Hi,
I would really appreciate your advise on a recent issue with my 2012 XF. Last week my wife noticed a "high pitch noise coming from the engine bay" when she started up the car. She then noticed the dashboard warning light saying "Battery Not Charging!" and so decided not to drive the car. I purchased a new belt tensioner, serpentine belt and alternator from Ebay and gave them to my local mechanic when I dropped off the car with him. Because the incorrect belt tensioner was delivered to me he was only able to replace the alternator and the belt. The trouble is that the "Battery Not Charging!" is still displayed. Even after the BMS was reset the sign is still showing. I have checked the voltage reading with my multi-meter of the big fuses in the boot, the two 250A and the other large ones. I checked the voltage before and after these fuses and the reading is just telling me the voltage of the battery, which is currently 10.7V.
The alternator is the cheapest new one that Ebay has offer and so I am wondering if perhaps this could be the issue. In hindsight, I should have purchased a Lucas one.
What are your thoughts, please?
Thanks in advance!

 

When you put a voltmeter across the battery, what reading are you seeing with the engine running?

 

Currently the battery is on charge as there wasn't enough power left in it to start the engine. Yesterday, my mechanic said that when the car was at idol, the reading on his meter was 11.4 but this dropped when he increased the revs

 

when purchasing a alternator of eBay always purchase a used oem one, don't get me wrong you can find a good new one but its very slim, so either purchase a new one from JLR ,or a used one from eBay , when it comes to accessory belts its best to get the JLR oem for correct fit, battery has to be reset with a good tool like SDD, Autel etc. ,now your BMS ALSO COULD BE BAD ,

 

This has been reported many times. The suggestion is to keep the OEM alternator and have it rebuilt locally.
Do you still have it?
.
.
.