Two Batteries
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Mountain Pass
Joined: Apr 2015
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Two Batteries
My 79 F-350 Camper Special has 2 batteries, I think I may need to replace the batteries soon, do I need to buy 2 new batteries? What does the second battery do run the camper if I had one? Do I need 2 or can I just get one for the normal operation of the truck?
Gene
Gene
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 83
From: NorCal
Wired correctly, the alternator charges both with the ignition on and disconnects the main battery with the ignition off.
I installed two yellow-top Optimas.
Postmaster
Joined: Nov 2011
Posts: 2,553
Likes: 10
The second battery is there basically to provide power when the engine is not running for a camper or whatever... while saving one battery charged up for starting. If you don't need much power with engine "off" then you really don't "need" 2 batteries. One battery and a decent alternator will do it.
That said, keeping the originality of the 2 battery setup may have value/benefit... and also means it is not necessary to customize wiring.
That said, keeping the originality of the 2 battery setup may have value/benefit... and also means it is not necessary to customize wiring.
Cargo Master
Joined: Nov 2011
Posts: 3,354
Likes: 49
From: Great American SouthWest
The dual-battery solenoid that shipped with our trucks was a pretty good solution...forty years ago
The problem with the original is that when you turn the key, both batteries are tied together. If the auxiliary battery is dead, it will bring down the primary battery. Also, when it does start, the alternator will need to charge both batteries, putting a possibly substantial load on the alternator.
We now have the benefit of "smart" isolators, like the Cole Hersee Smart Isolator. This smart isolator:
1) Isolates the batteries to prevent primary battery drain
2) only charges the auxiliary battery after the primary battery is fully charged
3) can serve to allow the auxiliary battery to boost a weak main battery with proper cabling
I've installed Smart Solenoids in both my F-350s, and it's a great upgrade
Identical batteries are recommended for the factory style, but not necessary with the smart isolator
https://www.ford-trucks.com/forums/1...-the-77-a.html
The problem with the original is that when you turn the key, both batteries are tied together. If the auxiliary battery is dead, it will bring down the primary battery. Also, when it does start, the alternator will need to charge both batteries, putting a possibly substantial load on the alternator.
We now have the benefit of "smart" isolators, like the Cole Hersee Smart Isolator. This smart isolator:
1) Isolates the batteries to prevent primary battery drain
2) only charges the auxiliary battery after the primary battery is fully charged
3) can serve to allow the auxiliary battery to boost a weak main battery with proper cabling
I've installed Smart Solenoids in both my F-350s, and it's a great upgrade
Identical batteries are recommended for the factory style, but not necessary with the smart isolator
https://www.ford-trucks.com/forums/1...-the-77-a.html
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Greg5OH
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