Car was excellent in every way until I left it at the airport for a week while I was away. Battery was flat(2.84v). My local dealer took it in and gave it the latest software update. While it has not gone flat yet, if it is left for a day or two the battery voltage drops to 12.22v to 12.11v each time having been on 12.60v to 12.70 v. Never had this before on any of my previous 6 Hondas. The dealer said that the latest update should cure the problem. I'm not so sure.Anyone help here.