If you're going to long-term store a car like an XJ8, you need to put a battery tender on the battery. Otherwise you'll find it dead after 2-3 weeks. You can buy an inexpensive one at Wal-Mart, about $20. You didn't say how old the battery is, but it sounds like it's at least 3 years old, and probably older.
Take the battery to your local auto parts store and have them load test it. You'll undoubtedly find that it's 1) not charged, 2) not taking a charge, and 3) needs to be replaced.
Thursday, July 21st, 2011 AT 5:12 PM