I have a charge line on mine, ... it's pretty much a no brainer.
7 pin on the coach - 6 pin on the Edge. Use the extra line in the 6 pin for the charge line. Put a fuse at the end connected to the Edge battery, and your done.
This setup wont do much to charge the Edge battery if it's low, but enough to power anything still turned on while towing. It will charge, but at a very slow rate.
You'll never look back ... I've never had so much as a low battery after several hours of towing.
2008 HR Endeavor PDQ - Ford Edge 4 Down
FMCA F374292