You have to have the charge cable connected. We took a voltage reading before connecting it to the system. At that time it read 29 volts on the output cable. That being the case, we were a bit hesitant to hook up the cable. Today I disconnected all the sensitive electronic equipment and hooked it up and took a new reading. Now its at 14.7 volts.
I'm just not to familiar with the dodge charging system so learning as we go. I'd rather be cautious and not fry a bunch of gauges.
I got some learning to do as well!
If you find you need more cooling when you do get it done, think about water/meth injection.
got a bottom side view of the hotbox?

Probably time for a call to someone like psc?