Second time in a couple of months I have been away for work for a week and the car is completely dead can't even open the doors. Have to use the emergency key and jump start it. Car is so dead that it completely sucks a portable lithium jumper dead with no start. Eventually after I have had to directly hook my diesel truck battery to battery and let it sit and charge for 5 mins I finally get it to turn over and start.

Last time it happened I took it to the dealer and they checked the battery and say it's fine.

I also often get the low battery start car message.

There is something not right here, something is not properly shutting down when it is turned off but the dealer says all fine.

Anybody got any ideas?

 

Your post surprises me. I've left my car for 2 weeks at a time & it's started every time.

 

Have you got anything connected to the car - radar detector / dashcam etc? The dealer should be able to check the drain on the battery with the car switched off and troubleshoot from there.

For reference, I have left my car standing for 3 weeks with no problems.

 

You shouldn't be, there have been many posts on this exact same issue. I personally had the battery replaced and have been fine since. Mine was just after taking it out of winter storage so i'm curious if my battery tender killed it.

 

I know I'm sounding like a broken record here, but this scenario happens frequently and often is cured by disconnecting the battery for 10-20 seconds (if you have 2 batteries disconnect both). The energy control module needs to be rebooted.
And3rew, maybe you have already tried and it hasn't worked. Please confirm.

 

I also started a thread just last week on the same issue. There was a larger thread discussing it as well. I also went to the dealer and they said everything checked out. I tried what unhingd suggested, disconnected and reconnected the battery. I am happy to say that it worked! I just got back from an 8 day vacation and no low battery message. Before I was getting it every other day if I wasn't driving.

 

You're not the only one; the dealer replaced my battery. There were codes stored regarding vent malfunction and transmission problems due to battery/electrical problems. Press the dealer harder.

 

Like many have said, this could be a simple battery problem. It could also be that the car is drawing parasitic currents from the battery. You can test it with a multimeter yourself, or find a good audio shop to diagnose it for you.

 

Dashcam, but it is plugged into the cigarette lighter which is supposed to be off when the ignition is off.

 

No I haven't, will try it. I know where the main battery is, where do you find the second battery, convertible.

 

You don't need to worry about the 2nd battery. It only powers Eco mode.

 

Had similar issues with my old XJL. solution was to double lock the doors which shuts down the car completely.

double locking is by pressing the lock button on the fob twice

 

Most likely true, but just in case there is any crossover bleed, I would disconnect both at the same time. On the '14, the ECO battery is about 2 ft to the right of the main battery under the hidden trunk compartment.

 

I have my radar detector plugged into the cigarette lighter socket. I just checked again, and the cigarette lighter is HOT when the ignition is off. I always pull the radar cord out of the socket when I stop the car to mitigate battery drain, but simply turning it off would probably work too. Same for your dash camera?

 

Hmm, I will have to check again, the dash cam seems to switch off when the ignition turns off, but I will check again.

Went to the dealer today and they will be replacing the battery under warranty. We will see if that solves the problem.

 

The 12v in the center console is definitely not hot in my car when the car is shut down. However, it turns on when you unlock the car. Goes to sleep once you lock.

I haven't used the one in the center stack for this purpose however.

 

+1

 

I've noticed one thing on mine, when I have a battery problem, the hazard triangle stays lit even if the power is turned off.... so I noticed it yesterday again, figured I'd have time to connect battery charger and disconnect battery.... good thing I noticed it, we'll see if I have to do that window calibration again.

If anybody remembers off the top of their head how it's done, please add here...

 

Battery Tender pigtail installation below. It's as easy as screwing in a light bulb and takes maybe 5 minutes.

Trunk floor panels simply lift out, and there are no fasteners. The small red wire goes anywhere on the battery bus bar (remove the bus plastic cover). Mine is opposite the yellow wire. The small black (ground) goes on the same nut as the car's ground cable (bottom of picture). You can see the pigtail where you plug in at the top of the picture. Just leave the plug part exposed above the floor panels when you put them back in. They still fit flush.

CTEK or any other battery maintainer is wired the same.

Also FYI, my red triangle also stays on for 5 to 10 minutes after shutdown (haven't timed it) before going off. I've never had a dead battery or warning light in 2 years and have left the car off the battery maintainer for as long as 2-3 weeks.

 

Hold window down button until window is completely open, keep holding for 5 seconds then release. Follow the same procedure while closing and the auto up/down should work in both directions again.