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You are correct, with both switches on #1, both motors are drawing from one of my banks (2 blue tops), and yes both motors have alternators that are pumping 13.9 volts on the system. And I guess if I'm on #1 position on both switches being that my amp is connected to #1 also I have it running too.

How would I separate the house system(amps and fridge)? Also what about charging, should the alternators really only charge the starter batteries? And lastly, are my blue tops ok for motors?

I have 3 batteries.
1 for each engine and one as a house battery to run stereo. The stereo battery is a deep cycle , the others are starting commercial batteries.

The "house battery" (stereo) is on a charging relay/isolator to prevent any issues with charging, or starting issues. I can run the house battery down and still able to start

I got this recipe here and it`s been working perfectly


https://www.bluesea.com/products/761...12_24V_DC_120A

p.s. I find Optimas to be complete garbage.

and

I have twin engine 496HO and yes each motor has an alternator. What does ":Optima Bats are carp IMO" mean. Sorry, I am new to power boating and trying to learn all the terms.

" optima batteries are crap ...In my oipinion "


Runs 3 amps , no issues

I have 2 large amps, one of which draws about 30amps and other will draw less that 10. What do you suggest I do with wiring system? I have 2 switches that have busswork connecting both post #1's together and both #2 post together. The on-board charging system is a 10amp charger that is designed to charge 2 batteries at the same time and this is wired up to each post (one on both post#1 and other on both post#2)

Carp was a mistype. Crap was what he tried to type.
IMO = In my opinion.

I would isolate your house loads from your engine/drive loads and install a Blue Seas ACR.

Starting battery for engine. Deep cycle battery for house load (your amps, fridge, etc).

The link that ICDEDPPL posted is what your looking for.

More specifically, if you actually need 2 house batteries, I would purchase 2 of these....
https://www.bluesea.com/products/765...ery_Kit_-_120A

They are very simple to install and prevent any drain on your engine starting batteries from house loads.

I made a long post, but system crashed and didn't go through - I'll cut to the chase. Buy 2 of these, isolate your house load from your engine/drive load. All house loads should go to a house battery.
https://www.bluesea.com/products/765...ery_Kit_-_120A

This diagram from their page might help , I've been running a combiner for years with no issues although man they have evolved price wise .https://www.bluesea.com/products/761...12_24V_DC_120A