Cable/fuse sizing questions.

[Liam M]

I'm planning a 24v 2s2p battery (4 12v 100AH lfp + battery balancer) to 24v 3200W inverter (3 ft from battery bank).
Calculating for max load: 3200 / .85 / 20 = 188 amps - according to Blue Sea Ampacity Chart (single conductors/open air) 2/0 105c copper conductors should suffice?
Assuming this is correct, how to size interconnecting conductors for both series and parallel?
Do amps get split in some way for current sharing, or should all conductors be of equal ampacity based on the total max load?

Additionally, for fusing I am assuming a 250a Blue Sea Fuse Block Terminal MRBF at the main positive of the 2s2p bank?
What should the fuse size be for the positive terminal of the parallel connection?
Should the series connected positives get fuses as well?

 

[FilterGuy]

I'm planning a 24v 2s2p battery (4 12v 100AH lfp + battery balancer) to 24v 3200W inverter (3 ft from battery bank).
Calculating for max load: 3200 / .85 / 20 = 188 amps

I usually use 24V for the low-end voltage but the 20V is more conservative. 85% efficiency seems low, but I don't know the inverter so it may be correct.

However, there is one more step. The fuse should be rated for 1.25% of max rated load or 188 x 1.25 = 235A. You will need to round that up to 250A for an available fuse and the wire should be rated for 250A. (Yes this is being very conservative). Using ABYC recomendations you would need 2/0 wire.

If you used 24V for the low end we ger (3200/.85/24) x 1.25 = 196A. This would require a 200A fuse and 200A rated wire. Using ABYC you could use 1/0 This is less conservative, but I would be comfortable with it.

Note ABYC is far less conservative than the NEC. NEC would require a much larger wire.

 

[Liam M]

Thanks for the reply.
I’ve been searching through threads and a recurring recommendation seems to be to lean on the conservative side, which I am fine with.

Regarding fusing, should the parallel battery’s fuse be rated the same as main fuse?
And should all connecting wires be rated the same as the main wires?

 

[FilterGuy]

Thanks for the reply.
I’ve been searching through threads and a recurring recommendation seems to be to lean on the conservative side, which I am fine with.

Regarding fusing, should the parallel battery’s fuse be rated the same as main fuse?
And should all connecting wires be rated the same as the main wires?

Could you provide a diagram of what you are building.

 

[Liam M]

Could you provide a diagram of what you are building.

Based on this diagram, I will have 2/0awg wire from main positive/negative to busbars, with a 250a fuse at the main positive terminal (top right).
For the parallel positive fuse (lower right), is that sized for the amps of one 2S battery (100a) x 1.25 = 125a fuse?
And for the connecting wires, both series and parallel, are those all to be rated for each string @ 2awg, or for the total load at 2/0awg?