I have 6 GC batteries on Cbreeze, 4 midships and 2 in the bow. They are normally all connected in series/parallel. Bow thruster and windlass
tapped directly (with breaker/ fuses) from the fwd bank and inverter is 2' from the 4.
When I fire off the bow thruster it draws 200 amps from the fwd bank and 100 amps from the main. I am sure that after running the thruster there is a small voltage difference between the two banks. This voltage difference will cause a current to flow from the main bank to the fwd bank but in time as the voltage equalizes the current will go to near zero and all is well. When I run the inverter the reverse will happen. Been running it that way for 10 years.
Some that question this arrangement seem to not understand that as the current diminishes the voltage drop also diminishes (its called Ohms Law) even if the two banks are tied together with a piece of #22 gauge hook up wire. My main bank is wired with #1 AWG and the fwd bank is wired with #1/0. The interconnect is #2 fused at 150 amps on both ends.
Each set of batteries is individually switched. A couple of times a year I start my 3GM
from each bank starting with the bow set. I can't tell the difference in how fast it starts from each of the three sets even though the fwd bank has a lot more resistance in the circuit.