The new version is more resilient to 4s lipo. I’m not sure but maybe the side effect is that requires a better 3s lipo. I used a top lipo since day one and the flux times always were as posted at 1st post. I can’t edit it anymore but seems I have to recommend the best possible lipo now on.
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I was researching another arduino spot welder that runs on 3s, and he’s measuring 1000-1500 amps for a pulse. 25r also have relatively high internal resistance, I think, which will hamper performance.
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So from what I’ve noticed
-frozen weld cables or cold weld cables need less MS and less multiplier as the resistance is lower. -as the weld cables get hotter the resistance increases, making the MS and multiplier higher. -having a big pack helps(I use a 32Ah 4s 10C - which can easily do 320A continuous) -less batteries being welded requires less timing. Ie when I weld a 5p pack vs a 2p pack. I lay the nickel on and then hold it down across. Resistance changes the welds. Ie for 5p, on a 4s power supply, 4.5ms x2 works well, but if I used this setting on a 2p pack I would burn a hole. The 2p on 4s power supply needed 2.5ms x1.
Basically you need to account for temperature (air) as well as relative humidity, temperature of the welding wires, the resistance of the material (nickel), and the resistance of the pack surfaces (how many cells are attached to the strip).
About the humidity, below 45%RH, is considered dry, and air is likely to hold static charged ions making burning holes with to much power even more likely. Weld in 55-65%RH and it will suppress the extra sparking from charged ions in the air.
Regarding heat of the fets…I easily got the fets upto 48c cutoff after 30-40 welds in a row… I added my plates and highest I’ve seen is 31c after 290 welds in about 20 minutes. Basically I put this thing through the paces hard lol.
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good to know, to start i’m putting a 2p pack together and welding 40 x 10 x .15mm nickel so don’t think material resistance is the culprit. and environmental conditions are ideal.
aside from the battery, only other bottleneck may be the 10awg wires coming off the battery, it’s about 18" in length, maybe that’s adding too much resistance? i could probably double that up and see if it makes a difference.
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Maybe I’m not sure my wires from lipo tab to welder are about 11".
A test you could try, if you have some dead VESC laying around… Add a cap rail right by the input of the welder… Then you can rule out whether it’s length of wire or C capability… As the caps should fix anything if it’s from resistance during the burst current.
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I am rebuilding my battery so I can fit it in a new enclosure and so I could weld on higher quality nickel (apparently the stuff I had on was just nickel plated). I ripped off all the old nickel and cleaned off the positive and negative with flush cuts so I could get a smooth surface to weld on. There are two leads that the nickel will just not weld to. I have tried cleaning it off again and raising the ms. I also recharged my battery to make sure I was getting the most power out of it. But it just wouldn’t stick. I attached a picture of the battery surface and a piece of nickel that I had tried to spot weld. Honestly it doesn’t look the weld went through the strip. But I wasn’t comfortable turning the ms past 7. Any advice for what I could do?
did you put insulator rings on the anode end of the cell? if so, not necessary.
I’ve done almost the same thing with my salvaged cells, ground off the welds.
only tried to weld two cells so far but haven’t encountered what your experiencing, maybe I’ll see the same thing once I get into this next build.
you may just have to resort to soldering if the welding doesn’t work on those specific cells.
3300 maH 3s lipo 40c. I had it set at 5 Ms at first, but bumped it up to 7 Ms since it wasn’t welding it. @E1Allen
Yeah I’m afraid I might have to solder it, which I really didn’t want to do. I’ll try a few more things tomorrow though.
Each maker has different performance. Please upload a picture.
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Here’s a picture of the settings I was using it in. I was using the switch when I was spot welding. I inspected all the resistors and FETs and none of them looked burned up.
So, I tried spot welding nickel to nickel and I went all the way up the 11 ms and it still wouldn’t stick together. It seems like it’s just not putting out as much power as it was before. Could it just be that I have a crappy battery? It is a 40C but it was on the cheaper side.
Brand of battery? Even for supposed good batteries the C rating is overrated. I’d be willing to bet your battery just isn’t enough.
The brand is Floureon. I think it’s just a cheap brand. It really doesn’t seem to be putting out enough current
So you do 3 pulses? Is that safe when you’re welding to a 18650?
So here’s this.
Nickel to Nickel 4.0ms, 3x, 2ms pulse delay
First strip of nickel 0.15 to 18650 3.5ms, 2x, 2ms
Second strip of nickel to 18650 ie nickel to nickel 6ms, 1x
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