Post 10

Charger

Stereo

The one in the forefront is the port motor the one to the left behind it is the starboard motor the one to the right behind it is the house battery

Just a different view

Since I can parallel them from the switch do I even need to parallel any of the batteries at all or parallel all three of them what's your advice

You can parallel as many bats as you like, the draw back is IF (big if) one of them has an issue, they all can be taken down by the bad one. If there happens to be a dead short, then there are all those other bats providing more heat and power to ground. Some put fuses between large banks just to protect against this.

With your setup I would connect the house with the stereo, unless you have things on the boat that you don't want to go dead like the fridge. Now if even when using the stereo if it doesn't kill the bats, then your still good

No, unless you need more power then your getting now

Comment on stereo bats
The cables attached to the bats are to large (thick) for the post. It looks like the nuts only have about have their thread being used

Your boat was designed to parallel the house and port battery by Formula. They figure if port doesn't start, you can start the starboard and then get the port started from the ALT off the starboard.

Edit: and your charger is a 3 bank,

That is correct the three bank charger I believe it connects the two engines or charges to two engines and the stereo batteries there is no connection or lead to the house battery to keep it charged

You have 4 banks now,
port and house
starboard
Gen
Stereo

Maybe there is a ACR somewhere

What's an ace may I ask I will look for it

ACR is automatic charge relay, like this Blue Sea model
https://www.bluesea.com/products/761...12_24V_DC_120A

I connects between one of the banks and connects automatically once charging starts. It comes down to which bank is not being charged directly by Bat charger? Could be the Gen charges the Gen bat only when its running. That will work so log as it gets used, otherwise it will discharge far enough someday and go dead