Building my first battery pack, and I cannot for the life of me wrap my head around building a 12s5p battery pack design outside the traditional “brick” rectangle design with rows of 5, column of 12. However that would be too big to fit in my enclosure. Does anyone have a resource or a dummies guide to pack design? I have seen slim 12sp5 packs for sale but ,my mind just can’t process different designs…
I know this post makes me sound incompetent, I’m a resourceful guy, work on cars, can work my way around a multimeter, etc. but this battery pack design has lost me sleep thinking about it this week
Here’s a picture of a 12s4p pack, which will just be one cell narrower on each side. What’s specifically confusing? With a 12s5p pack, there’s only one way to design it that’ll fit in most enclosures.
Maybe my confusion is stemming from how to connect…or what to use to connect each set of 4… it’s essentially rows of 4 parallel connected to the next row of 4, and so on for 12 in series correct? That being said how do I connect them? It looks like there are angled plates?
Also here is a picture of the enclosure I got with a 12sp5 battery (or so they claim) installed in it. I am not opposed to buying a new enclosure but the board I bought was specifically made for it. This picture makes it look like the batteries are stacked at least 2 high though vs your pic where they all lay flat I believe?
it’s quite imperative you get that series connection between the “top” and “bottom” levels large enough to spam with spot welds. if you dont have like just oodles of welds that series connection becomes a choke point for current and gets extremely hot,
you can also just fold tge tabs in opposite directions and connect via soldered copper braid/wire
if you spot weld them, make sure you got like some FR4 orrr something similar burn ish resistant tjin and sacrificial. between the tabs and cells to protect them as you spot it up. (no, fishpaper is not a good option, it burns pretty easily)
lots of good advice already, my 2 cents: open the pack you have. get some new heat shrink and carefully open the pack you plan to copy. you should be able to pull the shrink and then the fiberglass sheets to get a good look at the pack you have. then take some photos and post them up. if you’re not familiar with the build method I’m sure someone here can shoot you in the right direction to get good supplies for your build.
if this is your first build and you haven’t found the wiki:
it has some good general info and stuff.
there are also quite a few battery builds posted up here with a little searching that have tons of pictures showing how to use and make custom nickel strips for odd/complicated pack layouts like the one you are planning.
I also found it helpful to use a 3d cad program to do the cell layout - if i don’t see it it is hard for me to visualize. something like tinker cad or mater control are free and can be learned pretty quick if you haven’t messed with 3d printing and know them already. just make a cylinder in the correct dimensions and start fucking around… or when you get the cells grab some masking tape and just start arranging them - when they are at shipping charge level and not connected in parallel yet they are relatively safe to play with as long as you take basic precautions not to short or damage them
Thank you! I think this layout will actually work. I just want to make 100% sure, when you mention tabs you are talking about the big old “ears” on picture #3 that connect the “smaller pack” to the “bigger pack” correct? I do plan to spot weld for simplicity sake.
Also where do you buy those nickel strips in those polygonal shapes if you don’t mind me asking? I have seen similar ones with holes in the center in that shape but I have yet to see solid plate ones like the ones you’re using
also, yeah, the ears between the 2 sub-packs if you will. i’d say it’s easier and more peace of mind to solder wire/braided copper between them, I only welded mine from prior experience (with thermal testing) and I have little to no space in my enclosure.
