I guess I need to make 72v 35ah battery pack

Finally the turtle boat from china arrived. I think I'm ready to get started now. My plan is to use this 0.20 copper with 0.15 nickel. I have no idea what to set the KWelder at. I'll have to practice a while before getting started.
20240618_181823.jpg
 
I started practicing my welding. So far I don't feel like it's going so well. This is 0.2 mm copper, and 0.15 nickel. Seems like it can barely work even set on 500j. It's kind of inconsistent too. It might make a good weld, but the next one barely holds. Suggestions are welcome. I just ordered some 0.1 mm nickel to see if thinner nickel will work better. weld test.jpg
 
Obviously I'm going to need to make some changes to my plan. Plan 2 is to try 0.1 nickel instead of 0.15, with my 0.2 copper. I don't have a lot of confidence in it though. Plan 3 will involve gluing the cells together without the plastic holders and hand cutting copper busses from 0.1 mm copper sheet.
 
Theodore Voltaire said:
Obviously I'm going to need to make some changes to my plan. Plan 2 is to try 0.1 nickel instead of 0.15, with my 0.2 copper. I don't have a lot of confidence in it though. Plan 3 will involve gluing the cells together without the plastic holders and hand cutting copper busses from 0.1 mm copper sheet.
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Plan 3 is something I did many times, it works very well with kweld. in alternative recently I have been using the connections in the photo bellow, they are 0.3mm cooper and have a weld area made of 0.15mm nickel.

S54d3332a54c942a99d367bce3ce97533R.jpgS72aa40548c1a4a6e9f20ebe763bde2a4V.jpgS7b99ba4328884faebb7899c43b0640eeB.jpg
 
I figured out a way to salvage the plastic cell holders. It's very easy to snap the little tabs off the holder which allows the cell holder to slide down on the cell. This gives me a flat surface to weld on, but keeps the cells spaced apart.Modified cell holder.jpg
 
Portugaline said:
Plan 3 is something I did many times, it works very well with kweld. in alternative recently I have been using the connections in the photo bellow, they are 0.3mm cooper and have a weld area made of 0.15mm nickel.

View attachment 355350View attachment 355351View attachment 355352
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I was searching those copper/nickel busses yesterday. I wasn't able to tell from the pictures if they were copper on the bottom or not. Sounds like you're saying they're nickel. What would work best is if I could find those kind of busses with spacing to fit my plastic holders. I'm trying my best not to have to glue the cells together, but that's on the table.
 
Theodore Voltaire said:
Obviously I'm going to need to make some changes to my plan. Plan 2 is to try 0.1 nickel instead of 0.15, with my 0.2 copper. I don't have a lot of confidence in it though. Plan 3 will involve gluing the cells together without the plastic holders and hand cutting copper busses from 0.1 mm copper sheet.
Click to expand...
Are you using a good power supply that can deliver adequate current for the kWeld? I ask because on my first spot welding venture I was using a LiPo pack that didn't have quite enough punch; I added another pack in parallel and it produced much more consistent welds (I forget how thick the materials were; but it was also a coper/nickle sandwich.).
 
pwd said:
Are you using a good power supply that can deliver adequate current for the kWeld? I ask because on my first spot welding venture I was using a LiPo pack that didn't have quite enough punch; I added another pack in parallel and it produced much more consistent welds (I forget how thick the materials were; but it was also a coper/nickle sandwich.).
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Having zero experience I can't say if that's a problem or not. I'm using a brand new truck battery that has 900 CCA. I'm thinking if I need a power supply stronger than that I'm doing something wrong?
 
I think I found copper/nickel composite busses for 21700 cells that have the right spacing for my holders. When the turtle boat finally gets here I should have at least couple of options to try.copper strip.JPG
 
Thanks for the updates on your progress Theodore. I’m now looking at building an interim 24s 8AH headway LifePo4 pack; mainly because I have the high amp cells and a massive 8 amp 87.6v charger. Mine is a 2011 and still has the v2CA so I will probably upgrade to a v3 on the bars, leaving the v2 in the frame top for now.
 
DCMotorworks said:
Thanks for the updates on your progress Theodore. I’m now looking at building an interim 24s 8AH headway LifePo4 pack; mainly because I have the high amp cells and a massive 8 amp 87.6v charger. Mine is a 2011 and still has the v2CA so I will probably upgrade to a v3 on the bars, leaving the v2 in the frame top for now.
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Thank you for the encouragement.
 
WooHoo the turtle boat from China arrived. I've now tested 4 different welding options and spoiler alert, the winner by far is the copper/nickel composite bus. After finding out my Kwelder couldn't weld a 0.2 copper/0.15 nickel sandwich, I tried it using 0.1 nickel but I wasn't much better even at 500j. I couldn't trust it. Next I tried a sandwich of 0.1 copper/ 0.1 nickel. this actually worked pretty well at about 125j. Lastly Mr EE and I tried the copper composite. It's some pretty impressive stuff. It made great solid welds at only 100j. This is what it looks like. The copper is 0.3, but they did some kind of magic trickery at the weld point. What I don't fully understand about the weld point is on one side it's nickel, and on the other side it's copper. I thought it would only be nickel. In Chinese they told me something is 0.12, which I assume is the copper, but what abut the nickel? They told the truth when they said it would be very easy to weld. The only thing I don't like about it is it this kind only fits 21700 cells glued together, but I'll deal with it.
 

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Through Aliexpress I contacted the factory in china that makes this composite buss. They said they can make it in various sizes that fit both 18650, and 21700 with or without the plastic holders. They're going to send me some with the right spacing to fit my plastic holders. 22.5mm fits 21700 cells glued together. 23mm fits 21700 with the plastic holders.
 
Theodore Voltaire said:
Through Aliexpress I contacted the factory in china that makes this composite buss. They said they can make it in various sizes that fit both 18650, and 21700 with or without the plastic holders. They're going to send me some with the right spacing to fit my plastic holders. 22.5mm fits 21700 cells glued together. 23mm fits 21700 with the plastic holders.
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Sorry the delay, here you have a stealth bomber battery I’m finishing now. It’s a 21s9p with 21700 cells and the copper bars I told you about. This will fit the stealth bomber frame without any problem.

IMG_4085.jpegIMG_4079.jpeg
 
Portugaline said:
Sorry the delay, here you have a stealth bomber battery I’m finishing now. It’s a 21s9p with 21700 cells and the copper bars I told you about. This will fit the stealth bomber frame without any problem.

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That looks good, but I don't think it would fit in my frame. Your bike must be a clone?

My composite strips came a couple days ago, and they fit. I plan to start welding tomorrow on Saturday.
 
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Theodore Voltaire said:
That looks good, but I don't think it would fit in my frame. Your bike must be a clone?

My composite strips came a couple days ago, and they fit. I plan to start welding tomorrow on Saturday.
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My bike is the Australian stealth bomber just like yours, it will fit. I have one exactly like this in mine.

11,5cm
33cm

See bellow

IMG_4086.jpegIMG_4087.jpeg
 
Portugaline said:
My bike is the Australian stealth bomber just like yours, it will fit. I have one exactly like this in mine.

11,5cm
33cm

See bellow

View attachment 357129View attachment 357130
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That's good to know. I did consider something like that. With 21700 cells I could make a 40ah pack fit, but decided against it for 2 reasons. I don't want the extra weight, and gluing all the cells together in an irregular shape seems so labor intensive.
 

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It looks like the fold method isn't going to work very well with my 0.3 copper composite. We're considering something like this. Also can anyone tell if I'm running too much current on the welder?


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