I have a 10HP 24V Sidepower bow thruster. It is powered by 2x 4D 12V batteries housed close to the thruster and wired via a Sleipner Sidepower combiner arrangement. Batteries are charged with a dual output 2x 15 amp charger. You should consider the current
load before you relocated batteries away from the thruster. I was impressed to find out that my unit is rated at 340 amps!!!
(as is my stern thruster).