I’m after some advice i brought my first XF (3.0 D) a couple of weeks ago and everything has be fine until last night. Started the car and everything was normal apart from the hardwired dash cam was not powered then after approx 20 seconds of idling the battery charge warning light came on. I tried restarting the car twice but the same problem. Had a look for loose connections or even a thrown belt but nothing obvious. I decided to risk the 4 mile drive home just on the battery however after a mile it started shutting down various systems until the whole thing ground to a halt with absolutely no power to anything. worryingly We tried to jump start it but when connected to the other vehicle all we had was head and tail lights came on and nothing else then started to smell something burning in the engine bay around the area of the alternator. We disconnected the jump leads however the was warm as if it had a dead short.

 

Would disconnect the car battery straight away. Then you need to run diagnostics. Sounds like start by checking if the alternator is fried?

Did you pull the fault codes from OBD?

 

You didn't say what year the car is? I had the stop start battery go on mine and it fried the alternator, which seems to be common when the start stop battery fails.
I got a "battery not charging" alert on the dash even though the main battery was ok and was holding charge. After replacing the start stop battery and the alternator the main battery started failing after a few weeks. Tayna are incredibly cheap and do next day delivery if your batteries have failed and ECP did a refurb lucas alternator.

I would also check for water ingress to your CJB and RJB as these will cause electrical gremlins.

 

Yes I disconnected the battery as soon as it was recovered to the garage. I did try to see if i could get any codes but there was no power to the OBD socket either

 

Sorry it is a 2011 luxury 3.0 diesel and is not fitted with start/stop. I did pull the covers off all the JB including the one in the engine bay a could not see any obvious signs of moisture present or any other obvious fault. Ive read about water wicking up the cable from the washer pump but I thought this only affected face lift models but will see i can disconnect the multi plug on the CJB for signs of corrosion, although what ever has happened I’m sure the alternator is toast due to the burning smell from that area of the engine bay