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Dual Batteries - How does it work?

16K views 18 replies 11 participants last post by  J83 
#1 ·
I purchased my DMax in the summer. Now that winter is here, I was wondering about how the two batteries work? Are they simply interconnected or is one used for certain loads and the other for other functions? If I want to park the truck for several weeks, do I need 2 float chargers?

I guess I should pick up a "Haynes" for the electrical diagrams...
 
#2 ·
Wired in parallel, they're two halves of one large battery. Not two singles with different uses.

One float hooked to either will work, or a cig light/aux port plug-in with a solar panel to lay on the dash (if parked outside).
 
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#10 ·
There's logic in the ecm to keep the starter from engaging when the engine is running.
 
#15 ·
Reduce battery draw while in storage or in staging areas.
 
#17 ·
I would get out of the truck, close the door and not worry the batteries for even a month of sitting.
My spare 04 1500 (Old and Busted) sits for months at a time with an Interstate blem battery in it. Usually starts no problem. My 48 hp John Deere sits outside for months in the winter without running and starts fine.
 
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