Has anyone taken these apart?

MBF Dan

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May 14, 2021
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That pack has 6 NCR18650F cells in it. I cut the top off and there is a circuit board which I cut all the wires going to it from the cells then cut the back side off the pack behind the circuit board but as you can see the pack is just pumped full of glue and I damaged 3 of the 6 cells trying to pry them out. I have 2 more of these packs but honestly the way this one came apart I wouldn't bother taking the other apart I will just toss them into a recycling bin.
 

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italianuser

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Full of glue🤦‍♂️When I find tough-to-open containers I try to hack through the middle line: where the two halves of the box are "clipper" together. Can be very time consuming but it could be a clean open, ehm... when glue free
 

MBF Dan

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Full of glue🤦‍♂️When I find tough-to-open containers I try to hack through the middle line: where the two halves of the box are "clipper" together. Can be very time consuming but it could be a clean open, ehm... when glue free
The top was where the case was closed the entire part you see in the photo is a single injection mold so they pumped a ton of glue in the bottom then pushed the pack of cells down into it I am guessing. Even with the top and one side cut off the 3 cells at the bottom of the pack of 6 where so stuck I damaged them trying to get them out and broke the zinc strip joining the cells before the top triangle of cells could be pushed forward out the open side I had cut free.
It really wasn't worth the risk of shorting the cells the way I took it apart and I don't see a better way in.
 

MBF Dan

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Positive side: you know what to avoid next time :D
Unfortunately they came in the box of mixed mostly medical batteries from battery hookup. Guess that is why they are cheap. Ofcourse my 80lbs order had 40lbs of laptop batteries which hardly seems to fit the description of mostly medical with a few laptop batteries.
 

MBF Dan

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if I was starting out I would go with these https://www.batteryclearinghouse.co...h-high-drain-20a-cells-in-a-tool-battery-pack Greenworks commercial 72v battery packs
<edit> if I was using 18650 and needed power cells
later floyd
I have looked at those but I am looking at about 3000 cells to get a 20kw pack. So the price difference definitely adds up fast.
I am asking out of ignorance here but I question if I need tool batteries with a typical high discharge capacity? My goal is to design the pack to run a 4kw motor for 5 hours so it seems to me that I would not be looking for high discharge rates but rather about a 0.2c discharge. Which is what made me think I really wanted higher capacity slower discharging cells. But I will admit I am as green as you can get when it comes to lithium ion so I could easly be missing something obvious.
 

floydR

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I see your point. I am sure you don't need the cells to be able to push 20A. Was thinking ok it is a tool a tool cell is just the thing. One plus with going with higher mAh cells is fewer connections Always a plus in mobile applications even if they aren't high drain cells. 2400 cells for14s/172P 20kWh with 2500mAh cell 1960 cells @ 14s/140p 21kWh 3000mAh
My cell purchases were over 8 months time frame or so. A bit here and a bit there. less stress for your cells even at .2c discharge.
later floyd
 

MBF Dan

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I see your point. I am sure you don't need the cells to be able to push 20A. Was thinking ok it is a tool a tool cell is just the thing. One plus with going with higher mAh cells is fewer connections Always a plus in mobile applications even if they aren't high drain cells. 2400 cells for14s/172P 20kWh with 2500mAh cell 1960 cells @ 14s/140p 21kWh 3000mAh
My cell purchases were over 8 months time frame or so. A bit here and a bit there. less stress for your cells even at .2c discharge.
later floyd
I expect to be doing most of the build this comming winter. I did budget this peoject with some unexpected income I have had lately but my time is rapidly vanishing as I am getting the haying season started. Always busy on the farm. Right now I am just breaking down some packs at night before i go to bed. It is far better than watching TV...
 
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