I can understand wanting to run on separate battery but going to throw this out there. I run my livescope, 93 and 102 on my group 31 cranking battery. Run my livewell and radio all day. Have never seen below 12.2 volts and fish all day. Might be my style of fishing allowing me to do this as I’m constantly running and gunning instead of just sitting and running livescope. Constantly charging with big motor while going to next spot.