High resistance power drain
Senior Member
Joined: Oct 2009
Posts: 328
Likes: 38
From: Michigan
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.
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.
Veteran Member
Joined: Apr 2010
Posts: 7,657
Likes: 3,019
From: Arlington VA USA
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.
Senior Member
Joined: Oct 2010
Posts: 747
Likes: 307
From: Near Charlotte, NC
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.
Senior Member
Joined: Oct 2009
Posts: 328
Likes: 38
From: Michigan
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.
Member
Joined: Sep 2010
Posts: 95
Likes: 6
From: S.F. bayarea
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!
Senior Member
Joined: Nov 2008
Posts: 944
Likes: 133
From: Chicago/Southern Wisconsin
Float charging
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.
I use a similar set up with a solar charger for my boat and PWC batteries rarely have battery problems.
Senior Member
Joined: Nov 2008
Posts: 944
Likes: 133
From: Chicago/Southern Wisconsin
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.
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.
Junior Member
Joined: May 2010
Posts: 14
Likes: 0
From: san marino
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
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
Senior Member
Joined: Mar 2013
Posts: 148
Likes: 36
From: Rio Grande Valley, TX
Any fix
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?
Veteran Member
Joined: Dec 2011
Posts: 6,278
Likes: 690
From: Limousin, France
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?
Is there a big spark when you connect the battery terminals?
Senior Member
Joined: Mar 2013
Posts: 148
Likes: 36
From: Rio Grande Valley, TX
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.
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