I just bought a 2017 Durango And I'm about to return east for 6 months. I leave my car in my garage in Arizona on a battery tender. Someone told me that my Durango will go into "sleep mode " and that to "wake" it up I have to remove and the re- attach the battery cables. This person also was a tech at the dealership.

 

From the owners manual:

VEHICLE STORAGE

If you are leaving your vehicle dormant for more than 21 days you may want to take steps to protect your battery.

You may:

Disconnect the negative cable from the battery.

Anytime you store your vehicle, or keep it out of service, (i.e. vacation) for two weeks or more, run the air conditioning system at idle for about five minutes in the fresh air and high blower setting. This will ensure adequate system lubrication to minimize the possibility of compressor damage when the system is started again.

The manual makes no mention of a "sleep mode". Your person who is a tech at the dealership is incorrect in that respect.

 

POP the IOD fuse before you go and nothing will put any load on the battery. The keyless system will not work after ~2 weeks I believe (it stops looking for the keys).

IOD is a captured fuse (plastic lock) that just slides up in its position