Blake

Lets assume you leave everything the way it is.

Problem you might see is Noise in your stereo when the boat runs.

After you listen for a few hours at the party cove the boat wont crank and you have defeated the purpose of a second battery.

This is what i would change if my thinking if i was you.

1 No problem with Deck staying on battery 1 as its wired threw the main boat harness to the fuse panel and thats a good thing. What you need to change is just the ground line off the deck. Find the black ground wire and extend it and connect it directly to the Negative terminal of battery 2.

2 Never run both battery in the All position if you are going to have the engine off for any extended time. In effect what you have is a huge 12v single battery when its in the ALL position. This is when you switch the selector to 2. 2 is where all the stereo Amps are plugged into. This is the stereo or Aux battery. This way when you are party coving and listening to music you are only draining the Aux battery. Now if you kill the battery then you switch the selector to 1 and crank the boat up. Once the boat is running for a minute or two or you are driving it then set the selector to All to charge both batteries.

Never Never put the selector to All if you think 1 battey is dead as this Equalized both batteries and you may have 2 dead batteries now. Also try to refrain from the temptation to start the boat and then switch to 2 and send all your alternator charging to your dead battery as this can over load the alternator and in time burn it out as well. The dead battery will be like a starving child screaming for voltage and the alternator will act like a man just rolling out of bed before coffee.

I run a 3 battery setup currently and when the boat is cruising we always have it in All.

When we stop we change it to 2

When we start going again we change it to 1 to start it, then All while driving.

When i get home i check all the batteries with a charger.

This also brings up the question how do you home charge it? Put the selector in All or Both and connect the charger to any battery you like as it will see it as 1 big 12v battery and charge them both at the same time.