Currently I run my big motor, bilge and livewell pumps (that never get used), older lowrance unit, and new Helix 9 Mega unit all from my starting battery. I have 2 deep cycle batteries for the trolling motor. I don't have room for a 4th battery and I've been starting to have problems with my Helix 9 shutting off. I posted a question about it and was told my battery is not able to supply enough power for everything. I was told that because my big motor is a 1999 Mercury 175 EFI that I should not use an AGM battery (something about the stator). I would love to have lithium ion, but that's out of the question due to cost. What is a good battery that I could use as both a starting battery and a battery for my electronics?