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    Spot Welding Copper Strips to 18650 Battery Cells

    Yeh the layout was quite constrained and it had to be curved to fit the harness, would have been possible to do them in blocks of 6 rather than 3 to end up with a single pack but then would have needed twice the copper thickness as each plate would be carrying the full current. I can't spot weld...
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    Spot Welding Copper Strips to 18650 Battery Cells

    Finished pack, just bunged some JST on there for now as I had them already, far from ideal but will let me check the cells. Cells were within 2mV absolute straight out of the box which was amazing. utYveWc6Wrg
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    Spot Welding Copper Strips to 18650 Battery Cells

    Power leads have been attached. I 'butterflied' 8awg silicone cable and soldered to a piece of copper which was then welded to the cells. I formed a channel in the copper to wrap around the wire increasing the joint strength. Now just need to attach some balance leads (no BMS in this pack). Any...
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    Spot Welding Copper Strips to 18650 Battery Cells

    Battery is a Numax XV31MF Heavy Duty Ultra Deep Cycle Leisure Marine Battery - 12V / 105Ah / 740EN / 925MCA. Not mine I borrowed it from the guy i'm building the pack for, it is brand new. CCA is rated at 740A. https://www.amazon.co.uk/Numax-XV31MF-Leisure-Marine-Battery/dp/B0761TW797/
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    Spot Welding Copper Strips to 18650 Battery Cells

    Its going on a hang glider.
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    Spot Welding Copper Strips to 18650 Battery Cells

    I've welded my packs up, 2x16s3p 40T. I used 0.1mm copper and plated steel patches, arduino welder , 800cca and 25ms. Went very well although electrodes get hot so a few pauses, took about 2 hours.
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    Spot Welding Copper Strips to 18650 Battery Cells

    I think you might be right that 0.1mm would work for me. I just used a couple of online pcb trace calculators, taking a strip of 0.1mm copper, 16mm wide between two cells with a temperature rise of 5 degrees C it can carry 28A, 10 degrees 38A, I2R losses at 25A would be 67mW, voltage drop 3mV...
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    Spot Welding Copper Strips to 18650 Battery Cells

    Is that 30A per cell? 30A thru say 22x0.1 = 2.2mm^2 copper is quite a lot is it not? Do you have a picture of your pack? I'm extremely constrained with the layout so I can only get 50mm of plate in there to carry the series current of three cells. 50mm of 0.1 is 5mm^2, at 75A for three cells...
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    Spot Welding Copper Strips to 18650 Battery Cells

    22A per cell for 30s bursts, about 10-15A continuous (2 min bursts) although the whole system will be off for most of the flight. These are 40T cells. The purpose of placing pure nickel down first is to get an excellent weld to the cell. Then placing copper over the cell tips and bending the...
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    Spot Welding Copper Strips to 18650 Battery Cells

    Splits don't seem to help much with 0.2mm copper with my arduino spot welder the problem is the overall thickness of the layered buildup and the massive heat sinking of the thicker copper. As I said above you can get excellent welds onto the cell with 0.1mm copper and plated steel patches. 0.1mm...
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    Spot Welding Copper Strips to 18650 Battery Cells

    I have now done some experiments with 0.2mm copper and the arduino welder in an sandwich. I can get a reliable connection through the first layer of 0.15mm nickel into the copper however not from the copper down to the cell. If I take a strip of nickel and bend it so it wraps around the copper...
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    Spot Welding Copper Strips to 18650 Battery Cells

    Some more tests still using the empty cells. 1. 0.15mm pure nickel 10ms - ok weld but not enough to tear the strip on all spots 2. 0.15mm pure nickel 17ms - excellent weld 3. 0.15mm steel -> 0.1mm copper 35ms - excellent weld Test 1 is not really any good as the weld wasn't strong enough...
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    Spot Welding Copper Strips to 18650 Battery Cells

    They were empty cells, literally just the shells, using them to get the welding settings correct. Do you know of any pictures anyone has taken of the inside of any cells after welding that I can compare to? I will do some more tests this time with just steel-copper-steel strip sandwich and see...
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    Spot Welding Copper Strips to 18650 Battery Cells

    Yes of course. But how do the welds look (I haven't got anything to compare it to) are they too hot or OK? Also what pulse duration do people usually use on the arduino welder? I've now reduced it to 32ms which still gives an excellent weld.
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    Spot Welding Copper Strips to 18650 Battery Cells

    Hi, I'm looking for some feedback on some tests welds. This was 0.1mm copper with no slit with a small square of 0.15mm nickel plated steel strip on top. I used an empty test cell so I could cut it open see the welds from the other side. The welder is an arduino spot welder powered from a 12v...
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    16S SMPS charger cheap and easy

    I'm new here but thought the following might be of interest. I'm building a 16S3P 60Ah pack (EIG cells) and needed a quick and dirty charger. I couldn't find a meanwell with the required voltage so took a punt on a £50 NVVV S-800-70 (70v 800W 11.4A) brick from Amazon. The quality of the brick is...
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