2005 xj8 super v8
Having a problem that I did not find on this XJ 350 forum, but I could be wrong. Been leaving car with 12.7 volts at night and coming back next morning with 12.2-12.3 left!,
On the ammeter around negative cable and or positive registers .8 sometimes .06mA so varies as if intermittent! Even that I leave it for an hour for everything to power down.. The way this started is that I've been having problems with the alarm going off so changed battery and thought it was the culprit. Now same thing happening with the new battery. Testing battery and alternator seems both are good. Voltage would be 12.65 and drops to 12.2 in a day for some reason. I think I have a drain somewhere. Any ideas, reports or list of culprits on these cars that is drawing the amps at rest? I disconnected bulbs in trunk etc.. to no avail yet. What are the most common fuses to check maybe>? As everytime you check a fuse you need to wait an hour for all to power down again. 2005 XJ8's super V8 had it for three years and been a great car.
Thank you..

 

It's possible you could have a drain or more likely just a crap battery. Drains are a pain to find in modern cars. Most times you need to have an amp clamp and device to record overnight to see what is waking up. You should have all the doors closed and everything locked, allow the car to go to sleep and watch the amp clamp while this is happening. I find most of my drains come from aftermarket items installed, audio system, or glove box doors. Most manufactures consider anything below 40 mA acceptable

 

Hmmm... If you read over in the S Type section... Faulty ignition switches have been found to cause parasitic draw by not letting the modules enter sleep mode... I'm pretty sure Jaguar shares a bunch of electrical components across models... Maybe look at that?

 

50 ma is about right for normal power draw. To test, remove the plus battery cable and install an ammeter between the pos battery post and the positive battery cable. Just watch the meter, there is no power down mode that I know of, when you turn the ignition off, it all goes to where it's going to stay. If there is more than 50ma drain, just start pulling fuses until the meter drops, you then have the drain. In order to test the battery properly, you need to load test it with a resistance tester. Just loooking at voltage is not enough. The tester needs to be capable of testing a 1000 amp battery.

 

Thank you for the advise guys. On the battery issue I did take it to NAPA where I bought it and they tested the battery and alternator and seemed strong and running well. Then I took to Autozone they said same. Battery is good. But I really had a suspicion that it was the new battery that is the problem, maybe time to go buy another battery and put it in and see if same problem persists. As for the ignition I saw something on that yes, should I spray WD40 in like someone suggested? is there a better way to test that as well? I'm sure there's a way better than just to spray oil :-)

 

Your car may fall in the VIN range of the attached TSB.

 

Ok case solved. Wanted all of you to know and hopefully to help someone else who looks for that thread. It was not the battery, I disconnected the Hood(Bonnett) unplugged the sensor and bypassed it with a wire from one end to the other. Alarm never went off again! Case closed. I guess the new battery was reading low every time I open the trunk cause of the immediate draw of amps when you wake everything up. Amp used = Voltage
down. Thanks for everyones help on this.