Browneye,
I just ordered four Eve 280Ah prismatic cells (with the aluminum cases) and need to build a 4s1p box like yours. What you have done looks great to me.
1. If you had it to do over, would you use both the thin cutting boards and VHB tape between your cells, or just the cutting board?.
2. Where did you source, and what is the material you used to build your compression box?
3. Did you use a torque wrench to tighten the nuts on the end of your threaded rod, and if so, how many pound of torque did you apply?
Thank you for your help!
I would use just the cutting boards. The foam tape is fine, but they really stick. It seems like you could cut them apart with a piece of fishing line, but I tried that on another component and it was pretty tough going.
Once you apply a little pressure with the compression rods - don't over do it - they're not going anywhere anyway. I just snugged them down a bit, not too tight. This isn't the place to wrench them down hard - you're looking for about 12psi compression on the cells. It's more of a fixture to HOLD them, to keep them from puffing, not to squeeze them hard.
With the cutting board material you could disassemble easily to replace a bad cell or rearrange them for troubleshooting.
I got surplus StarBoard from Paragon Plastics in Santa Ana, CA. I don't know if they ship or not. But there are some amazon sellers that have cut panels at a reasonable cost as well. Various colors too. I may well have used gray plastic had they had some on hand. It cuts and shapes just like wood. But you must know that melting point is about 275* F, whereas plywood is good to about twice that before it burns. I don't plan on having any fires in my rig. LOL Also be careful with screws into starboard - it does not have the holding power of plywood. And if you screw down lexan like I did, most craftsman will recommend a buttonhead screw without a countersunk screw and hole - this latter cracks much easier. Lexan is about five times stronger than acrylic though.
After the pack was built I was informed that bare copper lugs on aluminum was a bad combination for galvanic corrosion. So I replaced the main leads with tinned copper terminals. And I tapped the bus bars for the bms sensor leads instead of putting the ring terminals under the nuts. Also sourced exact fitting aluminum washers to increase the contact area under the bus bars, that thread is here, my posts start about #188. Member
@triplethreat may be able to sell you a handful of them - he bought a box of fifty from McMasterCarr:
If you are getting up to 200amps then it might be worth it if done right. Have you just got 4 cells in series? 8 cells, running 24V system with inverter, but 200A would be really really pushing it. In an RV/offroad truck, btw.
diysolarforum.com
I did not use a torque wrench on the studs, but I have a lifetime of turning wrenches and a good feel. I was going to buy one, but they were $40 and I figured I would use it once, and the spaced it out, and when reassembling I still didn't have one on hand. So by feel. I do recommend you got an inch-pounds torque wrench to ensure you get them tight enough without stripping or breaking the studs. Plenty of horror stories around here with ruined cells.
Actually, one of my cells came with the terminal un-tapped. That's, right, no threads. But I've tapped enough thread holes and I had a M8 I could grind down (the hole is shallow) and got it tapped to install the SS grub screw - locktited it in and marked it.
If you overtighten you'll pull the aluminum threads right out of the socket.
Otherwise I'm thrilled with the way it turned out, and it's working exceedingly well.