I have no voltage across auxillary charging terminals in trunk of my 2010 jaguar xkr. The battery says 13.7 volts but car won't turn over. Battery is a 1 yr old AGM but I suspect something is drawing current as it has gone dead twice in the last week. Any thoughts would be appreciated thank you

 

First thing, why is your battery showing 13.7v when a fully charged battery is 12.6v. I would change the battery for a good, fully charged one and go from there.

 

Volts don't necessarily mean Amps.

 

yes on a one year old battery that went dead twice this week, something is drawing voltage. Referred to as a parasitic draw.

Your battery should be under warranty, return it to the store, have them test it and replace it.
Put a maintainer on it and begin your search for the draw. This is a great video on how to test for a draw.

This is a simple process to follow, even if you're not DIY. You can at least isolate where the draw is coming from. Pay attention to his comments after he isolates the draw, such as the system taking 30 minutes to go to sleep as ours do. Also, doors closed etc.

 

13.7 volts - could be a poorly calibrated cheap meter.

Does the ignition system turn on - does the centre display come up - not enough info here.

 

Thanks to all, battery is now holding a charge and vehicle will start, still no voltage at the aux terminals though, will get dealer to investigate when car goes in for oil change. I can't install the luggage separator and consequently can't get rear windows up, will be a breezy trip to Scottsdale

 

OK I guess I am missing something. By the Aux. terminal do you mean the positive post behind the left plastic grill in the trunk?

 

Yes, that's the one. I have 12.44 volts at the battery but nothing in the trunk terminals, thanks for your interest

 

Have you looked under the rear bumper and under the terminal to see if the main wire from the battery is somehow disconnected.

The cable runs from the battery and comes up into the trunk through an insulated post. So look under that post location in the trunk.

 

I had two similar occurances with my '10 XKR years ago. After driving the car, shutting it off normally, came back in 2-3 days and the car would not even click over. A check on the battery voltage indicated a shocking low of less than 3 volts. Obviously, something was sucking the battery down into the dirt.

I recharged the battery and placed an ammeter in series with it to check for battery drain. I did this consistently for a while because the dead battery issue only popped up rarely. While observing the ammeter current draws, I realized that the XKR electric system does NOT shut down all at once. It shuts off in stages over roughly 10 minutes after exiting and locking the car. Finally, I captured an instance where the current draw would not shut down completely but, continued indefinitely at a range of 1.4 amps. That exactly matched the scenario where it would take 2+ days to completely suck the charges out of the battery.

I took the car to the dealer and they referred to a TSB (I think, this was years ago) which stated that "rarely, the infotainment system fails to shut off upon exiting the vehicle". They simply ran a software update and my car appears fine ever since.

A voltage read of 13.7 on your battery is normal only while it is being charged or shortly after the charging is removed.

 

I have attached the relevant TSB.

 

Thank you very much for this informative post. I just caught it now and will pursue this as the car is at the dealer now

 

You may want to consider buying a CTEK MUS 4.3 battery maintainer to properly maintain the battery in the vehicle. Many of us Jaguar XK/XKR owners are using this device. I own 4 and use them on my premium automobiles. I have never had any respective battery issues since using the CTEK battery maintainer.

https://www.amazon.com/CTEK-56-864-A...s=ctek+mus+4.3

https://www.jaguarforums.com/forum/x...lation-107738/

The information about may help your cause to eliminate battery issues.
..

 

I had the dealer do the mentioned TSB, only $160, not bad for .4 hours according to the procedure. Scottsdale Jaguar will never see that car again, also$250 for the oil change and $160 to recalibrate the convertible top. Anyway picking it up today will see if they managed to fix the 0 voltage in the trunk. I did check the wiring under the bumper and everything looked to be in order but I will have to have that situation rectified prior to putting the car in summer hibernation as I will never take that luggage separator out again if I'm not next door to a dealership. Thanks to all for the contributions.

 

Have the car back, they forgot to check out the zero voltage problem or do the OBD non compliance .recall.
I will have to get to the bottom of this problem but at least I have a few months left to do so.
Again thanks to all.

 

If you still have 0 volts on that terminal then I think you may have a bigger problem then you think. Measure it again and use the stud in the spare tire area as your ground as it states in the OM . Then touch your pos. meter probe on the terminal under the rubber boot. Tell us what you get because if you hook up a smart charger you would most likely use this terminal as the pos clamp.

 

Do you mean the boot under the car because there is no boot over the positive terminal in the trunk just the bare aluminum bracket that seems very flimsily attached.. I must admit that I didn't use the post as my neg, just the other aluminum bracket beside the pos. This is also where I hooked my battery pack to try to start it when the battery was flat. Didn't work though Mea culpa Stupid!
I notice everything else seems to be functioning correctly after my visit to the dealer

 

It might be a good idea to take some pictures and post them here so we can see what you are talking about because at the moment, from your descriptions, it sounds like you are getting confused.

 

Unfortunately there is no cure for stupidity, I have been using the wrong location as positive. I just noticed hiding down there, a boot covered terminal and, of course, it is giving me a reading of 12.44 volts. I apologize for wasting people's time and again thank you for the responses. It would seem that after getting the aforementioned TSB update that the battery might no longer have a parasitic draw, here's hoping!
When my face returns to it's normal colour I might dare to mention my key fob which seems to have lost it's programming over the summer, I have tried 2 new batteries to no avail.

 

I agree with Jim, what you are saying isn't tracking with what is in the trunk. In the inside of the trunk there the Positive Battery terminal for charging, on the drivers side. When you pull the plastic cover that exposes the rear brake light, down and inside a bit towards the rear tire well there is a rubber boot covering the Positive Terminal, there is a very thick battery cable that terminates on that connector. It is quite large, nothing could be called flimsy about that cable or connector!