So I wanted to use 12s3p samsung 40t with this BMS: https://www.lithiumbatterypcb.com/product/12s-13s-14s-15s-36v-48v-58-8v-smart-bluetooth-bms-with-20a-to-60a-constant-discharge-current-with-uart-and-rs485-double-communication/ (12s 30A), in boundmotor’s carbon fibre deck: https://boundmotor.com/product/carbon-fiber-skateboard-deck/ , on website they say that you can fit only 12s2p pack of 21700 cells but i’m quite sure that I can fit 12s3p too. Can someone doublecheck if that’s possible because this is gonna be my first battery pack and I’m a little concerned?
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Absolutely love the Weller solder guns. A small annoyance is that the tips don’t last so long.
Am I the only one?..
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Definitely not the only one. I love both my Weller guns, but the tips are absolutely a consumable. Cleaning them with a sponge and/or a wire bundle helps them last longer
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The hard part of putting 21700’s in this deck is the height. 21mm diameter on the cells + 2mm for fish paper + 2mm for balance wires + 2mm for heat shrink, and you are well over the 23mm height of that deck.
I am speaking from experience here, I owned that deck and tried to build a 21700 battery for it.
Ended up just going with an 18650 battery because if the lid of the deck bows down at all and presses on your battery, its only a matter of time before something shorts somewhere.
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There might be power/timing/tip adjustments to be made but the difference between the two columns of welds is interesting.
For most of the cells the left column is a lot better than the right (in the photo), To me this could indicate an angle or pressure change? Which column is done first? If it’s the right one then perhaps doing that brings the strip down closer to the cell’s contact so the left column is then better?
Just tossing stuff out there…
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What about 12s4p of samsung 35e? BMS is gonna hardly fit but is it possible. And how they fit 21700 battery in bound d1 for example?
It’s done as pairs as middle top bottom, the left is the negative and goes down first then I press the right (positive) to trigger the autowelding. Both are the same angle but the positive electrode oblates faster
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@ MrDrunkenMobster
Edit: I see he’s already on it as usual. 
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I would reccomend to you that you make a rectangle of cardboard with the stated dimensions and then lay out parts (or paper models of each part) on the cardboard so you can really visualize how much space will be left over.
Also keep in mind that the bottom of the cutout is not flat all the way across. It bumps up as it goes into the ESC compartment, becoming too narrow for more battery. So you cant use that whole 57cm, rather only the 43cm listed for the battery area.
From my calculations, you wont even be able to fit a 12s4p of 18650 in there. Check out this screenshot:
This is from this handy dandy calculator. Notice how I used 19mm instead of 18mm, and 66mm instead of 65mm. This is to give you some small amount of breathing room in your pack. Realistically you will want even more breathing room than that. Even with this conservative estimate, the most cells you can fit in there are 46, two short of a 12s4p.
This is for 21700. You are correct that you can technically fit a 12s3p in there, but again, height is going to be your problem here.
I dunno man. Bluetooth balance wires? A 45lb middle school girl doing their test rides? Hammering their 21700s flat before building the pack? However they are doing it, I doubt it would stand up to our safety standards here in the Battery Builder’s Club.
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Just gave this a shot. Great recommendation. I’m not sure it’s faster yet, but once I adapt to that hand movement I can imagine it will be.
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What pattern are you making? On the negative it has to be non concentric right?
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Got some work done on the 12s4p 40T I’m making for my Demonseed.
These pre cut nickel strips from DRI are awesome.
I’m looking forward to getting further into the process to see the PCB come together.
I just got the wiring done and welded a couple of groups. So a ways to go.
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Clean work!
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I reground the tips and recalibrated the welder, welds are back to being solid on both ends! Thank you guys 
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Someone killed 2 12v car/truck battery tonight took one of the 2 out to test the amps ratings (500 amps load for 15 sec, CCA is 1050) and when putting back someone put it backward (positive to negative and negative to positive) loop closed between the batts and boom big spark followed when the - wire get on the + pole, everyone ran away so fucking fast. The pole got red hot till it somehow disconected. Our guess is that it got so hot it just melted till the short was cut to an end) UNTILL the teacher touches it to make sure it was disconnected but caught on fire ( small flame but still)
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Get a piece of copper wire and bend it in to the shape, my brothers doing that for like 20years with his weller gun
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Cool idea… do you know how thick the copper wire? I have here 1.5 mm which I can test.
Not sure, didnt see that iron for quite some time after I bought my own haha
Just measure what size is the wire now
It probably wont have the thermal mass as the original but for small wires it doesnt matter
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