ElectricGod
10 MW
Darren2018 said:
You probably don't want to do that. If you have a super cap module, even if you turn off power to it, the caps are still charged.
kWeld - "Next level" DIY battery spot welder
- Thread starter tatus1969
- Start date
You probably don't want to do that. If you have a super cap module, even if you turn off power to it, the caps are still charged.
Darren2018
100 W
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- Aug 18, 2018
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- 223
ElectricGod said:
No that is exactly what I want to do, I use a high capacity lipo but I don't want to just leave it with the screen on. Do you guys just leave it on or disconnect the battery? I rack my electrodes after I have finished welding so I am not worried about the transistors and the fuse would break anyway. I am just not sure if there is a soft switch in the menu that I am missing. If there isn't can I just put a switch in series with the large capacitor on the left?
ElectricGod
10 MW
Darren2018 said:
OK...well if you are using the foot pedal, just unplug it. That will stop it from welding and it will just sit there powered.
Darren2018
100 W
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ElectricGod said:
I will measure the current used. Will the screen be ok powered up all the time?
Darren2018
100 W
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I welded 5 batteries with it in the last hour and I did around 4200 pulses at 10J which used 37Wh from a 2S 10Ah 130C graphene lipo. The electrodes didn't go past 45C with a rate of around 70 welds a minute, the lipo was around 30C, the 8AWG cables and terminals were around 35C, the mosfets were around 33C and the current averaged out to about 1070A. The ambient temp was 19C and I was using pure 0.15mm split nickel. The tips were in good condition after this short run and didn't need anything more than isopropyl to clean them up. This is a well made kit but I wish there was either a software switch or circuit breaker available, it would also be nice if the cables were closer together and at a 90 degree angle rather than being so far apart and low down.
ElectricGod
10 MW
Darren2018 said:
I'm wondering how good your welds are at 10 joules on .15mm nickel.
I need more like 40-50 joules to get solid welds in .15mm.
With such low power, it's not surprising your weld pens don't get hot.
I think you need to turn up the power a lot.
That many welds and my weld pens are getting pretty hot!
Darren2018
100 W
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I am using the tips supplied with the kit. The welds are good, I tested them by ripping off the nickel. The material, the split, current, pulse time and electrode shape are perfectly balanced which is why the welds have full penetration with low energy. When the tips wear I will just buy new ones because Keenlab cuts a perfect profile on them. If your welds leave craters and are burnt or there is not a hole in the nickel when it is removed then something in your formula is wrong.
This is bad
View attachment 1
This is good (minus the copper left behind which is accelerated electrode wear)
This is bad
View attachment 1
This is good (minus the copper left behind which is accelerated electrode wear)
In my opinion 40j is too much for 0.15mm nickel. 15-20j is about right for me but my nickel is just bare roll without thouse fancy cuts that probably make it just a little bit easier to weld.. And joule results can varry little bit depending battery and calibration. Important thing is that everyone can find setting that works and results are consistantElectricGod said:
You can put a switch between power supply and capacitor, current is much lower there depending on the rate of recharging. I don't recommend putting a high capacity / low ESR Lipo in parallel to the capacitors, because you'll likely exceed the welder's current limit by doing that. And you'd also need to charge the caps to the Lipo voltage before connecting them, or you'll have a very large (and possibly very loud and hot) current surge.Darren2018 said:
To make things worse, the new redesigned kCap module has a 70A current limit at its input, which will very likely blow from that surge. When connecting a battery in parallel to that, that must go to the output terminals. The kCap module is designed to be used with a current limited power supply, without the need of an additional Lipo. It supplies enough current for up to 0.2mm pure nickel by its own.
Just wanted to mention, there is nickel and there is nickel plated steel (Hilumin). The latter welds much easier because of the higher electrical resistance of steel. Many sellers try to sell Hilumin as pure nickel (guess where they are based); I use to test them with my Dremel with cutting disc - if it sparks then you know it's steel.ElectricGod said:
ElectricGod
10 MW
tatus1969 said:
That might explain the low joule level mentioned above.
I did the spark test too.
I also deeply scratched my strips and put it in salt water to be sure.
No sparks or rust...pretty sure mine is all nickel.
I get very poor weld strength at 10 joules with .15mm.
I have some Hilumin and at 50 joules it blows through.
Real nickel at 50 joules is solid.
70 joules can blow intermittent holes through the cell bottom.
I'm set to 1000 amps...I think. =)
What I really like is solder paste and the spot weld.
That's unstoppable!
ElectricGod
10 MW
tatus1969 said:
OK...what's the setting in the welder do?
There's a setting for amps in there.
ElectricGod
10 MW
flippy said:
Yes..
I use a 50 amp Meanwell PSU to keep my super caps charged.
I can weld faster than the PSU can charge the super caps.
As the super cap voltage drops off, I'll also notice that welds get less deep.
Both my super cap modules have an LED volt meter on them so I can glance over and see the voltage.
There is a minimum voltage where weld quality gets pretty poor.
Welding power drops quadratically with voltage, so every bit is important here. I set the undervoltage detection of kWeld to 7.9V and use it as a safeguard to not attempt making another pulse with partly discharged caps.flippy said:
Compoundbike
100 W
I have some problems with my K-Weld. It stopped making welds.. it sparks but the weld is not there.
I checked the battery, calibrated again and again.. however it doesnt weld, any known issues what i can look for ?
I checked the battery, calibrated again and again.. however it doesnt weld, any known issues what i can look for ?
ElectricGod
10 MW
tatus1969 said:
I set mine a bit lower...7.2v, but then weld quality was not very good and I went back to 7.9v.
7.5v was definitely not a great weld.
ElectricGod
10 MW
Compoundbike said:
sparking is usually an indication that the battery and the nickel are not conducting with each other very well.
You have crud on your cell or nickel that is keeping the weld from happening.
You might be able to press down harder and push through the crud.
I'd get some denatured alcohol and wipe off the surfaces before welding.
Silly question but has anyone made up their own supply pack for their kweld using 18650s?
Will likely use a ~65AH car battery most of the time but it would be great to use them for a more portable setup.
On another note, drew this electrode holder up for anyone that may find it useful, shaped to be easily held, one piece and no exposed metal
https://www.thingiverse.com/thing:4117601
Will likely use a ~65AH car battery most of the time but it would be great to use them for a more portable setup.
On another note, drew this electrode holder up for anyone that may find it useful, shaped to be easily held, one piece and no exposed metal
https://www.thingiverse.com/thing:4117601
