Wanted to share my experience with Lithium batteries. The boat in my siggy has a Ghost TM and my battery setup is (3) Ionic 50 AH batteries for the TM and just recently a 125AH for the cranking battery. I had this week off week and fished every day which was awesome btw. After a day of fishing for me Tuesday, my batteries showed 84% power left. I fished Wednesday also before charging and was still at 72%. I charged them Wed night and fished yesterday and today and by the end of today, I was at 76%. Now I'm fishing lakes, not current, but I'm blown away with how long I can go between charges. Without a doubt I could fish 3 full days w/o needing to charge. I run a Noco genius charger and easily these are the best batteries I've ever used.
My Ghost being brushless is easier on batteries but still I'm beyond impressed with the 50AH batteries. If you're on the fence between 50 and 100AH batteries, in my experience 50AH is all you need.