Camper Battery charge ignition sense wire

I have a battery manager for my camper and have had it set to auto which stops charging when the starting battery falls under 12.3 volts or something. It also has an ignition mode that will start when a circuit is hot associated with the ignition.

Help me pick a circuit to piggy back off in the fuse box on the left or right that will be off when the engine auto start/stop at a stoplight and on when the engine is running, but needs to be a low amperage circuit. I looked for the alternator fuse to tap into but it's like 20amps.

 

I used the driver side under hood fuse box. As you can see in the second pic I tapped into the unused circuit circled, it is ignition driven.




When tapping into an unused circuit there is no need to use a bottom fuse in the tap. The tap will work just fine without adding the bottom fuse. The bottom fuse is only used if tapping into an existing circuit that is already powering something.

 

He'll yeah, I'll give this a shot. Thanks!