elongated bus bars

Wtavern

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Dec 8, 2020
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My new Eve 280 ah battery cells from Amy Wan have finally cleared customs and should be at my door tomorrow. I purchased 16 and confirmed that she only sent me 16 bus bars. I'm planning a 4p4s configuration for my bank and will be making my own bus bars out of copper bars purchased on Ebay. They're 1/8" thick and 3/4" wide. My question is if there's a problem with having long bus bars traversing 4 different cells, each approximately 11" long. My configuration will look something like this (picture found on internet, not mine):
IMG_0375.JPG

I was going to cut 8 bars to size and mark the top of the cell posts with a little marker and press the bar on top while they were still wet to see where I would need to drill the holes. I was also going to apply the protective shrink wrap in-between the holes. The only disadvantage I see is that this is for a mobile system that will see bumps and much more movement and the battery won't have maybe as much "flex" room to shift around, which may create stress on the posts (welded). However, they will be compressed and fixed to an an aluminum shelf as below. Any thoughts?

tempImageSCcgzx.png
 

Wtavern

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Dec 8, 2020
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Man that is some kinda slick cabinet you have there, strong, lightweight, very clever.
Appreciate the compliment! It took some doing to get everything to fit the space I had with the wheel well jutting into the middle of the space. I was lucky the multiplus with its new form factor and the eve cells fit so perfectly. Hardly an inch to spare in all directions!
 

HRTKD

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Apr 24, 2020
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I don't have a problem with your plan. Leave a small amount of wiggle/expansion room around the stud. I plan to create my own bus bars using aluminum and I won't be creating elongated holes, but I will slightly oversize the holes. For the balance leads, I'm going to drill and tap holes in the bus bars for them, separate from the terminal studs.

My cells are in a compression frame and they haven't moved at all, despite the rough roads my trailer travels over.
 

Stevelk

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Dec 12, 2019
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47
I don't have a problem with your plan. Leave a small amount of wiggle/expansion room around the stud. I plan to create my own bus bars using aluminum and I won't be creating elongated holes, but I will slightly oversize the holes. For the balance leads, I'm going to drill and tap holes in the bus bars for them, separate from the terminal studs.

My cells are in a compression frame and they haven't moved at all, despite the rough roads my trailer travels over.
Hi. I'm thinking aluminum for my bus bars too. can you give any info regarding how you decided size? I've heard 4x20mm, and and also 10x30mm.

Thanks

--
Steve
 

HRTKD

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Apr 24, 2020
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Somewhere South of Denver
Steve, I don't have my calculations written down. I started with the expected amp draw by my system. Let's call that 200 amps. I then found a table for copper bus bars that said what the cross section needed to be to support that amperage. I have two batteries so I could have cut the 200 amps in half, but I think I went with a larger number, say 150. Aluminum has about 55% of the conductivity of copper so the aluminum needed to have a larger cross section to make up for that 45% deficit.

That's more or less how I ended up ordering 0.375" x 1" Aluminum Rectangle Bar 6061-T6511-Extruded. As I recall, there's plenty of excess capacity in that thickness for my system.
 
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