kWeld - "Next level" DIY battery spot welder

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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 15 2020 8:53pm

Darren2018 wrote:
Jan 15 2020 8:49pm
If there isn't one can I put a switch in series with the capacitor?
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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by Darren2018 » Jan 15 2020 9:12pm

ElectricGod wrote:
Jan 15 2020 8:53pm
Darren2018 wrote:
Jan 15 2020 8:49pm
If there isn't one can I put a switch in series with the capacitor?
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.
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?

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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 16 2020 12:14am

Darren2018 wrote:
Jan 15 2020 9:12pm
ElectricGod wrote:
Jan 15 2020 8:53pm
Darren2018 wrote:
Jan 15 2020 8:49pm
If there isn't one can I put a switch in series with the capacitor?
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.
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?
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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by Darren2018 » Jan 16 2020 1:04am

ElectricGod wrote:
Jan 16 2020 12:14am
Darren2018 wrote:
Jan 15 2020 9:12pm
ElectricGod wrote:
Jan 15 2020 8:53pm
Darren2018 wrote:
Jan 15 2020 8:49pm
If there isn't one can I put a switch in series with the capacitor?
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.
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?
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.
I will measure the current used. Will the screen be ok powered up all the time?

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Re: kWeld - "Next level" DIY battery spot welder

Post by Darren2018 » Jan 16 2020 1:36am

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.

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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 16 2020 1:56am

Darren2018 wrote:
Jan 16 2020 1:36am
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.
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!
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Re: kWeld - "Next level" DIY battery spot welder

Post by Darren2018 » Jan 16 2020 2:54am

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
IMG_3418 2 copy.JPG
IMG_3418 2 copy.JPG (179.15 KiB) Viewed 1606 times
This is good (minus the copper left behind which is accelerated electrode wear)
IMG_3592 copy.JPG
IMG_3592 copy.JPG (150.52 KiB) Viewed 1606 times

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Re: kWeld - "Next level" DIY battery spot welder

Post by ossivirt » Jan 16 2020 4:12am

ElectricGod wrote:
Jan 16 2020 1:56am
Darren2018 wrote:
Jan 16 2020 1:36am
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.
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!
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 consistant :)

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Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jan 16 2020 4:48am

Darren2018 wrote:
Jan 15 2020 8:49pm
If there isn't one can I put a switch in series with the capacitor?
You mean, between capacitor and welder? If you have a switch that is capable of carrying 2000A of current, then yes. Expect this to be hugely sized and priced :-)
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Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jan 16 2020 4:49am

ElectricGod wrote:
Jan 15 2020 12:07am
Maybe the pics for the new super cap module are not up yet?
It looks like the ones I already have.
Haven't had time to shoot new pics, but that is on my todo list!
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Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jan 16 2020 4:56am

Darren2018 wrote:
Jan 15 2020 9:12pm
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?
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.

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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jan 16 2020 5:01am

ElectricGod wrote:
Jan 16 2020 1:56am
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.
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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Jan 16 2020 12:53pm

i would love to see someone put a manual switch on a kcap. :lol:
tatus1969 wrote:
Jan 16 2020 5:01am
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.
i usually just take a piece and sand it down a bit and drop it in extremely salt water for 24h, any rust and you know you got shafted.
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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 16 2020 6:41pm

tatus1969 wrote:
Jan 16 2020 5:01am
ElectricGod wrote:
Jan 16 2020 1:56am
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.
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.
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!
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Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jan 17 2020 6:56am

ElectricGod wrote:
Jan 16 2020 6:41pm
I'm set to 1000 amps...I think. =)
That can't be adjusted, it's always the short circuit current that just happens. To check the actual reading, keep the foot pedal down after a weld.
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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 18 2020 8:16pm

tatus1969 wrote:
Jan 17 2020 6:56am
ElectricGod wrote:
Jan 16 2020 6:41pm
I'm set to 1000 amps...I think. =)
That can't be adjusted, it's always the short circuit current that just happens. To check the actual reading, keep the foot pedal down after a weld.
OK...what's the setting in the welder do?
There's a setting for amps in there.
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Re: kWeld - "Next level" DIY battery spot welder

Post by ossivirt » Jan 18 2020 8:25pm

ElectricGod wrote:
Jan 18 2020 8:16pm
tatus1969 wrote:
Jan 17 2020 6:56am
ElectricGod wrote:
Jan 16 2020 6:41pm
I'm set to 1000 amps...I think. =)
That can't be adjusted, it's always the short circuit current that just happens. To check the actual reading, keep the foot pedal down after a weld.
OK...what's the setting in the welder do?
There's a setting for amps in there.
Welder has setting to abort weldingpulse if the current dont reach set value. This usually means that contact is poor and without this cutoff it would just make arc untill max pulsetime is reached..(and likely burn holes)

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Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Jan 19 2020 3:23am

i wonder, has anyone tested that uses a kcap noticed how low they can go on the voltage before noticing a drop in weld quality?
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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 19 2020 11:25am

flippy wrote:
Jan 19 2020 3:23am
i wonder, has anyone tested that uses a kcap noticed how low they can go on the voltage before noticing a drop in weld quality?
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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Jan 19 2020 2:21pm

ElectricGod wrote:
Jan 19 2020 11:25am
There is a minimum voltage where weld quality gets pretty poor.
i start noticing a reduction at 7.5V, do you experience the same?
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Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jan 20 2020 5:40am

flippy wrote:
Jan 19 2020 2:21pm
ElectricGod wrote:
Jan 19 2020 11:25am
There is a minimum voltage where weld quality gets pretty poor.
i start noticing a reduction at 7.5V, do you experience the same?
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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by Compoundbike » Jan 20 2020 2:13pm

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 ?

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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 20 2020 9:14pm

tatus1969 wrote:
Jan 20 2020 5:40am
flippy wrote:
Jan 19 2020 2:21pm
ElectricGod wrote:
Jan 19 2020 11:25am
There is a minimum voltage where weld quality gets pretty poor.
i start noticing a reduction at 7.5V, do you experience the same?
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.
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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by ElectricGod » Jan 20 2020 9:16pm

Compoundbike wrote:
Jan 20 2020 2:13pm
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 ?
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.
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Re: kWeld - "Next level" DIY battery spot welder

Post by Qachi » Jan 21 2020 3:02am

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

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