If yur standing at the rear of yur car, under the left hand side bumper you will see a thick black lead above the exhaust. It is held on by a nut with a rubber cover over it, mine has bat/starter sticker on it. Took rubber off and all corroded, cleaned it up and waterproof greece on, now no starting issues. It might work.

 

I doubt it's the general cause for battery drain but, it could certainly cause some very unpleasant problems lol

 

I don't think this would cause battery drain but could be responsible for a whole slue of electrical gremlins including not being able to start the car.

 

Grounding on cars is always such fun. Had an old car where I could stand on the bumper and swing on the battery ground lead, but the darned thing didn't pass current. Then there was the self-loosening multiple ground point on the engine of an SUV I had that gave all manner of strange effects. Fixed a friend's car where the distributor baseplate ground fell off leading to a weak spark. That one had baffled all the local pub mechanics for about a week.

Best one I heard was on a buddy's car where the choke cable (remember them?) was getting hot. Turned out his engine to frame ground strap was bad and the choke cable was the best route the electrons could find.

 

I got an other possible cause for battery issues with the XKR.

As you all know Jaguar decided NOT to install gauges in the car to monitor engine parameters. I finally got my Torque Pro app with a Bluetooth and a Samsung phone. One of the parameters I selected to display on it was the Control Module voltage.

To my great surprise during a 60 miles drive last week the displayed voltage was 11.9 while cruising on the freeway. On the way back, the voltage indicated 12.7. Both of those voltage are far too low for charging the battery. The battery needs 13.8 volts minimum to charge but, more like 14.0. When I got home I hooked up a digital voltmeter to actually measure the battery voltage while idling the engine and both the voltmeter and my Samsung agreed at 12.4 volts, again, far too low to put any charges into the battery.

I did not have the time to further investigate, will do so next week but, it appears that something is quite wrong with the charging system, yet, no alarm or notification from the car. If I did not have this new monitoring setup, I'd never know that I have a problem.

 

From my research and reference via the Jaguar Service manual, the manual states the battery MUST deliver at least a minimum 12.55 volts when running.

Your analysis could be right on.

The question that arises, is "What is the resolve?"

 

Check charging circuit. May need to replace alternator.

 

Replying to my own post here with an update. After not placing the XKR on a trickle charger for a couple of weeks I allowed the battery to slightly discharge, down to 12.5 VDC. Upon starting the car the charging voltages are normal, above 14 VDC. When I made my above post I just removed the trickle charger from the battery and the voltage levels started out well above 13 VDC. As it seems, the cars charging system saw that as an unexpectedly high voltage and actually set the voltage regulator to "draw" from the battery when it only charged at 11.9 VDC. Interesting find!

 

A couple of things. Where have you connected the negative lead from the battery charger? The manual recommends that you attach it to a suitable earth point rather than the negative terminal on the battery otherwise the battery monitoring system gets a little confused.

The other thing is that BMS will periodically "self calibrate" the battery:

"To self calibrate, the battery monitoring system first charges the battery to its full condition.

Once the battery is fully charged, the battery monitoring system will discharge the battery to approximately 75% of its full state of charge, but never lower than 12.2 V. The time taken to complete this part of the routine is dependent on the electrical load on the vehicle.

When the second part of the routine has been successfully completed, the battery monitoring system will return the battery to its optimum level of charge. The optimum level of charge will be between 12.6 V and 15 V, depending on battery condition, temperature and loading."

 

I always connect the charger negative on the chassis away from the battery monitor on the neg. terminal.

The discharge process is interesting. I assume you quoted from a shop or owner's manual? I've never heard before a system that would deliberately and automatically partially discharge the battery. When the voltage was running 11.9, something was obviously discharging the battery. In order to draw the voltage down that low it must be a substantial current discharge, particularly knowing that the voltage was at a fully charged 13.5 V prior to that. I'd like to know what is drawing that much discharge current for such extended periods of time (more than 30 minutes in my case).

 

That BMS info is for the XF and XJ but according to the XK Technical Guide that system was 'carried over' to the 5.0L XK when it was introduced so it is not unreasonable to assume it has similar functionality.

 

You are correct. On a 2010 XKR forward with 5.0L engine it is suggested to use a negative body ground or "suitable earth point".

On the 2009 and under 4.2L engine the smartchargers can be connected directly to the battery terminals.

 

I prefer to follow the advice in the Owner's Manual:I realize that others have connected their chargers directly to the battery terminals without any reported adverse effects. I'd rather be safe than sorry.

Jaguar engineered our cars with remote battery terminals for a reason - safety - because hydrogen gas is colorless, odorless, and highly explosive. If you connect your charger directly to the battery terminals you risk causing an explosion. Hydrogen gas can accumulate in the battery compartment even though it is vented. That's the reason for the remote battery terminals - to minimize the risk of explosion. If you use the remote terminals a spark can't ignite any hydrogen gas that may be in the battery compartment.

I don't want to hijack this thread. If you're interested in learning more about the remote battery terminals and battery safety, see these old threads:
https://www.jaguarforums.com/forum/x...lay-ups-73471/ and my posts ##17, 19, 21 and
https://www.jaguarforums.com/forum/x...storage-85201/ and my posts ##15 and 17

Stuart

 

Since my post was quoted above, I will respond.

Stuart & others:

Keep in mind that my comments are related to the installation of the CTEK 3300 Smartcharger that I have referenced on these forums numerous times. CTEK takes into effect the gases that batteries may produce. Keep in mind that the 4.2L engine batteries are vented batteries. It is safe to install the CTEK 3300 Smartchargers directly to the battery terminals on the 4.2L Jaguar engine models 2007-2009. CTEK smartchargers are "SPARK FREE". I have included a link to information on the CTEK 3300 which is widely used by Jaguar owners here on the forum. I have attached specific information from CTEK on the safety of their smartchargers. Some owners may desire to connect battery charger terminals to the remote if they wish. With some chargers it may be necessary, however it is not necessary to connect to the remote when using the CTEK brands of smartchargers. In addition, I would rather connect the CTEK directly to the battery terminals using the eyelet connectors rather than alligator type clips as some owners have suggested.

If your using the CTEK brand, you can connect the eyelets direct to the terminal screws that Jaguar supplies to the car owner on the battery posts. The terminal screws are there for a reason.

If any CTEK owners have concerns about safety, explosions, and wanting to be "safe rather than sorry", please visit the link below and read it throughly. It will provide information directly from CTEK that will end any fears or safety concerns.

CTEK Multi US 3300 | CTEK Battery ChargersCTEK Battery Chargers

Be advised that before I even considered connecting a smartcharger of any kind to my battery, I competed due diligence and spoke directly with the CTEK people over this matter. CTEK was my choice in the end.

I suggest that Jaguar owners of the 2007-2009 XK/XKR's connect the smartchargers to the method they feel most comfortable with. Chargers other than the CTEK brand may work differently. I have complete confidence that my connection using specifically the CTEK 3300 is safe without any fear of sparking or creating an explosion. It has been engineered for safety. Premium automobile brands have choosen the CTEK brand for their private labels to sell to their respective end users. Jaguar fully endorses the CTEK brand and sells them with the Jaguar logo, as does BMW, Mercedes, Aston Martin, Lamborghini, Maserati and so many other brands including Rolls Royce.

Be sure to complete a full inquiry with the manufacturer of any smartcharger before hooking one up.

This topic of smartchargers and making connections has had vast discussion on these forums, especially the CTEK brand.

 

Very true Richard.

I too use the CTEK 7.0 and I have mine connected directly to the battery terminals using the ring terminals supplied.

There are always people who will err on the side of caution and there is nothing wrong in that, however, I do not like the croc clip method as they can easily be knocked off.

 

I connected my CTEK extension lead directly to the battery as well. During the installation it is basically two unconnected wires so no danger of spark. I then plug the CTEK in to the extension lead before powering it on.

The attached is where Jaguar recommend attaching the remote leads on the 5.0L cars. The positive wire goes on the battery and the earth on a remote stud.

 

And let's not forget, the smart charger that Jaguar sell, is a CTEK with a Jaguar badge on it.

 

Richard,

I just wanted to point out that your advice (as well as CTEK's) is contrary to the 2009 model year XK/XKR owner's manual. Nothing personal, just stating a fact.

I've used the alligator clips for years on my remote battery terminals and they have never come loose.

Until Jaguar changes their owner's manual, I'll continue to keep my smartcharger connected to the remote battery terminals. Doing anything contrary to the owner's manual may void your warranty and absolve Jaguar from any responsibility.

Your car, your choice.

Stuart

 

Do you guys think you might be differing on the manual terms?
The manual refers to booster cables (aka Jumper cables) which we all know can spark, as opposed to the smart charger that Richard is using which is NOT a booster, and if not connected to a power outlet, would not spark.
Nor is it 12 "equipment" as it is nothing but a couple of wires when connected to the battery. I would think the manual is rightly referring to the act of connecting where a spark can occur, as the smart charger is not connected and disconnected at the battery it is really no different from the remote terminals provided by Jaguar.

 

To paraphrase Bill Clinton: "It all depends on how you define the word "booster" ".

To me, any device that delivers electricity to a battery is a booster, even when it is not plugged into an AC outlet or connected to another battery.

As I said, your car, your choice.