1999 Ford Super Duty 3rd Battery Install

RotorHead04

Observer
My appologies if this topic has been covered elsewhere on this site. I looked around but decided to start a new thread specifically asking for help in regards to my truck, a 1999 F-350 7.3L PSD. The truck comes factory with two batteries, I want to install a 3rd battery to run a power inverter for extra goodies while out on the trails and camping, and not worry about killing the main start batteries.
I would like a setup that allows the alternator to keep the extra battery charged, as well as the main batteries. Is it also possible to allow the 3rd battery to assist the main batteries in starting the truck if they somehow get low? How do you tell the power inverter to shut off if the extra battery voltage drops below a given level of charge, when the truck is not running? How do you tell the alternator which battery to charge while the truck is running? How do you install a volt gauge to monitor the level of charge for each battery? Forgive me if this makes no sense, or if its so simple your laughing. I don't speak electronics so I am at a loss. I managed to wire up some auxiliary driving lights to my bumper, when I flipped the switch and they came on I was dancing and shouting like I had won the lottery. That is the extent of my knowledge of things electrical. I have an extra truck battery, and an inverter and thought it would be really nice to combine the two on the truck. I just don't know the necessary black magic to make that happen. Elaborate, yet simple responses will be greatly appreiated.
 

Coscienceguy

Observer
The link provided above is how I built mine on my 7.3. However, even the nicer solenoid does not charge the battery that fast. For instance, it will not keep your third battery charged if you're drawing power over what's it can charge at. Do the set up he recommends, and it will be good, however, a future charging source like solar will be needed. THAT is the boat I am in this summer.

That being said, if you have any questions or want more pictures, check out my build, or message me. I am happy to help since I've been there before.
 

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