I am having a problem with my '99 XJ8L. I leave to go to the store about 10 miles away after not driving for nearly 5 days (out of work), and it starts up just fine in my driveway. Tempreture outside is in the 60's with no freeze. In Southern Louisiana. When I come out of the store, sometimes, not always, it will not start. The car is dead, dead, dead. NO lights, no dashboard, door rings, nothing. A quick jump-start and it fires right up, and then it's fine. I took the 3-year-old battery to AutoZone and the battery was good. No dead cells however, it was only at a 40% charge. I charged it and it starts up but, who knows for how long. I have seriously only driven the vehicle less than 2000 miles in the last 8 months. Could there be something that is draining my battery while I am in the store? My lights are on auto on/off, always. Does this behavior indicate that something else is draining my battery or not charging my battery when I drive? Ignition seems fine, starter seems fine. It's a mystery and I would like to get some ideas about a possible problem. Is there a setting I have missed?

 

Use a voltmeter to check the voltage across the battery terminals. There should be a minimum of 12.6 volts present, if not, charge the battery for five hours at 2 to 5 amps and retest it. If there is still less than 12.6 volts present, the battery is failing or weak and must be replaced.

If the vehicle is not being driven for extended periods, use a battery maintainer to keep the battery fully charged and to avoid it becoming sulfated.

 

Thank you. I will do exactly as you say to see if it happens again.

 

Try cleaning battery connections

 

Also try posting in the forum for your car which is an X308 made up unitl the cars in this forum came on sale in 2003. The two models of car are totally different even if they are styled the same.