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im waiting till black friday. these defiently go on sale during black friday week. they will be like half the price.

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me too now that you mentioned

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I’ll chime in again and say a lot of people are using these happily with single lipos for welding up to .20mm nickel. Thicker nickel, and copper, seem to stress the system as a whole (cells get hot), and seems not worth pursuing. I don’t think getting more than 1 lipo pack makes good return on investment if you’re building packs for just yourself.

There is a path worth investigating though, sandwiching copper with nickel.

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I was going to say making the lipo investment might as well be a working esk8 Battery too.

So 4x 3S 3Ah For \$170 let’s call it \$140 sale price.
Use 2-3 for welding. All for esk8.

To be honest if I was only going to build 2-3 battery’s and I was set on the 3S3Ah battery’s because I would use them for some thing else. then I personally would buy only 2 it would work fine and if you build more than 2-3 you could expand the system later by adding more as i start getting faster welding after my 2nd built Battry.

I started with a 6Ah battery and I checked it a lot and was cutting Nickle in between welds and it only warmed up a little bit wasn’t until the 3rd I stoped a few times to let every thing cool down as as it was getting to warm for comfort because by then I got faster. IMO 1200amps is a good amount and I was getting that easily from a 6AH battry giving me 1400-1600 if I remember correctly. rember this is only my opinion you could be quicker and more never hurts untill you exceed the 2000a limit of the Kweld

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Just got my Kweld in the mail and assembled most of it tonight. I’m really interested in playing around with different tab materials.

Nickel’s cool and all, but has anyone tried welding nickel plated copper? I still need to find a source. IIRC the main problem with copper is it fuses to the electrodes more readily, but maybe a nickel coating would help. I’m quite unsure of the welding characteristics of these specific electrodes.

It should also be possible to use tungsten electrodes if you guys really want to get fancy with copper. Unfortunately the only copper spot welders I’ve seen also implement a shielding gas.

Anyways, why don’t lead acids get some love in this thread, I haven’t seen one during my gloss over. I was planning on using a fat one since it’s safer than lipos. Any particular issues with this?

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I haven’t seen that, how about you get a nickel plating kit, make some & be the guy for a week or so

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These results worry me a bit, not sure if Hobbyking is doing the right measurements for us. Most importantly the test frequency (ESR is a function of frequency). I did own measurements with my red 3S/6AH/65C Graphene that is no longer sold, and got significantly lower ESR than the 9mOhm of the Graphene Panther 3S/6AH/75C (that’s the closes match). I can’t find my notes but from memory it was somewhere at 4 to 5 mOhms. I trust my results as I am using a precision current shunt along with my 300MHz oscilloscope to record the current and voltages during actual welding pulse.

I should probably purchase one of the newer models and repeat my analysis. My preference would be that mentioned model, anyone having another suggestion? If you want to be on the safe side, my original recommendation is still available for purchase: https://hobbyking.com/en_us/turnigy-battery-nano-tech-5000mah-3s-65-130c-lipo-pack-xt-90.html

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Hmh, so I just got mine setup and running.

Went through the setup procedure. Looks like I scored a really low mR, 1.68.

If 2.2-3.0 is typical, are there any chances of complications from a lower value? Manual isn’t quite descriptive.

I was using one of these and it got hot quite quickly, two in parallel works beautifully

Which one? The forum seems to have deleted your referral.
EDIT: found the button. This one, right? " Turnigy Graphene Panther 4000mAh 3S 75C Battery Pack w/XT90" How many amperes do you get with one or two of them?

That’s a too low reading. The current probe design usually is at 2.1 milliOhms, Do you have the stock probe system with original cable lenghts (0.8m round trip on the output side)? The current measurement relies on good contact between the bus bars and the PCB, maybe you can try some cleaning (fine sand paper) of the bus bars. Also check that there are no burrs or other debris between them.