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Discussion Starter · #1 ·
Series first then parallel? Or vice versa?

Ok I am designing my battery pack. - 144 volt / 150 ah

20 modules - 14.4 volt/75 ah each module

I could wire the pack as follows:

Option 1: 10 modules in series giving me 144 volts plus another 10 modules in series giving me 144 volts

Then connect the 2 144v packs in parallel for 150ah

So I think that would be written 10s2p ?

Option 2

Wire the modules in parallel in sets of 2 giving me 14.4 v/150 ah each set of 2
Connect the 10 sets of 2 in series to give me my 144 v/150ah pack.

2p10s?

Is there any advantage or preference of one way or the other? Is one more efficient?

Cheers!
 

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Discussion Starter · #6 ·
I would connect each pack in parallel with another, and then connect those twin packs in series.

So, not just the 2 ends of the 10s string, the 2 ends and the 9 pairs of internal wires too.
So would this be Option 1?

I have the pos and neg ends of the 10s string, got that, that is the end of the pack. Sorry I don't understand, what would I do with the other 9 pairs?
 

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Discussion Starter · #8 ·
The modules are almost brand new. They came from a wrecked VW Egolf with less than 8000 km.

I kind of like the idea of 2 separate 144v packs that are connected in parallel. It might be easier for maintenance . Also if a problem occurs in one pack I can disconnect it and at least keep the truck running with the other pack temporarily.

However from my research it seems like lithium batts should have parallel connections made first then series.

I got this from Battery University:

"With Li-ion, the parallel strings are always made first; the completed parallel units are then placed in series. Li-ion is a voltage based system that lends itself well for parallel formation. Combining several cells into a parallel and then adding the units serially reduces complexity in terms of voltages control for pack protection."

And apparently charging the packs will be uneven with Option 1?

What complicates things in my mind is the modules are already a mix of series parallel (Each module contain 12 x 25AH cells in a 4S3P configuration) so does it matter what I do after that?
 

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Discussion Starter · #9 ·
I would connect each pack in parallel with another, and then connect those twin packs in series.

So, not just the 2 ends of the 10s string, the 2 ends and the 9 pairs of internal wires too.
Just reread your post. Just to clarify I think you are saying each module in parallel then in series. In other words Option 2, correct?
 
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