Dual Battery Questions

[strocket]

Hey guys,

Well I guess first I should tell yall how I want my dual setup to work, and then see how I should do it. I want to have two optimas. The first optima I want to be a red top and I want to hook all of the stock stuff up to that. As in im just going to to swap an optima for the stock battery I have now. Then I want to have a yellow top. I will run all of my aux stuff such as lights, and sound sys. off that battery. Now here is where my questions come into play... I have been reading into both battery isolaters and also the dual battery setup kit that Painless offers. I would like the alternator to charge both when ever the truck is running. Then I want to be able to use that back up battery to crank my truck if my starter battery is dead. I wanted to buy the painless kit, but I was a little confused on how it worked. Should I buy both the painless kit and a battery isolater and hook them both up? Im also trying to stay away from having the aux battery work in conjunction with the starter battery. I want the starter battery to stay at 12V. How would I hook up a dual battery sys so that I have two seperate batteries that are both being charged when the truck is running, and use the aux battery as a "jumper" but only when needed? lol sorry if this sounds confusing

 

[BrooklynBay]

I have this exact setup on my 88. I have an isolator, and a starter solenoid connected across both positive terminals (primary, and secondary batteries). While driving, the alternator is charging both batteries, but when I crank to start it, my second starter solenoid kicks in, makes contact with both positive battery outputs, and then provides twice as much current to start. The second starter solenoid enables both batteries to temporarily be in parallel while cranking, then disconnects them.

 

[strocket]

is there a way to have that solenoid active by switch. i only want them to be in parallel when I choose.

 

[BrooklynBay]

You could add a switch to power the secondary solenoid's coil. It would provide positive 12 volts. I also have a manual key switch on mine that uses a special plastic key. It is a high current battery cut off style switch. Harbor Freight sells them as well as auto parts stores, and West Marine.

 

[BKennedy]

I am just getting around to installing a second battery in my Explorer. I want it for winching and the off road lights, mainly, and secondly as a back up battery. I have a red top Optima for the first battery, and a yellow top for the second battery, for the deeper cycle benifits. I am using a isloator, but want to be able to use the yellow top as a jump start battery, in case the main is run down.
Can I run a jumper wire between the two wire mounting points on the isolator (one for each battery) with a heavy duty battery cut off switch? Or would that not do any good, because the isolator only isolates the charging and drain of the batteries?
If that won't work, could I run a heavy gauge wire between the two positive terminals of both batteries, with a battery cut off switch?
Now, my last question is...do you tie in the isolator directly from the alternator, or the starter solenoid (the second largest red wire going to the battery)?

 

[BrooklynBay]

The main wire of the isolator is connected to the alternator. The other terminals are connected to the primary starting battery, and the secondary auxiliary battery. You could connect a starter solenoid between the 2 positive battery posts to jump both batteries together during cranking. This extra starter solenoid's coil would need a connection to your existing starter solenoid to get the power from your ignition switch during cranking.

 

[BKennedy]

Thanks

 

[Blee1099]

I'd suggest just getting the 12voltguy's dual battery kit.. it only cost $109 shipped.
http://www.12voltguy.com/catalog.0.html9.0.html

 

[BKennedy]

I thought about that, but I have enough switches in and under the dash already (three sets of off road lights, ARB, CB, TQ lockout, dome light off, etc...). I already purchased an isolator because I do not want to have to think about it at all, or see it inside the cab. This way, I can wire a link to the two positive posts on the batteries, with a heavy duty battery switch in between, all under the hood. Then, if I need the second battery to jump the first, I just flip the switch and flip it back when its started.

 

[BKennedy]

The main wire of the isolator is connected to the alternator. The other terminals are connected to the primary starting battery, and the secondary auxiliary battery. You could connect a starter solenoid between the 2 positive battery posts to jump both batteries together during cranking. This extra starter solenoid's coil would need a connection to your existing starter solenoid to get the power from your ignition switch during cranking.

Hijacking the thread again....
I have it all installed and have one question; The only wire I moved was the main charging wire from the alternator to the "1" terminal of the isolator, then ran a new wire to the alternator from the "A" terminal of the isolator. Is that all I needed to do? I was reading the instructions (I know, bad idea) and it said I might need to move a voltage regulator wire as well. I check all the wiring with a voltmeter and got the right readings, and both batteries are charging fine. I am getting a "Check Engine" light, but it might be because I degreased the engine and got some water in somewhere its not supposed to be (has happened before and light goes out after a few days).
Here is a few pictures of how I situated the stuff in the engine compartment to get it to fit. It was a great excuse to buy a new welder.

I put the isolator to the right side of the radiator under the grille so I did not have to lengthen the stock alternater wire. I put it all back together before I took pictures. All those wires used to be on top of the stock wiring on main battery. Oh, I did not get the yellow top Optima because of a cost issue. It costs more than the blue top now and is half again more than the red top. As little as I use this rig (1 - 2 times per month), I figure it will be fine with the red top for years.

 

[BrooklynBay]

The engine compartment does look very clean! I would suggest reading the code to see what the check engine light is showing.