I recently purchased a 2021 Discovery 40M and I have to say I am a little overwhelmed. This is our first RV and there is so much to learn. I have just rented an enclosed storage space to protect it from the spring Kansas hail storms. The space is equipped with a 20amp dedicated shore power line. I believe this should be sufficient to keep batteries charged. I read in the manual the 20 shore power must be manually selected. How do I do this? The manual states to manually select on the PCS in another place it talks about selecting the power source using the Firefly display. How do I set up the coach for this power source and is the 20 amp sufficient? Is there anything else I need to do to leave it for a couple months.