good stuff my man i just did a single 100ah battery in a box with a renogy 10amp controller and a 10w panel for a deer feeder. it runs a minnkota 40.
after 3 days of fishing ive decided im going to a 100w/5a panel like yours myself.
i took a marine battery and box, a renogy 10amp solar controller, a 10w solar panel off a gate or feeder, and a minnkota 40 trollingmotor and went rechargable.
i cant tell whats up but if its like a car go to vatozone and get a 72" brake line repair line it will have flare nuts on each end. get the size you need 5/16 or 3/8 or etc.
then go to harbor freight and get a pipe tube cutter and pipe flare tool and a tube bender.
then make whatever line you...
you never mentioned how you will charge these batteries. on a old mopar you could run a 10ga wire fused on BOTH ends 50amp fuse and go alt <> batt+.
dunno how that applies to you.
myself im gonna use a solar controller and panel to recharge.
there are wire size charts online. like your...