It seems that the 2007-15 XK and XKR are more sensitive to low battery problems than are other Jaguars.
Got me to thinking: has anything been done on subsequent models?
That lead to the Voltage Quality Module introduced around 2016 for ECO-Start vehicles.
Both Jaguar and Ford recognized that repetitive re-starts created a low voltage problem that affected control systems and introduced the VQM and other features to combat the problems.
An F-Type diagram is attached for those interested.
Maybe a DC/DC converter to maintain and clean-up our power?

 

Easier to use a CTEK and change the battery more often. I don't see the VQM being easily adapted to our Jags.

 

The Voltage Quality Module illustrates the power quality concept but admittedly, as designed for the Eco-start, would not be applicable to our XKs
However, DC-DC converters and related power quality technology have become commonplace. Applied properly, it could improve control system reliability and possibly extend useful battery life. Might be worth looking onto.

 

Bill, I think I'd research quiescent drains first. Also common in the X150

 

Unfortunately, for DIYs, changing the battery is no easy task nor is it inexpensive. Moving 70lbs around in a tight spot is not a walk in the park.

 

I’ve not found the X150 to be any more sensitive than any other, even current, JLR vehicles or any other European made vehicle.

 

I went to test drive a C7 Corvette when they first came out, but couldn't because the batteries in the two they had were both dead. I went back the next day. Not a fun vehicle to drive.

 

A comprehensive investigation into the "normal" quiescent drains is an excellent idea. Leaving the doors open while you detail the interior shouldn't result in a dead battery. I wonder if the F-Type improved on that with their quiescent module? Darn it Sean, the list of fun things keeps getting longer!

I totally agree that battery change is a PITA and just under $200 for DIY as of 12/23. A bit easier in a cabriolet with the top propped mid-way open to expose the battery compartment.

Not experienced the battery issue with other Euro cars, so appreciate the comment. I have found X-Types to be no problem with battery drain, even when left unattended for extended periods. The most recent battery replacement in the XK sent a German made battery home after two years and at the beginning of a cold snap.


I suspect that battery quality control is hit or miss. Sometimes new batteries are sufficient to start our vehicles but not maintain minimum control voltage under starting conditions. We have seen the discussions on the forum: every conceivable electrical gremlin due to low battery voltage, probably a negative "spike" during start.
If a conditioner of some sort was provided to bridge the negative spike during starting, and possibly hold the voltage to a closer tolerance, say +/- 0.5V during normal operation, would our "on-board computers" function better?
Remember "un-interruptible power supplies" for desk-top computers?
Not a problem for laptops because ...

PS: If any modules include electrolytic capacitors, close voltage regulation would be a good thing!

 

P=IE. And there are varying types and qualities of batteries.
Put the specified battery in your vehicle and ‘ta da’ there should be no issues. Leaving the interior lights on, stereo going and systems powered up for an elongated period of time, without a means of electrical generation applied is asking for trouble… on any modern car.

Please don’t mess with the location of the battery in my car. I quite like the balance of the car, as is.

Many think of stop-start technology as a simple means of reducing fuel consumption. I humbly disagree. Its all about reducing smog in built up areas. (Flying into any large metropolis and looking out the window should drive the need for such technology on its own). The number of systems which needed re-engineering for this solution was not insignificant. Too bad these cars were engineered before that time.

Happy new year, Everyone!
G.

 

In case this might help, most recent high range Mercedes and BMW uses 2 batteries...It really helps as the problem with the XK is that low batteries leads to severe troubles such as sudden car stop while driving...
It'll never happen in an SL...there's one battery for the engine, and one for the gadgets...
To me the whole infotainment/car management system is really a pity in the XK... mixing them both was really a trouble source..
I wish a passionate electro-technician would rewrite the car management and take all the bugs off...maybe in 20 years when it'll be a sought after collector car.

 

Thanks Guy,
Interesting thought ... the XK/R battery location would seem more suited to RHD vehicles ... but, I agree, let's not go there.

It's different strokes for different folks ...
There are those who "tune" for horsepower and shift points,
others change tires and suspension for handling.
I read about electrical gremlins and think of
"souping up" XK electronics for reliability.

Best regards,
Bill

 

Rhys Morgan is doing just that! He's working on an XF in the UK. Since the XF and the XK are kissing cousins, electronically, Rhy's work should be readily adaptable to the XK.

Bill

 

The double battery system was also used by Jaguar until 2015/16, but the second battery was to supply the start/start system, not the “gadgets”. Many, myself included, simply disconnected the (irritating) stop/start system by disconnecting the second battery. Doing so does not in any way affect any system other than the start/stop. All the gadgets (and my car has them all) continue to work perfectly.

 

Agree balance. Thanks for the explain on smog being the reason stop/start introduced. Some small fuel consumption reduction/vehicle (if it does) might improve corporate average and help compliance w/ mpg requirements.

 

@Bill400 . That's very interesting.
I'm sure this kind of research is the future of auto collection (and that's even much more eco friendly than producing new fully electronic 2,4T cars).
But... who's this Rhys Morgan? I made a search on Google and found nothing

 

I've keep reading about the XK and I think there's one thing missing in our talks.
Apparently the car is draining the batteries when it sits... BUT there's also another point o think about... Are the batteries fully recharged everytime we drive?
If the car was producing enough energy to feed all its accesories while driving + recharging the battery, when we stop the battery would be always fully charged... right?

So, isn't the original alternator too small?
Searching the web I found there's one american company making bigger alternators.

Do you think that would change something? Has anyone here tested such things?
https://www.power*******s.com/prodde...3979-250-HD1-9

 

I think there’s looking for a problem that isn’t there. The X150’s not as much of a power hungry electric consumer as some are making it out to be. Interestingly enough I’ve never had any unexpected electrics issue related to batteries that I can recall with any Jag I’ve owned, 6 to date. Even with the current X150 and minimal driving, the original battery lasted about 6 years without a maintainer, the second battery was perfect before I replaced it with LiFePo4. I do acknowledge some here have experienced unexpected drain issues, but that was not inherent in the design.

However with the Land Rovers I’ve owned, which are significantly more dependent on electric, even uprated batteries last only 2 years. I get mine manufacturer direct and told 2 factors contribute to their early demise, climactic heat and electrical demand from Land Rovers. Extreme cold can also affect battery longevity. Something then to consider, environmental.

And finally a sad reminder, as these age, the electrics (and plastics) are becoming more prone to failure. Lack of serviceability will likely keep these cars from collectible or classic status. True really, of any modern car. Remember, the classics and collectibles either don’t have any electronics and cheap plastics or there’s a significant aftermarket for support.

 

My only comparison is my 2010 XK to my son's 2014 XFR-S. He never connects any battery maintainer and his car sits for up to 2 months sometimes. Starts right up every time. I can not go even 1 month without connecting the C-Tek. Battery age on both cars is about the same.

 

Thanks for the F-Type experience feedback. If I understand the "delete", you removed the LIN connection at the VQM, leaving the remainder of the system intact. Don't know if that completely disables the secondary battery support to the gadgets described in the attachment to post #1.
The F-Type also has improvements to Quiescent Current Control, per the attachment.

best regards,
Bill

 

Sounds like a great opportunity to check and compare quiescent current draw.
If traced to a specific module, it would be good to know both hardware and software part numbers.
Is an accessory keeping the CAN bus awake?

Please provide details (both cars): Battery brand/age? Park inside/out? Ambient temp? Lock on park? Doors open to detail frequently?

Also, there are semi-defective batteries out there. I purchased a German made replacement battery, so I was sure that drain/related issues must be poor locking habit (not locking) or some form of current leakage. The latest battery purchase appears to be a big improvement.