I have a 2001 XK8 Conv. I heard that just parking her in the garage WITHOUT locking it with FOB can cause a drain on the system because the computer will NOT go into the "sleep" mode. Can anyone substantiate that? Also I live in one of the hottest places in Texas last we had 100 straight days of 100* ambient temp. I purchased the Bluetooth OBAD II plug in so I can monitor the temperature and the highest the car got was 212* at over 105* ambient. Is that good, average or bad? BTW I have used several tips on this forum such as the antenna on/off switch in consul, opening the air box and removing center muffler. Kitty runs good!
Thanks everyone!!!

 

I have tried to find a difference in battery drop vs mode in the XK8 and can not see a big difference. I normally keep it in the garage unlocked with the top down and the battery is still 12.5- 12.6 after four or five days. Top up and locked no difference. But that's not long term. If I don't plan on using it for a week or more I use a battery maintaining charger. My XJ6 can go for two weeks without a drop.
As to the temp, I think that's very good results.

 

It will go to sleep locked or not.

It will not go to sleep with the key in the ignition though, even with the key in the off position.

212 max. temp. is about right.

 

It was 102F in Dallas today. I got stuck in traffic due to a wreck. Sat through one intersection red light for 3 changes. Car got up to ~213 (using RealGauge) with the AC running on auto.

Sounds like you're about right.

Also, I never lock my car in the garage an battery does not drop overnight. Longest time was over a weekend and she started right up.

 

+1 to taking the key out to put the vehicle into 'sleep' mode

ALSO - don't leave the Bluetooth adaptor plugged into the diagnostic port. The port has a permanent live feed and this will drain your battery.

Graham

 

And if you leave a door open, you will be drained within a week. Even if the door and interior lights switch off after a while, the computers are still live.