Auxiliary (Dual) Battery Setup Question

[project.blackstar]

Im going to be installing a second battery in my truck to run all my accessories off of. Ive got way too many things running off my one main battery that I fear one day my truck isnt going to start and ill be out in the sticks with no other cars around to get a jump from LOL. I plan to run a large fused distribution block (can handle up to 280AMP's) from the second battery with a 4 Gauge Wire directly from the battery terminal. From that block, two smaller 100AMP fuse blocks with 8 Gauge allowing me to fuse 6 accessories each.

Ive read that i can simply hookup a second battery in the auxiliary battery tray (drivers side) by running a 2 or 4 gauge wire from the accessory fuse block. A little skeptical about how easy that really is, but if its really that easy then that works perfect! Ive read that doing it this way will also charge the second battery, any one know for sure?

What size maxi-fuse would I need to run out of the factory accessory fuse block stud when hooking up the second battery? 60AMP? 80AMP? 100AMP?

 

[Dr.Zoom]

I'm working on a dual battery setup myself, but haven't actually installed anything other than the battery tray and I put my new battery on the tray, but it's not connected to anything. If you hook them up like you've described, they will both run down at the same rate and you still may wind up not being able to start your truck.

I'm planning to run a smart isolator that senses when the starting battery gets below 12.7 volts, then switches to your auxiliary battery, so your starting battery always has enough to start your truck. Then when your engine is running and you're charging again and your starting battery is above 13.2 volts it switches over to let your aux battery charge. The isolator is set up so that you can run a switch to your dash that connects both batteries for one minute if your starting battery is failing and you need a jump.

The unit is a Cole Hersee 48530.

I found the write up on it here: http://www.hardworkingtrucks.com/gm-1500-dual-battery-install/

To me, this seemed like the way that made the most sense.

 

[project.blackstar]

Thanks for the reply! While I dont plan on running any of my accessories without my truck running, it would be nice to have the peace of mind that with the isolator that the main battery would ALWAYS have enough juice to start the truck!

Does that isolator unit come with the switch you had described or do you have to purchase it separately? If im understanding this correctly, this would eliminate hooking the aux battery up to the factory accessory fuse box correct? And a simple in line, 200AMP fuse for the isolator? Sounds like it is fairly easy to wire if thats the case, connect to the main battery w/in-line fuse, connect to the aux battery and ground. Found one on Amazon for $120, not bad.

 

[Dr.Zoom]

It doesn't, you have to get a momentary switch. A Rear Hatch switch is what I'm going to use so it blends in with the dash. I'm going to try to change the lettering on the switch also. I've cleaned off the old white base coat used for the lettering and charcoal colored paint, but still have to repaint the white, make a reverse stencil and then hopefully match the original charcoal color.

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[project.blackstar]

ahh okay, no big deal. I am getting several rocker switches with custom labels, so I will just get one for the aux battery jump as well!

I know you had said you dont have the isolator yet, but do you know how the cables from the main battery, aux battery, and ground are connected to the isolator? Are there studs on the isolator or a cable lead for each? Same goes for the optional dash switch, a stud on the isolator to hook up to or?

 

[Dr.Zoom]

It's been a while since I had the plan fully visualized in my head. The purple wire is the one that you'd use to connect the momentary switch and it's just a loose wire as far as I can tell. If you didn't use, you'd tape it up so it didn't ground. Here's the diagram. You fuse between the batteries and the isolator. Which takes us back to your original question of what size fuse. Which I don't see in my notes and I'd have to figure out.

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[project.blackstar]

Ahh okay thanks for the pic! damn so it looks like you would need two fuses then... The isolator is 200AMP, so it sounds like I would need two 200AMP in line fuses. Blue Sea makes an inline fuse block thats capable of handling up to 300AMP: https://www.bluesea.com/products/7721/MEGA___AMG_Safety_Fuse_Block

 

[Dr.Zoom]

As I recall, you'll never be pulling 200A and the fuse you'd use was less than that. My alternator only puts out 105A.

 

[Dr.Zoom]

I didn't phrase that well, but you get the point.

 

[Cokeman95]

If you're able to match the paint, please post the link to what you used. I'm planning on doing something similar by using a cargo switch for the override switch on my electric fans.