Is this 24V 2P4S Arrangement a Problem?

natec

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I'm looking to build a 2P8S 24V battery out of the EVE 280 cells. This geometry fits best in my van design. It seems like it should be fine, but I haven't seen it any any of the other designs on this forum which makes me think I'm missing something.

(if you are curious, the cells will be fixtured between two 1/16 aluminum plates with 15 members of 1/2ish inch all-thread preloaded with belleville washers to get the recommended 12psi) (also, the cell groups will be insulated with kapton tape)
 

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snoobler

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It's fine.

I recommend you double-bus bar the circled area. You have two series interconnects between all other cell groups, but only one here.

1612280836286.png

IMHO, 1/16" sheet is too thin. 1/8" should suffice.
 

natec

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Thanks for taking the time. I actually meant 3/16, but I'm happy to go with 1/8 if thats enough. I'm also planning to jump between those end terminals such that each cell has equal length to the other side and resistance is matched all the way along.
 

snoobler

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1/8 is thinner than 3/16, so stick with 3/16.

Simply adding a double bus-bar between the two cells circled will suffice.
 

HRTKD

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Since you commented on the plate thickness, I thought you might be interested: I did the math for 1/8 Al, 3/16 Al, and 1/2 plywood. I'll definitely be going with 3/16:

github.com/natecostello/van_two_point_oh/blob/master/electrical/battery/Battery_box_design.md#plate-thickness

Nice write-up. That makes me very comfortable with the 3/4" plywood end plates.

I tried to find a simple tool that would give me the deflection of a plate of aluminum that I was thinking of using for a table. What I could find was beyond my understanding, or it was behind a paywall.
 
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