XK8 / XKR ( X100 ) 1996 - 2006
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High resistance power drain

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  #21  
Old 02-23-2011, 07:12 PM
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I don't know for certain about Jaguars, but it is not unusual for modern cars to have multiple levels of "sleep." It could be something with the security system, or with the cellular phone, navigation system, etc. On GM cars the older Onstar system did something similar, shutting down to a lower current draw state after an hour or two.

Not that it applies in this case, but I remember one oddball case where the vehicle battery would die at a persons place of work, but not anywhere else. It turned out there was a broadcast tower nearby that was close enough to the remote entry keyfob frequency that the vehicle stayed awake "monitoring" the keyless entry system.
 
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Old 02-23-2011, 07:53 PM
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Actually, each electronic module goes to sleep individually based on what it is doing, what outside conditions it sees, and what traffic it sees or is generating on the internal commiuication network. Because there are so many variables, it may not always seem deterministic.
 
  #23  
Old 02-24-2011, 09:33 PM
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Originally Posted by Andy94SC
I just took a quick peek, and it looks as though there is a main relay at each fuse box that powers that fuse box. You should be able to pull each of them to eliminate each fuse box and save pulling each fuse until you narrow it down.
The Battery Power Bus bypasses these relays on each of the five fuse boxes and feeds directly to some of the fuses (unswitched, that is not switched by the ignition switch). The remaining intermingled fuses are indeed switched by that box's control relay.
Hopefully, in the next couple of weeks I can share some finding and a fix for my particular drain. I would like to see a sticky someday that list our drains.findings, and fixes.
 
  #24  
Old 02-25-2011, 04:44 PM
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Originally Posted by Dr. D
The Battery Power Bus bypasses these relays on each of the five fuse boxes and feeds directly to some of the fuses (unswitched, that is not switched by the ignition switch). The remaining intermingled fuses are indeed switched by that box's control relay.
That makes sense. The fuses powered by the relay couldn't drain a battery anyway now that I think about it, unless the relay was stuck on.
 
  #25  
Old 02-27-2011, 03:19 PM
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Sounds like every XK8 owner should have an AC battery charger to extend the life of the battery. Way better than keeping a damaged battery in the car. I just charged mine overnight and it seemed to idle smoother and drive better!
 
  #26  
Old 02-27-2011, 04:22 PM
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I wired up a remote access plug to make it easy to hook up a float charger and use it when the car will be at rest for a few days - especially in the winter. Easy access wihtour having to pull everything out of the trunk makes it a lot more likely that I'll keep the battery charged. Just be sure to keep the end of the plug capped to avoid an accidental short...

I use a similar set up with a solar charger for my boat and PWC batteries rarely have battery problems.
 
  #27  
Old 02-27-2011, 04:30 PM
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Originally Posted by Andy94SC
Tracking down a current drain can be tricky on modern cars with all of the software controlled modules. What happens when you disconnect, and reconnect power is that sometimes the modules with activate when power is connected. They shut back down when they determine the rest of the vehicle is not powered up, but it can take some time.

This happens when you pull and reinsert a fuse, and when you disconnect and reconnect the battery. Sometimes the battery reconnecting will activate enough things to pop the ammeter fuse.

To help with this I install one of these on the battery negative cable;



Then with the switch closed, connect the ammeter across the switch. That way when you open the switch the ammeter is already completing the circuit, so the current flow is not interrupted and the modules stay asleep.

Then you can get to pulling fuses to track down the draw. Just be aware that when you reinstall them that might wake something up, and the current draw will look higher than normal until the module shuts back down.

As a bonus, if you can't track down the drain, you can leave the switch in there and easily shut the battery off when the car is not being used. Draining a battery dead more than a couple times ruins them so they will not hold a proper charge.
I just "fixed" my neighbors Mercedes fitted with one of these battery switches. In his case I had to really torque the nut to get it to properly seat on the post - the gold material isn't very flexible. The real problem, though, was an intermittant connection within the switch itself causing random, momentary, faults. If you are going to go this route, forget the switch and just pull the cable.
 
  #28  
Old 03-27-2013, 10:52 AM
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I have a ? For you smart guys a out My 2001 xkr. I removed a seat
To work on the headliner. Left it unplugged for 3 days
Then found my battery dead. Any chance the memory function
( or "feedback") could have caused this?
Thanks in advance
Xj13
 
  #29  
Old 06-24-2013, 03:44 PM
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I am experiencing the same battery drain but at a faster rate. Like within an hour it drains and I just bought a new battery. What I do remember noticing was that my battery gauge was going lower and lower last week until the car totally died cause of the battery. I just ordered a new alternator cause the local auto parts store tested the alternator from the battery and they told me it was not getting charged. I also remember the wipers activating when I installed the new battery. Maybe the auto mode for the wiper is draining - I will check that out. Also - I installed some new led parking lights and I have noticed the thread where a member removed the 10A fuse on the headlights and that reduced the drain. I have two possible areas to check but did anyone else find a solution?
 
  #30  
Old 06-24-2013, 08:34 PM
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I'm only experienced with American iron, but has anyone thought to check for short or diode problem in the voltage regulator? I believe the regulator is inside the alternator case.....
 
  #31  
Old 06-25-2013, 05:29 AM
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If a new battery is going flat in 1 hour you're risking an electrical fire - you must be drawing 100 odd amps . I just can't see how you can draw that much current.
Is there a big spark when you connect the battery terminals?
 
  #32  
Old 06-26-2013, 01:13 PM
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Default fuse box

Took out all the fuses from drivers side bonnet area one by one and put them back. The drain has stopped. Not sure it why. My battery is still marking a little low so Im having the alternator replaced today.
 
  #33  
Old 06-26-2013, 09:57 PM
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Alternator installed. All is good. Back on the road!
 
  #34  
Old 06-27-2013, 07:42 AM
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Glad to hear it!


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