Totally separate Dual battery systems.

Joined
Sep 27, 2004
Messages
38
Location
Burlington, Vermont
 
I've been doing some digging on dual battery set-ups, and am thinking about
totally separating my batteries.
I'm going to be adding another fuse block for accessories anyway, and with my Air compressor using the same belt as my existing alternator, I am thinking about just adding another alternator to charge the second battery. Does anyone see any huge drawbacks to going this route other than space ?

From my perspective Advantages are :
True battery redundancy (If the main power battery dies you switch the cables.)
True Alternator redundancy (If one alternator goes bad, I can just take the belt off the Air compressor and run just one alternator.)
No switches or diodes to add or go bad
I have another alternator sitting there begging to be used.
Systems are totally separate

Dis-Advantages:
Making it fit ( I think there is room.)
I barely have time to change the oil let alone add another battery and the accessories that require it !
How am I going to add a third alternator for the welder ?
I need some help here coming up with some more disadvantages..


I would love to hear your thoughts on this

Bill Atkinson
 
Joined
Aug 19, 2003
Messages
2,534
 
 
 
I need some help here coming up with some more disadvantages..
How to take advantage of the redundancy? Jumpers? In cab controls? How about TWO volt/ammeters? The advantage of having the batts connected but isolated means that you will never have to move the wiring for the engine and accessories wire harness to the other battery. Check the length of the lead to the fusible link... 'course, you could open the hood and physically move the batteries from tray to tray... why would you want do that?

2 alternators = more drag on the engine.

2 alternators = non standard belt system. Not a big deal, but a consideration.

Prolly some other stuff that I didn't list off the top of my head.

M
 
Joined
Sep 11, 2012
Messages
533
Location
Vancouver, B.C.
 
Anybody else here gone down this road? I would like to keep my starting battery totally separate from my house battery. Sometimes I leave the truck for a week at -25. I need no possible additional load on the start battery.
 
Joined
Dec 6, 2019
Messages
86
Location
MD,USA
Anybody else here gone down this road? I would like to keep my starting battery totally separate from my house battery. Sometimes I leave the truck for a week at -25. I need no possible additional load on the start battery.
I have a 2018 LC and I think this is what I will do, at least at first. I plan to have an Odyssey group 35 on Slee's mounting tray for the 2nd battery. The battery will just ride around unconnected to anything. If I need to charge it from my CTEK charger using shore power or my Goal Zero 1400 with solar panel I can. If I change my mind down the road and add a BCDC to charge the 2nd battery I can do that too.

EDIT: fixed a typo "ftom" to "from".
 
Last edited:
Joined
Sep 11, 2012
Messages
533
Location
Vancouver, B.C.
 
I'm always carrying a spare alternator, so I thought I might as well use it to charge the second battery. Gives me redundancy if I have alternator issues in the middle of nowhere, which I've had before. Most of the research I've done leads me to not totally trust the two battery systems. Sometimes I leave the truck sitting for 2 weeks when I'm out on the land, so it is potentially deadly to come back to a flat battery. Sometimes the truck sits far from a power source in -30 for a week, so I want to keep the starting battery as risk free as possible. I can set the second battery and alternator up physically with normal levels of problems, but I'm having trouble mimicking the wiring scheme. Wiring is not my strongest point. Eventually, I want to add solar panels and a controller, but first, I want the house battery to charge while I'm driving.
 

DickM

SILVER Star
Joined
Jan 13, 2009
Messages
795
Location
Gypsum, CO
 
 
I have a second alternator located in the factory smog pump location powering the completely independent second battery system with second fuse box located in the driver's kick panel. All "house" loads (fridge, stereo, lights, etc.) and winch are supplied by this battery. Second voltmeter in A pillar 3 gauge pod. This setup was done while the 2FE was being built, so everything was out of the truck and easy to add/modify.

The only drawback for me to this approach has been the inability to couple the systems at will. The optima house battery recently died, and since the relays for the upgraded H4 headlights were not powered, I had to jumper to the good battery to get headlights.

Overall, for me, the security of two independent systems offsets the negatives, as we travel solo often. When solar is added, it will be only on the house system.

Definitely a bit more work to go this route, but it made sense for my situation. There are a lot of options for isolation systems which would be more "plug and play", so that is a consideration.
 
Joined
Sep 11, 2012
Messages
533
Location
Vancouver, B.C.
 
I have a second alternator located in the factory smog pump location powering the completely independent second battery system with second fuse box located in the driver's kick panel. All "house" loads (fridge, stereo, lights, etc.) and winch are supplied by this battery. Second voltmeter in A pillar 3 gauge pod. This setup was done while the 2FE was being built, so everything was out of the truck and easy to add/modify.

The only drawback for me to this approach has been the inability to couple the systems at will. The optima house battery recently died, and since the relays for the upgraded H4 headlights were not powered, I had to jumper to the good battery to get headlights.

Overall, for me, the security of two independent systems offsets the negatives, as we travel solo often. When solar is added, it will be only on the house system.

Definitely a bit more work to go this route, but it made sense for my situation. There are a lot of options for isolation systems which would be more "plug and play", so that is a consideration.
Hi DickM, that sounds pretty much like what I'm trying to do. Any chance you could post a drawing of your wiring and fusing? I'm getting quite a bit of conflicting information and differences in wiring schematics. So far, I'm putting most of my fuses on the fender wall near the main fusebox. The charge warning circuit seems fairly tricky to duplicate, but that could be just because I'm not excellent at wiring.
 

DickM

SILVER Star
Joined
Jan 13, 2009
Messages
795
Location
Gypsum, CO
 
 
Any chance you could post a drawing of your wiring and fusing?
Sorry, no real overall schematic as the whole system has "evolved" as components are added /deleted / changed, and this is on a pretty non-stock 60 series as well. And you are right, search will give you a lot of different ways to "skin the cat". My approach general approach would be to break the project down into manageable pieces by drawing a basic diagram of the main components (alternator, battery, fuse bock, lights, stereo, etc. ) and figure out where to physically locate each one in the truck. Using distances and load requirements of each, you can figure wire sizes, and any fusing required for each branch of the tree you are building.
Good luck, and keep all the smoke in the wires.
 
Joined
Sep 11, 2012
Messages
533
Location
Vancouver, B.C.
 
Sorry, no real overall schematic as the whole system has "evolved" as components are added /deleted / changed, and this is on a pretty non-stock 60 series as well. And you are right, search will give you a lot of different ways to "skin the cat". My approach general approach would be to break the project down into manageable pieces by drawing a basic diagram of the main components (alternator, battery, fuse bock, lights, stereo, etc. ) and figure out where to physically locate each one in the truck. Using distances and load requirements of each, you can figure wire sizes, and any fusing required for each branch of the tree you are building.
Good luck, and keep all the smoke in the wires.
I posted one in "grounding aux battery". It's pretty basic. I'm doing pretty much what you described for the alternator, battery, fuse blocks (2) to start. Most of it is planned and even built. Stumbling block is building the charge warning circuit. Where to branch off, attach it to switched power, and where to physically locate the fuses. I might use these things called add-a-circuit for the small amp circuits like the charge warning and the ignition wire circuit. They look better than the cutting clamp style splices.
 
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