Wiring Help Diesel 2 starter batteries + 1 audio battery LOOP Issue

[Reboot]

Hey all and thank you for taking the time to help.

I had installed a 3rd battery in my truck and it was draining my batteries. Then i took it to an audio installation place and they suggested and installed an isolator to solve this issue. All said and done i was thinking my issue was gone. I have been eating through starter batteries for a year now and i couldnt find the issue so i retraced the wiring for my car audio and figured out that the installers didnt fix the issue but created another issue entirely.

What is happening is when my truck is off, the front batteries are back draining down the wire to the alternator which attaches to the input wire to the isolator and then back to the starter batteries and audio battery.

The Exciter wire that has to be hooked up is creating a loop and i dont know how to stop the loop from causing the back charge. If i unhook the exciter wire then my alternator does not put out a charge.

Attaching a horrible windows paint illustration lol.

Thank you.

View attachment 26557094

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[winkychevelle 10+ year member]

The only battery that needs to be connected to the isolator is the audio battery

The exciter wire to switch the isolator to feed the audio battery should get it's power from a key on off source not the alternator itself.

Typically batteries don't just drain even when adding more to a circuit. Check all the grounds and all the connections making sure they are tight and bare metal to metal contact points.

 

[Reboot]

So, i should just remove the isolator and install a solenoid relay to key on off the charging to the back battery when truck is running only? the isolator i am using is a diode isolator, i think its the wrong kind for a 2+1 battery setup.

All of my grounds are good and grounded, audio battery is also grounded to the frame