What size lithium to run all electronics and black box?

Thanks for the help !!

125AH Ionic is our go to we sell our customers for cranking as well as to run dedicated electronics. Less mess running 1 house battery than multiple with a funky charger setup, and plenty of size to do all.
But, 50AH Ionic is enough to just run electronics for customers who insist on a dedicated battery to just do their electronics.
Let me know if I can help.

If you're already talking lithium, then you need to decide between NMC and LiFePO4 chemistries. Most boat (non-ice fishing, non-Kayak) applications sway toward LiFePO4.

"Which Electronics?" and "for how long?" are the next two questions. There is a spreadsheet that can be downloaded, link in the video description, where you can plug in your electronics setup and compare different run times.

Ionic 125ah 12 V is also starting battery

I've been looking at all this too because my lead acid trolling motor batteries are starting to show signs they are about to give up, they'll still fully charge but by the end of a day of steady use I'm running on high just to get around. I've looked at the Ionic's but took a gander at Dakota Lithium's website yesterday and they offer pretty much the same deals. It will come down to who has the features and then I my not buy either of these brands if I can find a better deal with the same quality these two brands are known for, I'll have to do something before summer gets here I'm sure.