The house loads are minimal on my boat. There is a depth sounder, and a radio, and perhaps some running lights if it's nighttime. The 35amp alternator can handle that load fine.
Once engine is shut off, I'll switch the house loads to the Lithium.
This is standard (if a bit prone to forgetting) setup on old boats. I'm not interested in rewiring a bunch of stuff. Just trying to make sure that by hardwiring the alternator to the AGM starting battery only, even if I choose to start the boat in an emergency with the Lithium bank, the alternator will not be charging the Lithium bank. It will be charging the AGM
Because normally the alternator on old boats charges back through the starter and back into whichever battery that was used to start the engine. I want to avoid that.
Specifically I wanted to see if my drawing had any red flags, for instance, I believe I don't need to rewire the alternator negative, as that goes back to the common ground (engine). Just rewiring the positive, I believe.