Primarily adding pictures and details for the evential resource, but, as always, welcome any critique and advice.
I've gone with lithium batteries, largely for weight saving but also because I think it is a better solution for the deep cell electronics and trolling motor battery (and didn't want to mix types). I went with Group 31 size for both so I could swap out to lead acid should I decide, but the weight savings is significant. The lithium starter battery is about 33 pounds and the deep cell about 22 pounds - vs lead acide group 31 batteries at 65-70 pounds each. Both batteries have BT for monitoring on my phone, and starter battery has self-heating that cuts on at 14° (and then turns off when internal temp hits 50°).
The starter battery sits just in front of the port side rear flotation chamber, between 2 bulkheads. Cabling is such that I can pull the battery out and then disconnect where I have easier access - 1 pos cable to my switch, 1 neg cable to the HD bus you see above it. The motor will connect to the switch and the Neg bus.
The switch (Blue Sea 6011 - turns both circuits on but keeps them isolated - with an option to combine if needed) is mounted on the bulkhead in front of the starter battery, and my main switch and fuse panel box will be just fore of that on the shelf. Tucked in behind that on the bulkhead is the Yandina Combiner.
A better picture of the Yandina (now SmartShore) Combiner. It is tucked back as I don't really need to be able to see it or have much access to it, other than to periodically see the lights to check its status. This is a great little device that senses when either battery has reached full charge (by sensing voltage > a certain amount) and then passing the charging current to the second battery. Ie., when the motor is running and alternator is sending a charge, and the starter battery is full, it passes the charge to the house battery - and, in reverse, when using a charger on the house battery and it us full, the charge passes to the starter battery.
