Really nice battery build! Maybe you've already answered this, but with the solid buss bars and a set-up to allow expansion between the cells, isn't that an issue?
OK, I've started when damn well better be the final version of the battery ?
Two separate packs of 16 cells (remember this is a 2p16s battery - so each pack is actually 2 in parallel, 4 in series). Sitting on top of the same plywood ends with angle bracket and rubber feet. I've added 1 more rubber foot to each end. Spanning the length is two 1"x2" t-slot aluminum. Surprisingly strong - I'm getting almost no flex with the 16 cells on top of it. Those will "float" on top of the angle bracket, allowing for the cells to "breathe".
I'll be using the same 1/4" by 1" solid copper bar between everything. 4-5 shaped pieces of 3/4" by 1/16" copper bar from the end cells to their endpoints (breaker, relay, and interconnect terminals).
I've moved up to 3/8" threaded rod and will use 6 per pack instead of 4. The threaded rod is also medium strength (70,000 PSI instead of 40,000). This should give me extremely high strength and consistency. As a result of going with 16s AND increasing from 4 to 6 rods, I've ordered new springs (due tomorrow).
I intend to drill & tap small holes into the bus bars and connect the BMS leads to that instead of using the cell terminal connections. This will keep everything else off the terminal -- that way a serrated nut will directly contact and dig into the bus bar and provide a nice durable vibration-resistant connection.
I've sacrificed the ability to move the pack (too heavy now) for less AC ripple. But since this is a much easier pack to build (mostly due to single 4-terminal bus bars for everything), I'm OK with that. I'll have to disassemble and reassemble one more time.
Awesome! Are you planning to insulate the bottom of the cells from the aluminum rails when you install in your RV?
Great video! Thanks for putting this together. This could be very helpful in the repair of the crooked threads in my recently acquired Lishen 272ah cells. [thread link]I repaired one of my cell's threads:
Great video! Thanks for putting this together. This could be very helpful in the repair of the crooked threads in my recently acquired Lishen 272ah cells. [thread link]
It would appear that you didn't break the tang off of the helicoil after it was inserted - was that to avoid damaging the terminal? Seems like you'd gain another thread of engagement, but maybe not worth the risk? Am I correct in the assumption that you didn't break it?
-uberpixel
I guess if you’re getting adequate torque maybe no need to poke the bear? Those short helicoils look like they could do the trick for my repair without too much grief. Just not sure if the M7 tap will be large enough to cut away and correct the off axis direction that my holes were tapped.I didn't break it off. I was being lazy. I'll try to break it off and see what the difference is.
I guess if you’re getting adequate torque maybe no need to poke the bear? Those short helicoils look like they could do the trick for my repair without too much grief. Just not sure if the M7 tap will be large enough to cut away and correct the off axis direction that my holes were tapped.
Let us know if you try breaking tangs off and how it goes.
-uberpixel
Let us know if you try breaking tangs off and how it goes.
Well, that explains why I didn’t see any in the bottom of the hole when I paused your video. I must have watched that part 5 times to figure out what you did.I don't have any tangs apparently. I'm not sure if I broke them off during installation by twisting the installation tool hard or if they got sort of shoved out of the way with the beveled edge of the stud. I'm getting 4.5 - 5 turns.
Well, that explains why I didn’t see any in the bottom of the hole when I paused your video. I must have watched that part 5 times to figure out what you did.
I think the intention is that you hit the tang with a punch and then remove it from the bottom of the hole. Without knowing how much precious aluminum is left at the bottom of the hole that part scares me. There’s a video online of a guy just bending the tang back and forth with a small screwdriver. Maybe it’s unnecessary?
I guess for now it will just have to be the mystery of the missing tangs.
-uberpixel