what is your spot welder setup? just a manual button?
Shit I thought you just torched the nickel a bit but those bubbles down the side are crazy
That’s from the glue 
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looks like the result of adhesives to me.
edit: ninja’d!
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Yes. Just manual button.
So you have three reasons that Individually or combined resulted in this behaviour.
- Manual Button
- Wrong Spot welding angle
- Space between nickel and the battery
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What exactly affects peak performance? The fact that it was previously welded? They have zero charge cycles right?
Oh haha sorry I’m on my phone right now
The fact that the burst (which damaged the cell) could have changed the IR
theres a lot of cells sold on endless-sphere that are not used but with weld marks. i dont know why or where he gets them from but he sells a huge amount and they show not to have any reduced capacity. the weld shouldnt do anything. it doesnt heat the cell noticeably.
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I just edited my last Post to make it more clear.
A Spot weld shouldnt do any harm. Thats why we are Spot welding. Lhb just meant that the Pack wont reach peak Performance with this damaged cell
Yea that makes sense. I was just curious how the non affected cells in that parallel group could have been damaged. Thanks.
is that a common method of spot welding? I havent heard of that before and it sounds pretty sketchy.
A bit? If you are on a budget. I know @darkkevind does it and I don’t think he have had any problems. I agree it’s a bit sketchy after this experience. Have to go and read about audrino timers to make it work better.
Just something I thought of. Nothing of this is facts. Just a theroy.
The 2 welding tips is pretty identical but one of them is a bit longer and probably bigger (can’t remember). What have happend might have been that one of the tips had more power go through and made a bigger impact. In 1st weld one of the “dots” in the nickel strip is much bigger than the other. In 2nd weld is there also a much bigger “dot” right above the other big “dot”. That means one of the welding tips might be the problem?
You didn’t have the electrodes properly connected to the nickel and you therefore created a very high current arc. That’s what blew a hole in your cell.
Be very careful that they are both touching the nickel firmly before clicking that button! Click that button super-quick too!
Take a look at my demonstration video… You’ll see how long to click for… It’s literally on and off immediately.
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It’s a problem of contact. I was also surprise how much pressure you need to apply to assure a good connection. To run test use a nickel strip and a cutter blade. I read it mimics the real situation. Anyhow really put a firmly pressure with your hand when welding and you will see that it won’t happen anymore. Anyhow I said before I really suggest to attach an Arduino. It is so cheap and makes your life a lot easier. I can give you the script that I used and then you would need to adjust to your system power (you need to adjust the pulses time). Although the code it’s really easy I based on the led script present in the Arduino library. You will only need to connect the Arduino to a switcher that opens and close the circuit when the Arduino gives the stimuli starting from your momentary button or pedal. I can post also the Arduino connections so you will only need to reproduce them. Load the program and adjust the time in the program. That’s it 
Edit: moreover I see form the picture you posted that most of the welds went through the nickel strips. So you are applying the current for to long. Which is normal by hand. In this way even if you don’t get the burnt spots, the connections between the battery and nickel strips are gonna be too weak.
Last edit. When I set the system these were the welds I got. Really strong.
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I took the whole pen apart and now I have two wires with copper tips. This way and the old way doesn’t work good enough. I have to get some Arduino in the system. I’m 90% sure I’ll just get the Arduino spot welder but it’s a bit pricey. What Arduino do I need to use that script you got?
Your welds looks much cleaner. How much is the timer set to?
I have several arduino and I use the Arduino uno pro but that comes a bit pricey. Just get a arduino nano, the script will work too. On Ali is at 2-3 $ but takes time. A bit more you will get from where you leave. Nano V3 ATmega328/CH340G, Micro USB, Pin headers NOT soldered. Compatible for Arduino Nano V3.0 http://s.aliexpress.com/nQr6vayq?fromSns=Copy to Clipboard You also need a switcher which I had it but it will cost a bit more. Locally you can buy from Rc component for like 20 euro, otherwise for less I guess from Ali
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These the connections on the Arduino.
Basically just pins front he output and the 5V line with a resistor. I don’t remember what I used but I think 5Koh resistor but I will check. The Arduino is powered by an power bank. It is a separate circuit that just send the signal to close the circuit at the switcher level following the script you loaded. Then the switcher is connect it to the spot welder as the momentary button. The momentary button need to be connect Tot the Arduino.
In the picture you see a button directly connect to the spot welder, is because I kept both the option. There is actually another button connect to the pin 13 on the Arduino. I will take better picture when back from holiday next week.
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