40kWh battery bank - batteries in parallel

[ArranP]

My boats DC electrical is 24V nominal and I'm planning to install a 40kWh battery bank.

The battery supplier ( China black box with built in BMS ) has dis-couraged me from connecting any more than 2 batteries in parallel. I have been using their batteries ( 2 in parallel ) for years in my land based home off-grid 48V system.

The maximum concurrent load on the boat is anywhere from 300A to 700A @ 24V.

I am considering 4 batteries in parallel, each with its own 200A BMS and MCB ( would adding a fuse in addition or instead of the MCB be a good idea ? ). Connection options are "Config A" be made post to post with each opposite ends connected to the bus bar, or "Config B" each the battery be connected directly to the busbar.



Cabling; 4AWG cable is easier to find than 2/0AWG, are there any drawbacks to using 2x 4AWG cables in place of 1x 2/0AWG cable ?

Any better ideas welcome and thanks in advance for your feedback.