I have a 12 and a 15 Solix, and 360 imaging (draws power too). They're power hungry and really cranky about low voltage... It has been a learning experience coming from 800 series humminbirds. The 31 AGM Duracell (link below) has done fine but even it won't hold up to both units on with full screen brightness and livewell pumps and PowerPoles all day. Knocking the screen brightness down to 7 or 8 makes a substantial difference in power use. I have also been putting the console unit on standby while fishing and I moved my PowerPoles over to one of the deep cycle batteries to take some of the load off of the cranking battery. This method worked fine in my last tournament, had no power issues all the way to weigh-in.
Also be sure to use this thickest gauge wire you can, my boat was pre-rigged with 10 gauge so there is not much voltage loss between the battery and the front unit. But, I think I'm going to have to run a separate set of wires directly from the 360 to the battery... it has been glitching and I suspect it is because I have it wired in with the front Solix's power wire. They're incredible units but they have been a pain in the [censored] rigging and figuring them out on my own. https://www.samsclub.com/sams/duracell-a.../prod3590232.ip