I've had my XJL for 18 months and love it, but recently (last 2months) my low battery run engine light comes on when entering the car after being parked for 12 hours. Dealer has replaced the battery twice and replaced battery cables with a sensor? would this problem be related to the computer in the car? Any ideas on what this could be? When this first started the battery went completely dead and I had to jump the car.
Thanks

 

When you park the car, it's not left unlocked with the key in the ignition is it?

This leaves several systems powered on and can cause rapid battery drain. The 'correct' method is to lock and arm the security system. Everything is then powered down to 'sleep' mode.

This may seem OTT if you're in locked, secure parking but is still the best method.

Graham

 

I began getting a low battery warning shortly after bringing home my 2012 XJL in April. Although I never left the key in the car, I routinely left the car unlocked in my garage overnight. I would then see the low battery warning the next morning. Once I began locking the car as Graham suggests, the warning disappeared and has not reappeared since.

 

Thank you Graham,
The service mgr suggested the same thing today and I will set the alarm from now on to see if this helps. Thanks again for the suggestion.

 

Last year on this forum there were similar complaints about the battery, then it all fired down.
One recommendation that was consistently made was to make sure that your key fob is out of detection range of your car at night. I do this, and have had no problems.

 

You must Lock your car each time you leave it. as said, the car's computer will continuously search for the key if the car is not locked, ie., search mode. Locking the car places it in sleep mode and does not drain the battery. When car is locked, car can be left for weeks without draining battery.

 

A zero cost solution - my favourite kind of fix.

Checked the Owner's Handbook and nowhere in the 12 pages on locking and arming does it mention this basic requirement.

Graham

 

Yep, seems to me this is a design concept that is just not intuitive. A simple timer would have solved this problem. If the car is left unlocked, the timer would shut off this "searching for a key" function. I don't know of any other key-less entry systems that present those battery drainage issues. The spirit of Lucas is still poking around Jaguar's electric engineer's offices...

 

My initial thinking after one day of ownership of a new '12 XJL is that Jaguar has completely gone nuts with power management on this car. As I looked at various cars on the dealer's lot I noticed that most of them displayed "low battery warnings".

When I purchased my car the salesmen insisted that I start the car and run the engine while he was going through the workings of the control panel. Later, I read in the owner's manual that you must run the engine if you have the ignition ON and the interactive panel powered up.

So, I tried to outsmart the system, figuring that I did not want to run the engine for 4 hours, which it may take to program everything, including the loading of 10 CDs into the hard drive memory. I put my 12 Amp charger on the battery and begun uploading the first CD. Well, after about 15 minutes I got the low battery warning and 3 minutes later my display panel went black and the upload was interrupted. It was obvious that the 12 Amp charger was not enough to compensate for the drains.

So, I charged the battery and took some current measurements using my clamp-on ammeter.

Opening the door and having all those internal lights come on resulted in about 15 Amps flow. After the lights turned off automatically, turning on the ignition and turning on the CD player resulted in an eye-popping 28 Amps of current flow. The low battery warning seemed to come up when the battery voltage sagged to 12.5 Volts.

With nothing running, no internal/external lights-on, the system was still drawing 7.0 Amps. When I locked the car, as recommended by a number of posters here, then opened just the trunk so I could get to the battery, the current dropped to less than 2 Amps. I assume that it would drop to near zero when the trunk is closed but, no way for me to check that.

So, after one day it is clear to me that the XJ is using incredible amounts of power just to run its internal lights, LCD panels and audio player. (BTW, during my measurement the player was set to minimum sound volume. I do have the stock 600 Watt audio system). It seems that taking your wife/girlfriend to a nice romantic spot and turning on the radio or CD player while the engine is shut down is not going to be an option. Having a set of jumper cables in the car, on the other hand, might be a good option.

 

If you are going to store a set of jumper cables, don't keep them in the trunk. There is no mechanical lock for the trunk, only electronic. To jump the car with no power, there is a power connection next to the fuze box under the hood to provide just enough power to open the trunk , but you *can't* jumpstart the car from the hood connections -- You will fry something if you try...

 

Also observe the warnings in the Driver's Handbook about NOT connecting the booster cable directly to the negative terminal.

Ignoring this warning is another good way to fry sensitive electronic components.

Graham

 

Most of the time the recommended procedure in jumpering is to make the negative connection somewhere on the chassis, AWAY from the dead battery. The primary reason for that is to get your hands and face away from being near the top of the dead battery when the final parallel connection is made with an other battery; in case there is a dead short circuit in the dead battery the large inflows of current from the donor battery could cause lots of heat, therefore rapidly expanding gases, in effect blowing up the battery. If one has his/her face over it, the exploding sulfuric acids could cause serious eye and skin injuries.

Albert

 

Do you think this is a problem that will be solved in the next year model? because after all, how embarrassing is it to carry a jumper cable with your $80K+ car?.... Business trip, leave the car in the long-term parking spot at the airport only to come back a week later to a dead car?.... Not good. Hello Jaguar in England... are you reading this?

 

Remember that you are only dealing with a 12V system, so even 28 amps of current draw relates to only 336 watts of power--that is not a large load by any means for accessories.

I don't think the XJ is a power hog and many cars will run down their battery when they sit without being started for an extended period because, in general, everything does not shut off when you turn off the ignition. IMHO it's always good practice to not turn on your ignition without starting the car.

P.S. My XJ is my daily driver and I have never gotten a low battery warning nor have I ever needed to use a battery charger.

 

28 Amps is a lot of current, particularly when only backed up by a 90 Amp/hour battery, as in the XJ. These new electronic controls are cool but, I miss the old days when you could sit in the car and just turn on your radio or player and listen to music for hours, if you wished, on the battery. Now, you are required to turn on the ignition, light up the virtual instrument panel, plus the touch panel, and draw 28 amps that will basically go for maybe 15 minutes before the Low Battery alarm activates and the screens shut off automatically.

I find the idea of having to continuously run a 5.0 liter, 385 HP engine just to power your music simply ridiculous. Now, I trust that I will adjust to this strange characteristic and have no problem with the battery during my upcoming years of ownership of the XJL. In the meantime I will use my next multi-hour trip to load my 10 favorite CDs into the hard drive while driving. Hope it won't get me into an accident, handling the discs and the many steps on the touchscreen that the loading of the disc requires.

BTW - Today I did measure the battery drain with the car locked and it indicated 0.1 Amp, which is normal for most cars. So, just by sitting the XJ should not run its battery down.

Albert

 

I don't mean to make a drawn-out bitch session on this subject, BUT...

I turned off all interior lights as per HouTexJag's advice (thanks) and went on to fully charge the battery with my external charger.

Then, I packed the car for my upcoming travels that involved opening the door and the trunk maybe 3 times each. When ever I opened the door the two LCD screen, the virtual instrument panel and the touch panel would light up and display the Jaguar emblems and stay on for a few minutes. Then, I proceeded to wax the whole brand new car.

After getting done waxing I opened the door one more time and the "Low Battery Warning" display appeared. I quickly measured the battery current draw and it was 18.7 Amps, all for the two LCD displays. That is 12.69 V x 18.7 = 237.3 watts of power just to display the Jaguar logo. In comparison my 52" Sony LCD TV, screen and complete internal circuits, sound amplifiers, etc. draw 289 Watts of power. That is what I mean that Jaguar has gone nuts with the power management on this car. From what I had seen on the dealer's lot, all those cars with Low Battery Warnings, this must be the rule for the 2012s, rather than an exception.

So, what is wrong here? My take is that, for one, the settings for the "Low Battery Warning" alarm are set too low in the software. As the car was displaying the latest low battery alarm I quickly measured the terminal voltage right on the battery in the trunk; it read 12.69 VDC on my high quality digital meter. That is normal voltage level and it should not be alarming at that level.

Albert

Edit: I talked to the dealer shop foreman regarding the above situation. He told me that when I charged the battery, connecting to the actual battery terminals, the charging current was not seen by the battery monitor module which is installed right on the negative terminal. After looking at the setup, I agree with his points. So, I charged the car again with the charger set outside of the battery monitor (connecting the negative charge cable to the chassis, instead of the battery post) and the battery now held up far better under the above conditions. So, it is true that the battery monitor is looking at the discharge current rates, as well as at the incoming charge rates to determine the condition of the battery and activate (or not) the low battery alarm. At this point I am quite content with the situation and simply will adjust to the system requirements.