kWeld - "Next level" DIY battery spot welder
- Thread starter tatus1969
- Start date
julian.koenig87
1 µW
Ohhh... Now I see. Did not realise that this is an alloy! So yeah. I will go with 0.1 copper foil an 0.15 nickel on top.
Because I have also nickel/steel laying around. How critical is nickel/steel for tool battery packs (sealed) used indoors and outdoor only in dry conditions? Never heard of such relevant problems you stated.
if you keep them dry, and not in a super humid environment it wont be detrimental, probably a couple years before you see any rust, but you would be surprised how fast they can rust with humidity. i suppose its not that big of a deal when you are doing copper under them, as they are essentially just there to hold the copper in place. however, welding them is not very fun because they will shoot out a ton of sparks at every weld vs nickel with almost none.
nickel is fairly cheap, and you dont need a whole lot, i usually just cut out little buttons (like a 10mmx10mm piece) of it that go on top the copper to weld, since it the copper is what carries the current. a 2 meter strip is enough for about 100 cells
julian.koenig87
1 µW
Hi. I recieved the kweld. Nice tool!
I changed the inputconnection to (in germany quite common) 2x10mm tinned copper an soldered 3 XT90 plugs to it. Now I can decide wether I weld with 2 or 3 lipos. Pictures attached with one 3S 5Ah 65-130C HK Lipo and one old 3S 4Ah 60C good quality lipo.
Calibrating at (3,85V) 1750A. So good range. Can go higher if I needed.
Pictures shows 0,3 nickeliron (original Hilumin):
To itself: 105J
To 18650 + 80J
To 18650 - 75J
Could possibly a little to hot. But Im happy.
I changed the inputconnection to (in germany quite common) 2x10mm tinned copper an soldered 3 XT90 plugs to it. Now I can decide wether I weld with 2 or 3 lipos. Pictures attached with one 3S 5Ah 65-130C HK Lipo and one old 3S 4Ah 60C good quality lipo.
Calibrating at (3,85V) 1750A. So good range. Can go higher if I needed.
Pictures shows 0,3 nickeliron (original Hilumin):
To itself: 105J
To 18650 + 80J
To 18650 - 75J
Could possibly a little to hot. But Im happy.
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julian.koenig87
1 µW
eee291
100 kW
The shipping price sure has exploded since the 13€ in 2018. OMG
I wanted to buy the laser cut case and the firmware update tool, i expected it to be a total of about 50€ with shipping but 110€ is just insane. This has to be a mistake, right?
I wanted to buy the laser cut case and the firmware update tool, i expected it to be a total of about 50€ with shipping but 110€ is just insane. This has to be a mistake, right?
Attachments
eee291
100 kW
Value added tax
eee291
100 kW
Austria.
gotboostedvr6
1 mW
Can this welder be purchased as a complete unit?
Hi folks! I just received and assembled by kWeld, my first spot welder! Unfortunately out of the box I'm having an issue, but I think the issue is not with the welder, but I need some advice from folks such as yourselves.
I tested the kWeld first with an old retired 18650 scavenged from something long ago. I am welding 0.1mm nickel strip. I set the kWeld to 20 J, and it worked great.
Then I tried to build a simple 1S4P 18650 pack with brand new freshly charged Panasonic NCR18650B. The negative terminal has some sort of copper/gold colored coating (which must be conductive since I charged them up in my charger).
When I attempt to spot weld the nickel strip, there are a lot of sparks and the kWeld complains "Undercurr" and the resulting weld is, well not a weld, instead there the nickel strip has holes where the probes were touching, and the surface of the battery is pitted (green circle in photo)
I tried sanding this colored coating off (red circled in photo) to reveal the normal silver colored metal underneath. However that didn't improve the situation.
Am I doing something wrong? Any tips would be appreciated.
I tested the kWeld first with an old retired 18650 scavenged from something long ago. I am welding 0.1mm nickel strip. I set the kWeld to 20 J, and it worked great.
Then I tried to build a simple 1S4P 18650 pack with brand new freshly charged Panasonic NCR18650B. The negative terminal has some sort of copper/gold colored coating (which must be conductive since I charged them up in my charger).
When I attempt to spot weld the nickel strip, there are a lot of sparks and the kWeld complains "Undercurr" and the resulting weld is, well not a weld, instead there the nickel strip has holes where the probes were touching, and the surface of the battery is pitted (green circle in photo)
I tried sanding this colored coating off (red circled in photo) to reveal the normal silver colored metal underneath. However that didn't improve the situation.
Am I doing something wrong? Any tips would be appreciated.
Attachments
Last edited:
They look corroded, but perhaps that is the coating debris after sanding.
Keep in mind that if that coating is conductive, and it ends up in the space between the positive end and the cell can (negative) it's going to short the cell out. Doesn't have to be a direct high current short--just the dust of it plus humidity over time could create a "permanent" leaky current path.
If it is a highly conductive coating, it might mess up the weld because the resistance is not what the welder expects.
Also, if it's not what those cells normally look like, they could be extra caps installed on top of recycled garbage cells to make them look new. It's not uncommon. (they might be real panasonics, or random garbage cells re-wrapped to look like them).
Keep in mind that if that coating is conductive, and it ends up in the space between the positive end and the cell can (negative) it's going to short the cell out. Doesn't have to be a direct high current short--just the dust of it plus humidity over time could create a "permanent" leaky current path.
If it is a highly conductive coating, it might mess up the weld because the resistance is not what the welder expects.
Also, if it's not what those cells normally look like, they could be extra caps installed on top of recycled garbage cells to make them look new. It's not uncommon. (they might be real panasonics, or random garbage cells re-wrapped to look like them).
I see the gold coloured negative terminal on pictures of protected NCR18650B cells. Are your cells 70 mm long instead of 65 mm? If so, you're trying to weld to a printed circuit board. It would be very thin copper plated with nickel, then gold.
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Thanks for the info TDA78.
They are about 68mm long. Oh interesting, so these are likely protected cells. I've never really encountered those before. I can see those wouldn't be useful when building a battery pack with cells in series, but since I want to put cells only in parallel it seems they could be used, but only if I don't weld to them. :/
Guess I need to buy some unprotected cells.
I just assembled a new Kweld bought 10 months ago as a backup.
It works but I feel it has different performance.
The difference is the battery setup. Old has 4s30Ah lipo at 1700A CAL rating after test
My new battery is a 2s10p high performance 21700 charged at 3,6v right now for each series.
With first test of CAL it gives out 700A
What performance will I get from a fully charged pack at 8,4v? My estimate is 850A but still as you can se there is a difference in amps rating of my two setups.
My new and lower rating setup feels that the pure nickel 0,15 is very lose to the cell. I use 29 J and it it very good with my older higher rating battery setup.
I can guess the difference is timing but is this really the only difference?
Do I have to higher the Joules to counteract this new weaker battery?
I need to know what to do to get better performance.
Please any input is very appreciated!
It works but I feel it has different performance.
The difference is the battery setup. Old has 4s30Ah lipo at 1700A CAL rating after test
My new battery is a 2s10p high performance 21700 charged at 3,6v right now for each series.
With first test of CAL it gives out 700A
What performance will I get from a fully charged pack at 8,4v? My estimate is 850A but still as you can se there is a difference in amps rating of my two setups.
My new and lower rating setup feels that the pure nickel 0,15 is very lose to the cell. I use 29 J and it it very good with my older higher rating battery setup.
I can guess the difference is timing but is this really the only difference?
Do I have to higher the Joules to counteract this new weaker battery?
I need to know what to do to get better performance.
Please any input is very appreciated!
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Read and understand the power supply requirements detailed on page 7 of the operating manual.
DogDipstick
100 kW
Very generalized statement that is not so true in 2024
we don't know which exact cells he uses so it could be true of courseYou can't weld onto the protection board, but since it is a circuit board, you should be able to solder to it (unless it's one of those metallic boards) - and since it sits apart from the cell itself, that shouldn't take any damage.
I will read.
After charge to 3,8 per cell the power is no 750A tested with a steady hand.
My question is regarding the options I have and if someone have seen a similar pattern in their usage of their Kweld.
I can build a more powerfull battery or use 3s which seems to be better.
I will read that part of the manual first.
Thanks!
Suggested is 3 or more liion or lipoly in series
3s seems to glue the nickel to the cells correctly!
I'm, very happy!
3s12p Molicel P26A 35a rated. Here they give out about 87,5Amps. My 21700 cells former pack have a a maximum of 75 amps. Still fully charged they could give out some more of course.
