Just got the first part of my EVE230 shipment (UPS split it up for some reason, so some today, some tomorrow, weird). Opened the first box, packed super well. I was surprised however - no welded studs. Interesting. Maybe only the 280 or 304 has welded studs?
Also, the bus bars look to allow some flex based on the hump look. Any idea the current rating? They are two layers, evidently. My max DC load is expected around 200A. I'm expecting I'll probably need to get bigger ones, but I thought I'd see what showed up first before I bought more stuff.
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As your picture shows (beautifully) the supplied "bus bars" are actually a pair of super-thin smaller ones, held together with shrink-wrap tape. The bend can help to handle a bit of expansion and shrinkage as the cells become more or less charged, but the cross section (looking from the end) is very small, perhaps the equivalent of AWG-8 wire. It's going to have increasing resistance above 40A, and all that heat goes into the battery. If you stay with only these Docan-supplied bus bars, you should definitely get more of them. With a small ring terminal also attached under the nut, and maybe a washer as well, the supplied posts can handle 4-6 of the thin ones.
I received the same battery cells and bus bars just a couple of days before your first ones arrived. But I also had some slightly longer high-quality bus bars lying around (originally planned for a 270Ah battery pack), so I drilled a new hole into 3 of those (making each fit my 230A cell post centers). They were cut and drilled for 270Ah Eve cells by a forum member and offered in a group buy, back when the forum supported such buying/selling arrangements. I was thrilled to get them, and have no idea how to obtain anything comparable from a normal online seller. I stacked the Docan-supplied "thin doubles" above my magnificent "fat singles", the combination is probably good for about 200A (see photo).
When you do assemble your battery pack, these "welded post assemblies" can handle about 3x the torque of the traditional "threaded into the cell" flat terminals. I read that they're rated for 81 inch-pounds, and I cranked mine up to almost 70. Take note that the provided posts accept a hex wrench at one end, you will want to use a tiny hex head in your mini-torque wrench to crank in the posts first (before adding your bus bars and balancing lead ring terminal, or your battery cable connections on the end ones).
The flat contact area of the "welded post assembly", at the top of the cylinder, is very small. The long cut-outs within the Docan-provided bus bars further reduce that area, by a lot. You should apply high torque, to improve the electrical conductivity between the first bus bar and the top of the assembly cylinder. A washer, if you can find or cut one of the right size, might also help a bit.
My own battery pack will be pretty heavily compressed, reducing the movement of cells via expansion and compression. My heavy-duty, non-bent bars should do fine. That's it in the photo, underneath the Docan "pair" and about 50% thicker than both Docans combined.