Copper spacer between diy battery packs


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Rasmusm88

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Mar 2, 2022
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Hi all :)

I have a question regarding size of a copper spacer between the positive and negative terminals on my 14S200P battery packs.

Reason for asking is I have access to copper 15x15mm or in inches its 0.59"x0.59" in what ever length and can make it my self (cnc worker) planning to make em 2cm wide / 0.78" and a 10mm/0.39" hole through it, since my cable lugs are 50mm2 lugs with 10mm hole in it. I could probably go 8mm/0.31" center hole aswell.

But question is, is that too flimsy for 100a load from battery, will rarely see that much is my guess, but better safe than sorry?

Here is a picture of what I'm thinking -

What do you think?
 

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Rasmusm88

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So according to my own calculation, 15x15mm=225mm2 minus the center hole r2*r2 x Pi so 5x5 * 3.14 = 78.5mm2 minus 225mm2 = 146.5mm2 copper from that block is this wrong ? And I guess 50mm2 is enough to carry 100a @ 48v. So my copper spacer is a succes hehe
 

Rasmusm88

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They go inbetween these, just to make some space between the packs :)

Oh and I see the picture is gone will edit it
 

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OffGridInTheCity

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They go inbetween these, just to make some space between the packs :)

Oh and I see the picture is gone will edit it
Thanks for the clarification/pic. How many amps do you expect?
Perhaps saw off 1/4" copper pipe sections as 'spacers' (or use a stack of washers) and fasten inbetween with bolt/nut - the bolt will carry current as well.
 

floydR

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On a separate Note is the bar the battery pack is on metal? Perhaps add some insulation at the bottom of the connections. Looks like a short could happen quite easily.
Later floyd
 

Rasmusm88

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True about the bolt will carry current aswell, didn't think about that hehe ..... do you think my calculations are correct for that copper spacer? My multiplus II 48/5000 will do 4000w continuous, so at nominel 51.8v it's 77Amps. But can peak at 9kw for seconds

Hi Floyd, great point but picture is temporary location for storing it :) still in progress of finishing up my shed. And permissions for the installation.
 
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