HI All really hoping someone can help me out here im completely stumped, So last night was driving my 2010 XF 3.0D and first the screen and clocks went off and soon after the car completely died, literally everything no power to any electrical device (lights, led's etc etc ). Tried to connect a jump starter pack and the fuse in the jumper pack blew, tried with a new fuse same thing it would appear that the car is totally earthed. Have now been towed, managed to find the gearbox release in the centre console) home and the battery is utterly dead (which i guess it would be since all the power seems to be going straight to earth. does anyone have any suggestions on cause or process to diagnose? I have now disconnected the battery and will try charging that separately but i doubt that a dead battery would completely earth the car. I have just had a look at the main junction board in the drivers footwell to see if there is any water ingress and nothing seems apparent. I have also read about the power terminal behind the wheel arch but not sure if this would cause this issue? Please help i cant even lock the car or put the handbrake on :-(. many thanks

 

Complete shortcuts on AGM batteries are very rare, but not impossible. Any easy test would be to measure the batteries voltage whilst disconnected from the car – given you have a multimeter. Set the Multimeter to DC / = and measure the voltage across the battery terminals. The values vary a little depending on the battery type, but as a rule of dumb anything between 12.4V and 12.8V is ok. 11.6V or less is fully depleted but still healthy. 10V or less is either deep discharged or indicates a shortcut in one of the cells. Deep discharged agm batteries can be recovered using AGM chargers, but if your battery is already older or reads less than 10V I’d not bother. If you read 0V, (and only then, otherwise you may destroy your multimeter) you can set the Multimeter to Ohm / resistor and measure again across the battery terminals. If you read 0 or almost 0 your battery suffered from an internal shortcut, and that’s where all the energy is absorbed.

Good luck

Chris

 

Hi Chris

Thankyou so much for coming back so fast, I shall try what you ahve suggested and see how I get on, gaain really appreciate the help

cheers
Jake

 

A 2010 XF has a 'normal' flooded cell lead acid battery, not an AGM. An AGM battery wasn't fitted to the XF until the 2012 MY with stop/start.

 

Hi

Following the advice posted by Chris Ive just taken the battery out of the car and tested the voltage accross the +ve and -Ve terminals and reading was 11v, I then put the battery on charge for 15 mins and tested again and its now reading 15.5V but guessing this could just be following the charge and it will eventually settle?
I also connected the slow charger directly to the car wiring to see if I could get any lights or sign of life but this just blew the fuse in the charger immediately.

Can anyone help me out with a next step? thanks in advance

 

Right, I forgot that. The test procedure works also for standard batteries though.
From what I read Jake already tested and to me this does not look like a battery issue.

Chris

 

Did you check to see if the car is charging from the generator/alternator? Be my first check if stuff started to die while you were driving.

 

Hi Rummy636

yes i would normally check the alternator too, I would have assumed that if the alternator was at fault then putting a jump back to the car would have at least put the interior lights or dash on though, since the car would be getting power through the jump?

Thanks

Jake

 

Not if the alternator has an internal short - which you should be able to test for if you disconnect any wires from it and measure from the large +ve terminal to earth.

 

You need to take it one step at a time.

Connecting a battery maintainer to the car with no battery then the car will be drawing much more current than the 5A or so that they can provide and youbprob just blow the fuse in the charger

So - step 1 get your battery working. Put it on the battery charger for 24 hours, take off and measure voltage. See if it gets to the 12.5-12.7 ish range it should reach

Then try connecting it to the car and measure voltage when connected. If it stays at that voltage then it can deliver some current. See if car comes back to life.

If not, measure voltage from battery positive terminal to an earthed stud on the bodywork to see if battery connection is sound

 

hi all

thanks so much for the replies battery has now been on charge since yesterday so will do as you have suggested, check the voltage and reattach to the car to see if i get any joy.

 

Hi guys

so just been out (its freezing out!!) and reconnected the battery and the car comes to life BUT there were tons of sparks putting the battery on and a strong electrical burning smell coming from the engine bay and into the cabin. Have now disconnected the battery and didnt dare try and start the car. im thinking the next port of call would be to try and test the alternator but that will require some disassembly to get at it does anyone know the best way to get at the terminals? i was wondering if removing the wheel arch liner was a good start since that looks like it would give some access?

 

sorry forgot to add reading so battery was at 13.1V prior to connecting to the car once connected to the car the voltage was down to 10.2V

 

That's frustrating. Well - sounds like something is drawing way too much current and melting down. Strange that it didn't trip out a fuse. Could be alternator. Could be one of many other items too. Think it's guesswork at this point...

Can you see anywhere that has burned / melted wires or smell around to see where it's coming from? Unless you're experienced with electrical fault tracing you may find you need a shop help you track this one down. Could be wiring harness issues, fault components, animal damage etc.

 

The fact that the smell is apparent both in the engine bay and the cabin points towards a wire issue, respectively a wire melting down because of a short cut at its end. This should not happen because there is a fuse (450A for the diesel if I'm not all wrong) between battery and generator / starter motor which would blow in case of a complete cable short cut. However if this is only a partial shortcut then the cable might get hot and cable insulations can start melting without blowing the fuse. The only thing that comes to my mind that could cause a partial short are the diodes in the generator.

Before you start messing with cables or connect the charged battery again and risking to burn your car to ashes you could test with your multimeter and remove fuses to see where the short cut is: try measuring the resistor / ohm between positive and negative battery terminal (with the battery disconnected that is). Usually that measurement will not tell much because of the car electronics interfering, but if there is a short cut you will read a value close to 0. To be sure about your reading hold the multimeters probes together, the reading should be similar to what you find in the car if a short cut is present.

If you read 0 you can start to pull fuses, I’d start with the 450A fuse for the generator / starter and see if the resitor value raises significantly. If the value is much higher after pulling the 450A fuse your next step would be to disconnect the generator. I don't know how it looks on the diesel, but from what I recall on my car you should be able to get at the generator cabling from underneath the car once the engine belly cover has been removed.

Chris

 

Remove the main cable from the alternator, insulate that terminal, then try to reconnect the battery, if you have no or very little sparks, then you have proved an alternator fault!

 

Elxcellent cheers guys I will try the tests suggested and see how I get on bit stuck in work at the mo but hoing to be able to spend tomorrow on this and make some headway. as always thanks for the advice would be lost without you guys

 

This.

 

so went ahead as you guys suggested and removed the alternator connector, all fine no issues so defo a dead alternator (backed up by when i took the old one to the shop with me to make sure I bought the correct new one the bloke in the shop turned the pulley and wiggled it and declared it to be completely FUBAR!) So I have managed to get the old one out and just have the wonderful task of putting the new one back in. all on the drive in the freezing cold :-).

Just wanted to drop a line in here and say thankyou to everyone for the help, you guys have been great and would have been very stuck without your support so nice work and if you are ever in south wales i owe you a beer!

Thanks again
Jake