Battery for Electronics only Question

[jdmidwest]

I am just thinking the original op does not have a kayak, otherwise, why would he need a cranking battery? Or 2 batteries for that matter. But that has not been brought out in the open.

I run a cranking battery on the bass boat and another deep cycle AGM for the electronics and trolling motor. That way, if I suck the life out of the trolling battery, I can still start the gas motor without having to dig the pull rope out of the emergency box.

I have a portable fish finder that has 8 AA battery pack that gives it 12 volts. It will run for at least a day or more on that system. B/W fishfinders are low voltage consumers. Bigger ones that have down scan have more draw.