LML Battery Question

2004LB7

Super Moderator
Staff member
Dec 15, 2010
7,111
2,215
113
Norcal
Both batteries are wired in parallel so in theory share the same load. In practice wire length and resistance will unbalance this a little. The passenger side battery has shorter wires to the starter so would provide slightly more current then the driver side battery.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,677
1,947
113
Mid Michigan
Ever since the Dmax began in 01, the pass side battery up by the firewall has been considered the aux one. But like the guys said, if you're just hooking up accessories, it doesnt matter which one you use.
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
15,681
232
63
Fullerton CA
Correct way to hook up dual battery's.
 

Attachments

  • the-correct-way-to-connect-two-batteries-in-parallel.jpg
    the-correct-way-to-connect-two-batteries-in-parallel.jpg
    99.2 KB · Views: 78

gmduramax

Shits broke
Jun 12, 2008
4,081
252
83
Nor cal
Ever since the Dmax began in 01, the pass side battery up by the firewall has been considered the aux one. But like the guys said, if you're just hooking up accessories, it doesnt matter which one you use.

The NBS trucks the passenger side battery is hooked direct to the starter and alternator, there are ground and power cables on the same terminal going to the driver side battery. The cables are undersized in my opinion but the passenger side battery takes more of the load.
 

2004LB7

Super Moderator
Staff member
Dec 15, 2010
7,111
2,215
113
Norcal
Correct way to hook up dual battery's.

Yes! X2

I dont know how many times I've seen unbalanced loads and connections from not hooking it up like that. Even in plumbing, such as two water heaters the same rules apply
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,736
805
113
Texas!!!
Assuming this is for the 2015 listed in your signature, there is a junction block on the passenger's side battery with multiple cables coming off that feeds several high amperage circuits on the truck. One of those cables is the feed from the alternator. I would hook the lights up on that stud.