Having owned two previous Jags, S-Type and XF and never had any Battery problems, what is different about the XK that causes the power drain?

 

The XK has a LOT of stuff running while in "Stand By" mode. If the car is parked and DOUBLE-LOCKED, the drain will be less, but still more than you'd think.
All that said, a lot of XK owners use battery maintainers, such as the CTEK model. Search the forum for CTEK and you will find a lot of information.
Also, an AGM style battery is a good thing to have vs. a lead-acid battery.

 

If you think the XK(R) is power hungry you should try the XJL! I have made current draw measurements on my XJL and they were eye opening! Forgot the exact values but, things like opening the door and waking the XJL's electronic dash display, center touchscreen and associated processors, I read around 17 Amps. When turned on the sound system that value increased to close to 26 Amps.

In the XKR I did not make similar checks. The only checks I made were for an unexplained sudden drain of the battery when the battery went from fully charged to total discharge (to about 3 Volts) in less than two days of parking. What I had found that when you shut the car down and lock the doors, the electric system will power down in stages. For so many minutes it will continue to draw close to 9 amps, then step down to 2+ amps, followed by an other step to 1+ amp and finally down to the normal 0.04 amps. My problem occured when the last stage failed to shut down (infotainment system) and drained the battery. Hopefully addressed by a software update...

Once the car shuts off in a normal manner (0.04amps or less) the battery should hold up for extended periods. I left it without any external charging for 3 weeks during a recent vacation and the car started fine. Thus, the key thing to look for is to lock the car and MOVE the FOB at least 30 feet away so that near presence of the FOB will not keep waking the computers.

 

Keep in mind that many XKs are not daily drivers.

Repeated moderate to deep cycles of sitting for days or weeks with the normal standby drain will kill a standard lead-acid battery fairly quickly. An AGM battery is designed to handle this situation.

 

I'm intrigued by this and comments suggesting putting a battery keeper on when left for a week or two? Seriously would you guys not suggesting leaving one at airport for 2 weeks?

 

On a working car, it'll be fine.

The snag is that some are not really fully working, sometimes due to add-ons like chargers for phones, music players, remote starters, radar detectors, etc that don't allow the car to shut down.

If you measure the current after about 30 mins and it's well under 100mA, probably under 50mA, then all should be OK. Only a failing battery would then be a problem.

 

As long as the car is double-locked and alarmed, it should do OK for two weeks as long as you have a good battery.
Me, even though I DO have a good battery (not AGM yet, on the list), I'd probably want to take a jump-box and keep it in the boot, JUST IN CASE. Or maybe a set of jumper cables, though I'm not sure about the safety of jumping modern cars with a billion computer chips.

 

It's hard for me to comprehend this battery drain issue. I had an 05 XJR followed by an 07 XK and never had an issue on the original batteries. Both were daily drivers, more or less, doing about 5k a year.


I sold or traded both at 60k and 50k respectively with the original batteries. No Winters to speak of as both cars lived in central FL. Perhaps not too hot or not too cold Goldie Locks. WTH ? Am I the only guy on the planet with this kind of luck?


I will say that neither car ever sat for 2 weeks.

 

Andy - here is the math for your question:

Standard Jag battery capacity = 90 Amp hours.

Assume that we are starting with a fully charged battery. Shut it down, lock the doors. After a few minutes (12-15) the discharge should drop to 0.04 amps.

0.04 amps x 24 hours = 0.96 amps. Let's say we discharge 1amp/hour per day.

In two weeks, or 14 days, that should only amount to a 14 amp/hour discharge from the available 90 amp/hour. Plenty left to start the car.

Like I mentioned above, I left all of my Jags, the XKR the XJL and the XF off the charger while I was away on multiple 3 weeks vacations. Every car started on its own upon my return. The lowest voltage read that I had seen was on the XF after 3 weeks was 12.1 volt, an indicated 50 percent discharge. Probably due to the fact that it has a battery that is now close to 3 years old and the battery may not have been at 100 percent due to my wife's short distance driving routines. Both the XJL and the XKR have newer batteries.

 

I go overseas for a bit over 2 weeks a year and leave the Jags in the garage. I've never had a starting issue on my return. I cant say the same for myself though, I find it dreadfully hard to start after a holiday.

 

The thing with the XKs is that they should be locked AND alarmed, that way everything inside shuts down faster and more completely.
I've had mine in the garage for over three weeks before, locked and alarmed and everything was fine. Another time it was unlocked in the garage for five days and the voltage drop was enough for it to not start. Just a few minutes on the charger and all was well.
So what I say is.... Double-Lock and Alarm your cars! Even in the garage!

 

I did not think that you could lock the car and Not alarm it. Doesn't it alarm automatically when you lock it?

 

There are two stages of Lock and Alarm on the XKs.
From the User Manual...
Press and release the lock button to lock the vehicle and arm the alarm.
The doors are prevented from being opened from outside of the vehicle. The doors can be unlocked and opened from inside the vehicle. The hazard warning lamps will flash once as confirmation.
Press the lock button twice within three seconds to double-lock all the doors and set the alarm system to provide the highest level of security - use this method whenever possible.
Note: When the vehicle is double locked, the interior door handles are immobilised.
The LOCK BUTTON can be either on the Smartkey or on the Door Handle. The first push folds the mirrors (if so equipped) and locks the doors. The second push has an audible BEEP. That's the double-lock and alarm.

 

What the heck? That's the dumbest system I've ever heard of. Why would I want to only lock my car halfway??

Either way, good to know!

Now I'm tempted to have my wife double lock me inside the car!! Or maybe the other way around!

 

This "double lock" thing has always confused me. I routinely press the button on the door handle ONCE and the doors lock, the mirrors fold in and the red light on top of the dash starts to blink indicating the alarm is also on.

 

I wonder if this is why so many Jag owners have dead battery issues. Maybe they aren't double-locking the car, which prevents the car from going to sleep and drains the battery. I certainly never double-locked the car because I didn't realize it was a thing until reading this thread!

 

I've only been single locking I guess. Haven't had any issues yet but it looks like double is the way to go.

Mine is a daily driver about 6 miles each way so I picked up a CTEK 4.3 to throw on the car for the weekends and peace of mind. I also have a Blue Fuel Pack I got at Napa in the trunk just in case of a no start. Main reason was shortly after getting the car I was doing a wash and detail for a few hours and it drained the battery. Car wouldn't start and dash lit up like a Christmas tree. Now when I detail at least I can connect the CTEK to maintain the battery. Prefer that to letting the car run in the driveway.

When I bought it I was told a new battery was installed but when I installed the CTEK I found the battery looks new but why it would it look any other way where it's located. It's a Interstate MTP-93 so lead acid and whoever did the install never scratched out the little dots to let me know when it was actually done.

Put an AGM in my 97 but never had battery issues with that one. When this one is ready I'll do the same.

 

The security system is market specific. I thought the US cars just had perimeter sensing and an immobiliser which should activate at first push of the remote button? You can tell if that is the case because the red led on top of the dashboard should start flashing.

My ex-Japan 07 XKR has that (no interior sensing) and if I 'double lock' the car with the window open I can reach in and still open the door with the interior handle.

The alarm then goes off but the handle isn't disabled. Deadlocking tends to be a European thing.

It does have double unlocking but that just dictates whether everything is unlocked at the first press or just the drivers door and trunk and that can be enabled or disabled from the touch screen or by pressing both lock and unlock buttons at the same time for 4 seconds or so.


The electronic copy I have of the US 2011 XK just says this:

Press and release the lock button to lock the vehicle and arm the
alarm. The doors are prevented from being opened from outside of the vehicle.

The doors can be unlocked and opened from inside the vehicle. The hazard warning lamps will flash once as confirmation.

Lock confirmation
If you are uncertain whether the vehicle is locked and armed, press the lock button again. An audible confirmation will sound and the hazard warning lights will flash to indicate and confirm the current lock status.
Note: If the vehicle is not already locked and armed, pressing the lock button will lock the vehicle.

 

Interesting, I hadn't caught the double lock detail in the owners manual. I can see the safety reason why you wouldn't always want to have the internal locks deactivated.

 

Wow that is new news to me. Amazing with all these threads on the battery going dead and making sure the car is locked that this double locking item was not mentioned before! So I assume that if you only press the lock button once that the car is not fully alarmed even though the red security light flashes and the battery is draining more than if double locked?