Also you can get BMS stuff from us UK vendors. Might save a headache shipping small stuff from the US (I’ve been waiting like 5 months for some stuff from @surfnacho D: )
Apex Customs: Small Daly BMS (10S/12S/14S/16S)
Me: DALY Lithium Ion (3.7v) Smart BMS for 12S/10S – Nexus Boards
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Tried to edit comment not delete, thanks for your help
Which
do you use
I have this one. I’d advise against it. It works well, but the base is not heavy enough in conjunction with the arm force. The higher end x-acto cutters are pretty nice- much more fluid cutting, or a commercial cutter.
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Daly makes them but will not post them. I’m not sure why.
You can just ask for them and they will be “custom”
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Exactly the same one as Static. Cheap and effective for me, but I probably use it differently to him.
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How should I layout my battery? I’m thinking of using the second orientation.
Also I guess a better question is, does it matter?
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I would personally go with this one:
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I did my best to prevent BMS leads from touching. Another lesson learnt in battery building is to be sure I test the BMS position first. In this case, I would have been better off moving the BMS to the side as it would have resulted in a cleaner result with not so many overlaps.
Ohhh well, the job is done now and it’s charged to 50.1 so happy days.
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My only comment is that for your next pack try to avoid the center 3mm of the bottom of each cell. That is set as a “no weld” zone by the manufacturers due to that being the location of the internal spot weld for the negative connection metal tab from the spiral roll of stuff in the cell.
Welding externally to that same point could potentially affect the quality of the internal weld. I wouldn’t worry though about this pack as long as it tests out well. It’s just a “best practices” thing to make sure nothing could potentially happen.
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Sooo many little bloody gotchyas, another item added to my little black book of battery building tips and tricks. Thanks, heaps @Battery_Mooch . What amazes me is how the professionals make it look soo good and easy. Building a better is time-consuming, stressful but also very satisfying in the end. After I took those pictures I spotted something I wasn’t happy with too so I had to fix it. There was a BMS lead sitting on a P group nickel join with no insulation below it 
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Made my own jig for spot welding my pack. There are grooves on the rear side that go around the nickel and the magnets pull the nickel up into the grooves so it doesn’t move.
Also made a tool for cutting into even pieces and for rounding the corners.
I’ll be trying to round the corners with 6 0.2mm pieces stacked at once with my dremel metal cutting wheel. Any tips for that?
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That’s nice work there, would you care to share the stls?
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I don’t mind but it’s only specifically made for my battery and I didn’t model it parametrically so I don’t see how it would be too helpful? Which ones do you want? The cutters I guess would be helpful and you could pretty easily rescale those?
Yeah I was hoping both. The jig would help me model my own with design for other sized batteries and p groups. The cutter is way useful as well to rescale.
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Enjoy!
For reference, I am using 77x30x0.2mm nickel.
spotweldguide.stl (421.0 KB) cornercutguide.stl (48.2 KB) nickelcutter.stl (6.5 KB)
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High speed, light pressure, and you probably want to mark out the radius and clamp those pieces together before you start cutting, because the heat will likely melt your 3d printed jig, and the vibration will make the pieces want to shift around relative to eachother.
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I’ve got my clamps ready. I forgot about how hot metal gets when cutting it. I think I’ll try to use the plastic as a guide for a corner and if it noticably melts then I’ll just use it as a drawing tool like my other cutting guide.
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What’s cookin all? I’m in the process of building my second pack and originally had planned on doing cell-level fusing to make this pack as safe as possible. That plan has since been junked due to several issues. Instead, I’m considering fusing the main pos wire w a 100 or 150 amp slo-blo mega fuse. I wanted to get a sense as to how many people are using a fuse here and what the general consensus is re risk if this fuse is not in place. Pack is a 12s4p w Murata VTC6s.
As an aside, I will most definitely be fusing the charge port. Thanks and cheers!
No need to fuse the discharge. But if you have to, I’d say go 200A. Better if you don’t, blow the fuse and you lose your brakes.
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