2010 Avalanche adding 2nd battery question

[mikeyr114 1]

Hey guys, I have a 2010 Avalanche, and looking to add a 2nd battery. I have the Blue sea dual batt switch with VSR. Currently there is only 1 battery installed with all wires connected to the one battery. It appears all I have to do is add a 2nd battery and connect the acc hot and acc ground leads to the new battery? Should I jump the neutrals as well? If you need pics let me know. 

[Wylie_Tunes 146]

2 hours ago, mikeyr114 said:

It appears all I have to do is add a 2nd battery and connect the acc hot and acc ground leads to the new battery?

Much more involved then this. No loads, but the auto bilge, are wired battery direct, so everything goes through the switch. You will need to determine which loads, currently on the existing battery B+, are house and which are for making the boat go. Then you will wire them to the appropriate terminals on the switch. 

2 hours ago, mikeyr114 said:

Should I jump the neutrals as well?

Without the new bank connected to the existing bank, it will not be part of the electrical loop. Battery will quickly go dead.  

[mikeyr114 1]

Here is the pic. I purchased the boat this summer and just thinking the previous owner put both leads to one battery instead of replacing both. Everything I see indicates it was originally set up for dual batteries. 

[Wylie_Tunes 146]

Oh, ok, so the switch and VSR are already installed, but the 2nd battery was removed. I dealt with this same scenario last month, just older boat.

lets presume that everything on the back of the switch is correct. In this case, you just need to figure out witch B+ cable is connect to the house side of the switch and which is connected to the main cranking side. Then move the appropriate cable to the new battery. 

[mikeyr114 1]

Ok sounds good. I will check and see tomorrow. Thanks. 

[mikeyr114 1]

So just checked out the boat. There are 2 wires connected to the pos. battery post; One is unlabeled and a size 0 awg (or close) wire and the other is a 6awg wire that is labeled acc 2 batt 2. Both go into the black switch box mounted on the wall. The negative battery post has the following; one size 0awg wire that goes into the bottom of the boat - guessing a ground bar back to the engine, one 6awg wire that appears to head towards the starboard side of boat(guessing breaker panel area), a 4awg wire to ground the amp and 2 smaller ground wires. 

I am thinking that if I take both 6awg wires and add those to the 2nd battery that is the way it was from factory? What are your thoughts? Is there a need to then jump the grounds as well?

So I have an understanding of how to operate once this is done, I run the boat all the time in the on position and then if the battery is dead on the water (from radio )I would then switch to combine? The auto bilge bypasses the switch correct and is always powered as long as battery is hooked up?

Thanks for you help! I am looking to swap out the factory MB quart radio this winter and wanted to figure out the battery system first. 

[Wylie_Tunes 146]

3 hours ago, mikeyr114 said:

I am thinking that if I take both 6awg wires and add those to the 2nd battery that is the way it was from factory? What are your thoughts? Is there a need to then jump the grounds as well?

You must connect the new battery to the ground circuit, or its not part of the loop, and the alternator will never charge it. That 6ga ground is supply from the battery for the helm, not a ground to the battery. Sounds like they tossed the house bank ground cable. 

3 hours ago, mikeyr114 said:

and then if the battery is dead on the water (from radio )

If everything is wired correctly, nothing will draw from the main cranking bank when engine is off, so audio should never run the main down. 

Get in boat, turn to on, leave boat, turn to off. 

[mikeyr114 1]

perfect so both positive and negative 6 awg to the new battery and jump the grounds from battery to battery?