@jahummer
Your point, and Sean W's, is understood to be " define the problem before proposing a solution...".
Hard to argue with that logic.
Would you guys consider collaborating on a guide for XK/R owners to evaluate their own systems that appear to be battery related?

PS: I'm thinking that a C-Tek should not be required for a vehicle parked for less than a month.

 

Agreed about the maintainer, didn’t get a CTEK until the second battery and didn’t use it all the time even with the car sitting for weeks at a time unlocked. Other members here have shared the same experience whilst others have stated otherwise. Most exotic cars require and include CTEK maintainers, McLaren and Ferrari are two of the most notorious for dead batteries, even with OEM lithium batteries.

 

This is an experiment I will not find the time to execute, sorry

Not sure of brand but both batteries are currently about 4-5 years old but similar behavior throughout the last few years so I don't think age is a factor. In fact, My XK is routinely on the C-Tek and his is never so I would assume my battery is in better health. Both cars are always parked in their respective garages, both in North Texas so ambient temps vary but both cars are seeing similar temps at the same time. Both cars are always locked and doors are never opened during downtime.

 

I didn't use a maintainer until after I tried to test drive a new C7 Vette that was dead on the showroom floor. I can't rightly remember if I had any problems before that or not. My last battery lasted just over five years before it showed signs of going bad.

 

There’s 3 versions of the X150, 2007-2009, 2010-2011 and 2012-2015. Perhaps one of these generations is more prone to this?

 

It has more to do with the year of the car rather than the model. Jaguar is a very small company and most parts are used across the entire product line.
What happened was Jaguar made a wholesale change of electrical suppliers starting in 2013 and up. They dumped Denso and went to Bosch.

If you look at all the electrical threads a vast improvement was made from 2013 on. My 2014 XJR has had zero electrical problems and I have never put the car on a charger. Nor do I lock my car in the garage and both key FOBS are within 20' of the car at all times. I just replaced my factory battery after 10 YEARS! It still was working I just got scared and swapped it out. I have never had a battery last anywhere close to this.

I have left my car at the airport for 6+ weeks and it started up fine and I just drove away!

Now I wish Jaguar had published all that was changed but it was such a huge change I think they simply did not want to draw attention to it? I mean what did it take for Jaguar to tell Denso to take a hike?? I bet a lot!
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Even so, there were 2 denso versions for the X150, 1st gen had one and 2nd gen had a different one. Then 3rd gen went to Bosch. There’s still plenty of 1st and 2nd gen owners reporting no battery drain or electrics issues, surely something else must be the cause for those afflicted.

 

Sure there must be something...
Because most of us are having the battery problem even with new batteries...So the battery is not the problem.
What would be interesting to know is if the car alternator is really charging the batteries while driving...

 

In the case of the F-Types with two batteries, it is not a matter of disconnecting the LIN from the VQM - that may be how the stop/start system is disabled in the later one-battery F-Types (2017-24). On the two battery system you disconnect the second battery entirely! In other words, you eliminate it from any part of the car’s electronics. I did this 7 years ago on my 2015 F-Type. Not a single electrical/electronic issue has ensued. But the irritation of the start/stop function ended immediately.

 

On the XJ I drove as a loner you could disable the start/stop after starting.

 

X150 never had a bosch control module for anything.

only notable thing that happened in 13 was on the xj and xf, panpag pcm and the old denso infotainment were retired.

 

Thanks Xalty for the added info. I am still researching all that was done as it's very obvious that it was a large change and made a huge difference.
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Thank you for the clarification. The F-Type electronics is clearly improved compared to the XK/R.

best regards,
Bill

 

I respectfully disagree with the assumption that a new battery is good, not a problem. More in another post.

Alternator output may be monitored using a simple digital voltmeter accessory that plugs into the cigar lighter socket.

best regards,
Bill

 

I was referring to this post:

Third gen X150 added LIN bus and something else was changed in the PCM but I don't recall. The F-Type always had Bosch. Panpag was retired with the X100.

 

The hypothesis: "XK/Rs are more sensitive to low battery than other models" failed to address the causes but attempted to propose a solution.

Backing up a bit: There appear to be two basic causes of "low battery" (voltage) for starting:
1. Parked vehicle battery drain due to quiescent loads. Jaguar introduced a dedicated module to address this issue in the F-Type (see post #1 attachment).
2. Defective or old batteries that do not maintain 12V+ when parked overnight, a week or so.

If the battery is sufficient to crank-start the vehicle, should the instantaneous residual voltage be sufficient for proper operation of the electronics?

The intent of post #1 was to propose that low starting voltage is likely a source of various control module problems. Since start/no-start is typically the criteria used to evaluate a functional battery, by extension, the residual voltage should be sufficient for control module operation.

A guide to battery, alternator and quiescent loads may be the appropriate first step.
I'm happy to collaborate with anyone interested.

 

Though 2nd Gen XK has LIN for Alternator, etc. You guys are clearly well informed. I for one would appreciate more details and happy to do the work if you point me in the right direction. Maybe a good addition to a collaborative guide?

Bill

 

Yes, of course you can do that. The F-Type also has a button that can disable the stop/start system but each time the engine is shut off (by the driver) the system defaults to the annoying stop/start sequence…in other words you have the minor fuss each time you start the car of having to shut off the stop/start system. Much more efficient to disconnect it once, and never again.

For the record, I generally don’t drive in “stop and go” traffic so any ecological benefit to the start/stop system in my car is essentially nil, particularly as the engine is labelled as an ULEV (ultra low emissions) engine. The ecological damage from just one rocket fired in The Middle East, just one drone strike in Ukraine or (fill in the name of any number of regions today) is far greater than driving a modern car for a year or a decade. The “save our planet” activists (whose work I support) are (strangely) absolutely silent on this form of pollution.

 

Bill, you’re correct, I’ve not addressed the premise for your thread. My Land Rover apparently has this VQM though I stopped using the ECO mode after the third start/stop battery replacement in 2 years.

I reckon you realise this could never be retrofitted to the X150. Yes there’re higher current output alternators, but charging’s not the issue.

I’ll defer to my first response, not every X150 have battery issues and a CTEK or equivalent’s likely the easiest and least costly solution for those concerned about potentially flat batteries.

 

I just installed the Ctek trunk plug... but when I'm in Town I don't have access to a plug!
I realise If I can't find a way to get electricity in my underground parking...I'll have to sell the XKR just because that's an almost electric car and needs to be plugged often...