I recently installed LVS34 with a Garmin106sv and after about a half day I would start motor the graphs would automatically turn off and then shortly after would get preset low voltage alarm. Cranking Battery is Optima Blue Top 18 months old with no prior issues. Also running a Helix 10 and 12 as well as elite 9. This was without running livewells.
Should I start turning console graphs off to conserve power or add a 5th battery?
What would be the recommended AH for lithium to run just the black box and Garmin?

I added a 54 amp hour lithium to run the box from = never had any problems. The battery is pretty small so I mounted it the rod locker.

tiltman on here has a napa store in wylie, carries the ionics.

50ah should run the 2 full day easy, voltage doesn't drop as it discharges like a flooded cell will.
I think they are about 350.00

100ah would probably handle all graphs/ls and take the pressure off the cranking battery.
around 700.00

or you can go whole hog and buy the 125ah but it is pricey at around 900.00. this one is also a cranking rated lithium and would do all your stuff easy.

ionics also come with bluetooth fwiw.