Your unfortunate experience does not represent the majority, so I’d continue to find the defect in yours. Meanwhile, keep something like this with you, just in case….

BuTure Booster Batterie Voiture 5000A, 26800mah Portable Jump Starter (Jusqu’à 10l Diesel Ou All Gas) Démarrage De Voiture avec Grand Écran LCD,Lampe à LED,Pinces Intelligentes

https://www.amazon.fr/BuTure-Batteri...s%2C167&sr=8-2

 

Thanks a lot for that Tip . I thought such thing would be practical but totally ignored it exists.
To be honnest the thing that scares me the most is not the car not starting... but the christmas tree dashboard who suddenly decide on the highway that the car should stop there...and nowhere else...

I'm not sure according to the readings on this forum and others that the electric troubles are the minority...I would on the contrary tend to think it's the cars with no electricity management who are the exception...at least for the 4.2L .

 

I have suggested this hack before on an S-Type that we just never could find the current drain source. I do think that's your problem and they can be hugely difficult to find too!
He installed a battery cut off switch and simply cut off all connection to the battery when the car was off. Not great and it is a hack plus all the memory stuff like the windows is lost. But it was his only car and a daily driver so he had to figure something out. Desperate solution for a desperate problem I guess!
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This would be a solution for some without mains power for a CTEK or equivalent maintainer:

https://www.batterystuff.com/battery...2v-promax.html

 

I used such an automatic battery disconnect when the battery dropped below 12.2 volts on an older F150 I had which had an intermittent problem. It only disconnected about once a month, but holy hell it saved me at least several times from being stranded.

 

I owned an '07 4.2 XKR for 6 years and have had my '10 XKR for the same amount of time. I could tell when the battery on the 4.2 was getting low because the logo would stay on the touch screen for a lot longer when the car was started. I have never experienced that with my '10 XKR so presume they improved something.

 

Clever solutions here. Will definitely look for these gadgets and let them in my parking box.

But to me the most boring thing about the XK battery trouble is not that the car won't start...I would have prefer this as solutions exists...it's that it will start blinking like a christmas tree (Green and red ,right?) if the battery get low while driving and will show scary things on the dash... Typically if you use it for shopping or short city commute, it'll drain...( Even worst if you take the roof off and back...)and you'll get troubles...That's why I thought having a bigger alternator might help.It would recharge the battery faster for short drives , if I understand how it works. Isn't it?

 

Thanks for posting those automatic battery devices! They are exactly what was needed if the current drains can't be found and stopped. Much better than just a manual switch.
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That doesn't sound like a battery problem, sounds like alternator or some oxidised earth points, any of those'll contribute to the demise of a battery. I'd start monitoring/recording OBD data, that'll help narrow it down.

 

Yes, simply cleaning battery terminals may help resolve battery issues.
I once "cured" an uncurable 1971 VW Type 3, my wife's favorite vehicle of all time, that had corrosion where the wire met the battery terminal.
Life was good excellent when she thinks that you are her hero.

Since our XK/Rs are aluminum and in service 10 to 17 years as of 2024, oxidation of grounding points is a logical concern.
Has anyone investigated or discussed at length the grounding point issues?

The single wire LIN communication to the alternator actually uses ground as a reference.

 

Regarding Denso and Bosch as a possible source of electronic gremlins:

Digging into Jaguar parts catalogs to understand Denso/Bosch, the key is the crankshaft sensor.
Denso used the magnetic sensor. Bosch used/uses a Hall-effect sensor.
Beginning 2010, all supercharged Jaguars (except XK but including XJ) used Hall-effect sensors, thus Bosch ECM.
Beginning 2016, all Jaguars (except XJ) were SC, thus Bosch.
XK never made the transition to Bosch.
2016 model year also marked the transition to Pathfinder.

XK electronic control module revisions:
The first gen XK/R (4.2L) part numbers differ from second gen more that second gen to third gen.
XK modules often retained the same part numbers with revision letters.
Same part numbers with different letter extension are sometimes backward compatible, sometimes not.
Take XK smart junction boxes for example: The FSJB changed in 2012 to accommodate the face-lift and revised headlights. It is not interchangeable with the 2010-11.
The RSJB was revised the same year to accommodate the reverse, backup camera. It is believed to be backward compatible. The 2011 RSJB is not forward compatible.

Conclusion: Denso/Bosch is not an issue for the XK. XK is Denso. F-Type is Bosch.

Note that the XJ NA remained magnetic sensor, therefore Denso to the end, 2019.
The XJ SC changed to Hall-effect, therefore Bosch with the other models in 2010.
So, from 2010 to 2016 there were two types of crankshaft sensor and ECM electronics in JLR service.

Difference between Magnetic and Hall-effect sensors:
The magnetic sensor is simply a wire coil wound around a magnet. The movement of the magnetic field disturbed by the reluctor induces a voltage on the coil. The voltage (and frequency) increases with the speed of the reluctor. There is a wide range of voltage out. Low speed may be difficult to detect, so a cam sensor may be used at low speed. Two wires out, self-powered, no V input required.

The Hall-effect sensor contains a solid-state electronic device that requires power. Since a common ground is used, typically three wires are required. The output voltage is stable, despite frequency change. Low speed response is very good.

JLR triggers on rising pulse for magnetic and trailing edge for Hall-effect.

The Hall sensor is superior for constant voltage and low frequency performance.

The magnetic sensor should be more reliable due to its simplicity. (Actual failure rates are unknown and may be very similar.)

As part of another project. I am considering a switch to the Hall sensor and reluctor. The XK Denso ECM should accept the Hall output because it falls within the expected crankshaft sensor input range to the ECU. Timing detected by the ECM would be on the rise rather than fall of the 4.5V remaining of the 5V input to the sensor. Supplemental power is required.to the Hall sensor.

XK software revisions or just simple reprogramming sometimes resolve what appears to be a hardware issues. This may be due to chronic low voltage.
Example, there are reports of reprogramming resolving TPCM malfunctions.

best regards,
Bill

 

I think the transition for the non-XK models was actually somewhere around the 2012/13 model year.

The parts catalogue seems to confirm that because if you look at the 5 litre XF, the first ECM was the C2P16956 which is also listed as for the XKR and XKR-S. From S61362 (2013MY) the part is C2D30319.

 

@u102768 You may be correct.
We have tried to draw conclusions for a wide range of models and years by reviewing the parts catalog.
The parts catalog has conflicting information between the general part description and the line-item descriptions.
The Denso/Bosch conclusions for models other than the XK/R are, unfortunately, speculative for years 2010 to 2015.
However, I think that we all agree that All 2007-15 XK/Rs have Denso engine control modules and touch screen displays.

If anyone has definitive information on which engine/models/years include Denso or Bosch, please post the info and source.

best regards,
Bill

 

I actually thought it was pretty common knowledge, especially for anyone who has tried to tune a Jag of this era.

Here is a post from Velocity AP:

https://www.jaguarforums.com/forum/x...2/#post2580432

 

@Bill400 Also don't forget the addition of the LIN bus to the 2012+ X150. Otherwise, with JLR's eyes on other platforms, the X150's retirement was likely set years before despite the massive facelift for the last generation (although interestingly enough, the R-S and GT share suspension parts, steering, etc with the first gen F-Type...)

 

Bill is getting into the minute details and what I find interesting is he has posted that even with the mass migration of Jaguar from Denso to Bosch for the ECM's and infotainment modules (The main controls in the car) it appears there is still a mixture of Bosch and Denso sensors and/or modules used though out the rest of the car?

I would have thought it would have been a whole sale change of suppliers when the change was made?
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Further review of ECM part numbers (as best I can find) we have:
C2D5480 5.0L NA Denso
XF 2010-12
XJ 2010-13
XK 2010-15
C2P16956 5.0L SC Denso
XF 2010-15
XJ 2010-13
XK 2010-15
C2D54092 (replaced C2D30319) 3.0L/5.0L SC Bosch
XF 2013-20 3.0L(16-20), 5.0(13-15)
XJ 2011-19 3.0L(14-19), 5.0L(11-13)

Restated, XFs are Denso thru 2012, may be Denso or Bosch 2013-15, and are Bosch 2016 and beyond.
XJs are Denso 2010-13, may be Denso or Bosch 2011-13, and are Bosch 2014 and beyond.
XKs are all Denso.
So, to compare XK battery drain to 5.0L XF and XJ, we may want to consider the model years of the vehicles.

Rephrasing the original question: Do XK/Rs experience greater battery drain than 5.0L, 2010-12 XFs or 2010 XJs?

To that end, Autozone provides a benchmark for battery voltage: attached.
and Jaguar quiescent battery drain: attached.

We expect a minimum of 12V to startup.
12.6V to 12V = 50% capacity.
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Based on a quick google search, H8 battery should store 90 Amp Hours (assumed new).
If we assume a perfect battery (12.6v) with no internal losses
and the XK draws 0.030A x 24 hr/day, we have 0.72Ah/day drain.
90Ah x 0.50 = 45Ah available for current drain @ 12V residual.
45Ah / 0.72Ah/day = 62.5 days
Therefore, if the battery won't start the car after sitting for 30 days or so, there is a problem.

For folks chasing the XK/R battery drain gremlin, the Battery Section of the Shop Manual is attached.

 

@jahummer The suspension and steering parts interchange is very interesting... the F-Type three-pedal assembly appears to be bolt-in to XK, and transmission as well. Though not likely of interest to the XKR folks.
Your mention of LIN Bus got me curious, so here is what I could find:

VIN B09097 to B32753 (Gen1) LIN use:
Battery backed sounder communication.
Start Control module comm
Paddle switches comm to IC
Cruise control comm to IC
HVAC air door motor control comm
Door Mirror control comm
Driver and Pass seat switch comm

VIN B32754 to B44940 (Gen2) LIN adds:
Rain sensor comm
Battery monitor comm
ECM to Alternator comm
TCM to shift module to TCM comm

VIN B44940 and up (Gen3) LIN adds:
AFS Headlamp control comm
Parking Camera guidelines comm

The LIN changes make the FSJB and RSJB different for GEN 1,2 and 3.
The FSJBs are not compatible forward or back.
The Gen 3 RSJB is likely backward compatible to Gen 2 but not Gen 2 to Gen 3 due to the camera LIN.

 

Well, mine is one of the very early ones (build year 2006)
And I just don’t have these issues many have. Mind you, I replace the battery at first signs of degradation, I do not use a maintainer, and she stays in the garage, unlocked (alarm not armed) for months on end.
Also, all manageable systems get shut down before shutting off the engine. (audio, interior and exterior lights, climate control, touch screen) and don’t get turned on until she’s running smoothly (about a minute)
As many of us know… “its always the battery”. So, why bother maintaining a degraded battery?? Just change it already.
@Bill400 , well done. Many overlook the state of a battery with a capacity of 12.2 v. I change mine long before that.
Cheers everyone!

 

@guy Thanks,
The vast majority of electronic problems with our cars is correctly summarized: "It's the battery!".
No OEM voltmeter is provided. Xks tend to be garage/driveway queens, not driven daily, so low battery voltage is likely.
For many folks, the battery test is start/no start. When battery voltage is low but sufficient to start, the problem goes unnoticed until it presents itself as a module fault, seemingly out of the blue. The problem is accentuated, I believe, by marginally performing new batteries.
If a battery is less than 100% charged (say 12.4V) when installed, will the battery monitoring system (BMS) of 2010 and newer models prevent it from ever becoming fully charged? My understanding is that the BMS will properly reset over time. Maybe too long and battery never recovers?
The service manual battery section, previously attached, is good but maybe it's time for our brain trust to cobble together a proper document.