Tatty2

We purchased a 2011 front wheel drive Ford Edge to pull behind a 42ft Class A motorhome. We had a Blue Ox towing kit installed and we followed the guide lines by the owners manual to put the car in neutral and auxliary mode. All went well for 2 days, we stopped every 500 miles and ran the car for 5 min. Then on the third day we had gone 250 miles and the battery was dead. Do we need to check in to battery disconnect? Any advice would be appreciated.