What pin on VCM indicates the DC-DC converter is operating?

[biscuitshine]

I've installed an auxiliary 12v battery and battery charger in the backseat of my 2017 Leaf SL. The intention is for the auxiliary charger to only run when the DC-DC converter is on. As far as I can tell, the DC-DC converter is on when the car is in one of these states:

• Vehicle is on
  Vehicle is off but in Accessory mode
  Vehicle is off but charging

I was hoping I could tap into the 12V accessory outlet to use as the signal for when to run the auxiliary charger. Unfortunately I just discovered that the accessory outlet does not energize when the vehicle is charging. Any idea where the easiest way to tap into a 12V circuit that is on when the vehicle is charging? Is there a pin on the VCM that would serve as an indicator that the DC-DC converter is running? Thank you!

Work in progress
https://imgur.com/Vc7Ahj0

 

[nlspace]

What are you using to supply power to the Renogy DCDC charger unit--are you connecting to the HV of the Main Pack?

Will the second auxillary battery be totally isolated from the primary aux battery and vehicle chassis?

 

[biscuitshine]

What are you using to supply power to the Renogy DCDC charger unit--are you connecting to the HV of the Main Pack?

Will the second auxillary battery be totally isolated from the primary aux battery and vehicle chassis?

Sorry for the incredibly delayed response. I need to figure out how to get notified for posts.
I am not connecting to the HV. I ran 4awg wire from the car's 12V battery. The auxillary battery is isolated from the primary 12V battery by the charge controller shown in the photo.