Bus bar sizing

[Gould]

I’m trying to match the ampacity of my bus bars with the fuse I have downstream (400 amp although unlikely I will ever get close to that draw) I went with 1/4” copper. I knew I’d have to shave about 1/16” for the nuts due to the length of the studs but should be fine.

Connecting everything got me thinking though. If expansion of these cells is such a concern why not use 4/0 cable to connect the terminals vs rigid copper?

 

[ereams65]

Lots of folks are using braided busbars already, so basically the same idea.

 

[Northernchateau]

The question you ask is the reason I will be using 1/4" closed cell foam between my batteries.
It will allow for irregular surfaces between the batteries, expansion, contraction and compression.

 

[Gould]

The question you ask is the reason I will be using 1/4" closed cell foam between my batteries.
It will allow for irregular surfaces between the batteries, expansion, contraction and compression.

Do you think you’ll still get the benefits of compression?

 

[Gould]

Lots of folks are using braided busbars already, so basically the same idea.

Good to hear. I may change my approach although what to do with the overpriced 3” pieces of copper.

 

[Northernchateau]

Do you think you’ll still get the benefits of compression?

Based on what I have read and videos I have seen it increases the cycle life of the batteries.
Being LifePo4 batteries are not cheap anything I can do to increase the life I am willing to try.
And yes I do as long as the foam is dense enough to handle the pressure.

 

[ereams65]

The foam isn't a bad idea, for sure. Every Automaker battery I've seen thus far have had plastic separaters between each cell that seem to have flexibility designed into them that allows for expansion/contractions. I'd think they would know most of what we're trying to learn. At least that's been the case in the Panasonic cells use in the Ford C-Max Energi and the Samsung SDI cells in the BMW.

 

[Gould]

I‘m planing on using 1/8” cork sheets between the cells to protect from accidental shorting, just a coincidence that it may also help with expansion