My 2007 XK 4.2 is in (almost) daily use. 136k miles and mostly good but she’s developed the bad habit of fully discharging if left to her own devices for a week or more. I do remember seeing a post a while ago, saying that a certain part is the favourite for causing this problem………but can I find it?! Directions to that post would be most helpful please and all other suggestions gratefully appreciated. Battery is only 18 months old and journeys are seldom shorter than 10 miles or so, so charging should (?) be ok.

 

I have the same problem with our 2006 XK. I think the discharge might be something to do with the alarm sounder which no longer has a functioning battery so is drawing on the main battery to try and keep it charged. However, I'll also look forward to information about what to do to fix it.

Richard

 

Threads about
quiescent current
have lots of useful data & ideas.

Some are about other jags but can still be very useful.

 

True enough, the quiescent drain should fall within specs. The specs are in the workshop manual.
But... is the battery just old?

Also, in the modern age, think of an alternator as a "maintainer" not as a "charger" and you'll be happier for it.
(As in "Why" do so many cars now come with a factory battery maintainer installed?)

 

I use the 2 amp trickle charger that is easily installed by the taillights. When the battery is full the charging light turns green.
Good in the winter months.

 

When I checked mine years ago the drain when everything settled down was around 6 milli-amps. I've never needed a CTEK maintainer, though I do use one on my boat.

 

Just bought a 2007 XK that had a battery drain issue. One thing I notice right away is that the Audio system can be powered up with the ignition off. If you aren't playing a CD, radio station and have no background noise from the speakers it is easy to leave it on. The other reality is that every relatively new vehicle has computer systems that drain power just sitting there. This necessitates the use of a Batter Minder, especially in storage for any period.

 

Not entirely accurate. The audio system may only be enabled if the vehicle is either running, in "ignition mode" or in "convenience mode". If you shut off the engine, the car remains in convenience mode for 15 mins.
As my garage is always locked, the cars are not locked. That way the alarm systems are never enabled thus reducing the quiescent drain well below the allowed 35mA allowed value.

 

Waitaminutethough.......
My wife refuses to open her door until I open mine because the alarm ALWAYS goes off if the smart key isn't within range of the door. Even with the car unlocked and the alarm not active. Misnomer I guess, because obviously the alarm IS active if it goes off.
Maybe two stages of alarm triggering? I dunno, but it happens as I describe, every time.

 

I understand, the response.
And I do have the same outstanding question, going on 18 years.... (how did that happen??)

The claim that active monitoring is enabled by the car locking procedure...
and then... monitors the door hinges.
What's peculiar:
"The CJB automatically arms and disarms the active anti-theft system when the vehicle is locked and unlocked after successful confirmation that a valid remote handset/smart key has been used."
And yet, my quiescent drain is in the order of 10 mA...
So, I bow to those who know more ;-)

 

I had the same problem on my car, I renewed my back up alarm sounder and all my electrical problems disappeared. If the sounder does not beeb on double lock or the siren doesn’t sound when the car alarm is activated then your sounder needs replacing as the car is trying to charge the sounder batteries constantly but obviously they won’t charge. This is just my personal experience my car would drain the battery with in 3 days and now it will sit 4 weeks and start easily. Tommy

 

Glad you got that sorted. Mine sits for 3 months at times, no issues.

 

and mine would be dead in one week!
No sounder etc in the USA version I own.
WJ

 

[Walked out to the car this morning, opened the door, sat down, pushed the audio button, stepped out, shut the door let the CD play for over 20 minutes. Not sure how to respond to your claim.

QUOTE=guy;2868148]Not entirely accurate. The audio system may only be enabled if the vehicle is either running, in "ignition mode" or in "convenience mode". If you shut off the engine, the car remains in convenience mode for 15 mins.
As my garage is always locked, the cars are not locked. That way the alarm systems are never enabled thus reducing the quiescent drain well below the allowed 35mA allowed value.[/QUOTE]

 

@Excalibur2012 oooopersssss........ Let me fix that for you:

 

I’m confused. I read earlier that the car should always be locked, even in the garage to prevent battery drain. Now, we’re saying don’t lock it to reduce drain?

 

I checked mine years ago, it was 6 milliamps after some minutes - I can't remember if I had the car locked so I can't comment on the alarm draw.

 

Have read a few threads that agree you should ALWAYS double lock your car...less drain than just shutting the door...

 

Well, the workshop manual lays out the shutdown process and timings. And my car sits for3 months…

Cheers!

 

Don't have one..

can you give me a brief synopsis since there seems to be some debate on this issue?

Never had an issue when my cars were young..

Now that I have one 17 years old........with a built in C-tek...

replaced alternator and battery..

all seems good 2 months later..

but very curious on the reality of the situation...