Dual battery install...can't find answers

[Budbeater]

I have been searching the forum and I can't find any answers.

I am upgrading my 82 GMC Crew cab. Some of these trucks came with dual batteries. Mine did not. I did find, refurbish, and install the second battery tray. I have even plopped the second battery onto it. The problem is that I do not know how to correctly wire this sucker up.

I would like to do a stock type installation. I would really like to keep it simple as possible. Things just seem to work better and longer that way. This truck has the venerable 454 BBC between the fenders so while cranking is not an issue during the summer, winter can be potentially harder. I would like the extra CCAs and capacity without complexity.

Another issue is that the alternator seems just barely adequate for the truck. This vehicle looks like a christmas tree with all the marker lights. When I am pulling my 24' car hauler I have a hard time at idle if the lights are on due to the amp pull. That is without the heater/AC on or radio etc. I want to have enough juice to run everything if necessary. So, the next step is to install a more powerful alternator.

HOW DO I WIRE THE BATTERY? PROS AND CONS OF THE WAY YOU RECOMMEND?

Thanks

 

[Chevycrew]

I keep it very simple in our trucks, connect each battery to ground, and connect the 2 positive posts together (and to the alternator)

I use bigger than stock wire 4 gauge minimum, I also up the wire size from the alternator to the battery to 4 gauge as well.


Cons, If one battery is dead, they both are dead. Also if one battery fails it can drain the other.

Pros, double the cranking and reserve capacity, cheaper and easier


Ill let someone else get into the whole battery isolator switch wiring....

 

[Caleb]

You can buy an isolator from Napa (or most other parts stores I imagine) and that would prevent the draining issue. The isolators are usually quite cheap too...worth it IMO.

Oh, and the isolators come with the wiring directions/diagrams too.

 

[Budbeater]

Only one battery needs a connection to the alternator? That is what I am understanding. Is that right?

Other than that: 1. Seperately ground both batteries.
2. Connect the positive terminals of both batteries.

 

[spaggyroe]

Only one battery needs a connection to the alternator? That is what I am understanding. Is that right?

Other than that: 1. Seperately ground both batteries.
2. Connect the positive terminals of both batteries.

You could do that, and it would work, however you would be missing out on some of the advantages of carrying 2 batteries. When wired this way, a drain on the electrical system will kill both batteries. No bueno'

I'd personally go with an isolator as supergper suggested or get this bad boy from 12voltguy.com

http://12voltguy.com/web/index.php?...product_id=24&option=com_virtuemart&Itemid=43
(scroll down for product detail)