Same parallel/serial connections but a bit different layout

[deeperblue]

Hi,
I am planning to DIY 4 lithium 12V batteries, and then either make a 24V battery bank or a 48V battery bank. Each battery will be assembled the same way (everything being the same).
Due to space limitations, I am considering install the batteries in two locations close to each other, like the diagram below. Are there going to be serios concerns? I guess it is best to make the corresponding cables the same length? (i.e. in 24V configuration, it is best to use the same length cable connecting the two 12Vs for both 24V combination), so that from electronics point of view, the two 24Vs are actually identical? Or if the cable is large enough, some reasonable length difference would not matter much?

Thanks!

 

[sunshine_eggo]

Hi,
I am planning to DIY 4 lithium 12V batteries, and then either make a 24V battery bank or a 48V battery bank. Each battery will be assembled the same way (everything being the same).
Due to space limitations, I am considering install the batteries in two locations close to each other, like the diagram below. Are there going to be serios concerns? I guess it is best to make the corresponding cables the same length? (i.e. in 24V configuration, it is best to use the same length cable connecting the two 12Vs for both 24V combination), so that from electronics point of view, the two 24Vs are actually identical? Or if the cable is large enough, some reasonable length difference would not matter much?

Thanks!

You've misidentified your primary (+) and (-) on the lower left battery. You will only have 6.4V between those terminals.



In the 24V config, #1 + #2 length must equal #3 + #4 length.

In the 48V config, you want the green wire connecting the two 8S strings to be beefy as hell and as short as possible.

Obviously, it would make more sense to rotate the lower left battery 180° to bring the terminals closer to their respective connections.