How to make a cheap isolated dual-battery setup for $50

[dwh]

Yea, that's sort of a difficult question, because every rig is different, so you have to sort of "wing it".

My truck has an "Add a Fuse" doohickey stuffed into a fuse slot that is ignition hot and feeds the solenoid:

http://www.wiringproducts.com/conten...e_holders.html

atm_add_a_fuse.jpg


As for the power draw of the solenoid - not much. Mine draws about an amp.

[SLO_F-250]

Yea, that's sort of a difficult question, because every rig is different, so you have to sort of "wing it".

My truck has an "Add a Fuse" doohickey stuffed into a fuse slot that is ignition hot and feeds the solenoid:

http://www.wiringproducts.com/conten...e_holders.html

atm_add_a_fuse.jpg

As for the power draw of the solenoid - not much. Mine draws about an amp.

Thanks for the intput. My truck has dual ignition fuses in the fuse panel under the hood. Both are 50amp. Right now I am using a wire under the truck that is hot when the ignition is turned. Just am a bit worried because the wire I am pulling from is pretty small. Maybe 8ga. Im running 12ga to the isolator.

Am I rolling the dice, or not too big of a deal? Or should I do something different? Leaving for my trip in 2 days and I doubt I can find that part anywhere, plus I need it 50amps.

[dwh]

Um...#8 is bigger than #12.

But it should be no big deal, the solenoid doesn't draw much. What size fuse protects the wire you tapped off of?

[SLO_F-250]

Um...#8 is bigger than #12.

But it should be no big deal, the solenoid doesn't draw much. What size fuse protects the wire you tapped off of?

Yea, that is why I was wondering how much draw it has. Besides getting the "add a fuse" above, I took the directions as stuffing that wire into one side of the fuse connection and then putting the fuse back in. Is that seriously what some people are doing? I guess its not that off the wall.

Connect a 12GA wire from pin on the isolator to a fuse in your fuse box that is only 'hot' when the key is in the 'ON' position (aka the truck is running)

From first post in this thread. That is what I am talking about.....

[Truefire]

Interesting and highly informative thread, thanks for taking the time to compose such a good posting.

Chris

[dwh]

Yea, that is why I was wondering how much draw it has. Besides getting the "add a fuse" above, I took the directions as stuffing that wire into one side of the fuse connection and then putting the fuse back in. Is that seriously what some people are doing? I guess its not that off the wall.




From first post in this thread. That is what I am talking about.....

Well...I don't think evldave actually said to stuff the wire under a fuse...

And no, it's not recommended.

You can find a wire that is hot with the ignition, and tap off of it. If you use the same size wire or larger, then the existing fuse will protect both wires, and almost certainly be large enough to handle the extra one amp or so of extra load added by the solenoid.

[G35Vortec454]

This is a great thread.

One thing I'd like to comment on is the voltage drop of diode isolators. You can solve that problem by using an adjustable voltage regulator for your alternator and a battery sense wire to the battery, far from the alternator armature post. That way you can set the alternator to put out the proper voltage AT THE batteries.

[Ozarker]

Added to favorites, stickey? Very good info, thanks...

[Mudrunner]

Okay I have a question real quick I know most basic automotive wiring, but reading through this I had some questions. So is Isolating the batteries mostly for charging purpose? Or is it so that you don't have to rewire certain things like the Cig lighter and winch so on and so on. Because to me I would just wire them in with a separate fuse block so if I sold the truck I could just make it removable and save it for another ride.

[4RunAmok]

Isolating (separating) the batteries is to protect your starting battery. You don't want to be drawing off both batteries while your vehicle is not running.

Combining the batteries while the vehicle is running is for charging both batteries. And for this, you want to use a high-amp constant duty solenoid, as opposed to a voltage reducing diode-type isolator. These diode isolators will end up reducing the charging voltage so that both batteries never receive a full charge.

To make the system simple. Run two AGM batteries, put one inside the cabin, run all your accessories on a fuse block from it, and remove it when needed. Don't forget the breakers, especially the one in the front to kill the line after you removed the rear battery.