Dual Batteries

[Reserector]

I did my dual battery mod. This will give me peace of mind when I am scouting in the middle of nowhere.

I have had the switch for some time. My father bought it for the motorhome, but never used it. I finally found the perfect use for it.
I would like to have installed twin Optimas, but funds are low.

I cut , hammered drilled and welded the new battery tray from a single piece of sheet steel.
I dimpled two of the bolt holes with a ball peen hammer to keep the bolt heads away from the battery's shell. All edges were smoothed to prevent chafing of nearby harnesses.
I added a ridge made of rod to the tray to allow for the use of a GM battery clamp set-up. I was not able to find the plastic block used on GMs, so I picked up a conventional tie-down kit and used it instead.

The tray is bolted in to allow access to the harness that runs underneath it.

Last, but not least, the switch controls the GROUND connections instead of the positive connections. I actually read the instructions and diagrams, threw them aside and did it my way.
It is so much safer to run ground cables all over the place and keep positive cables short and direct.
The alternator wire still runs to battery one, as always. Battery 1 has a positive jumper to battery 2, so the alternator is essentially connected to both at all times. However, only the battery with a ground connection will charge. It may seem backwards, but think about it; it still breaks the circuit.

Here are the pics:

The finished tray


The location.


The tray, bolted in place.


The switch.







The completed installation:

[balage]

nIce install!

[Shift_Avenger]

Very clean install, it looks like it belongs

[LilRedExpress]

But if you are only charging one battery, what good is the second one; will it not be dead when you finally go to use it? I might be missing something fundamental about 12 volt power systems, so please make me understand why you have it set up this way.

Thanks.

[eglaisi]

Have you thought of adding an inverter so you can have 120V AC when offroading? This is my next project.

[Reserector]

It is designed to be a redudnant system. It is designed to be a redudnant system. This was done primarily for reliability. I often find myself in the middle of nowhere with no cell service, so my truck MUST be reliable.
I only operate one battery at a time, with the possible exception of winching, where I might select "BOTH". That means normal running and charging of one battery . The other battery just sits there just as if it were on a shelf in the store. I intend to switch from one battery to the other on occasion to keep them both topped up.

And yes, I do intend to add an inverter for when I am camping. Connected to one battery only, I will have one full battery for starting.

[mdawg4x4]

Res, you copied that from another forum I was on. Looks good.

[carphreak]

so let me get this straight, the system charges whichever battery you choose the selector to? brilliant!

[mdawg4x4]

What about the both selection. Is the alternator capable of charging both?

[Reserector]

Probably so. It is a 94 amp GM alternator. It was a bit of an upgrade from the 60 amp Nissan alternator.
I made it fit.