A few weeks ago I was away for 8 days, when I came home and went to start the XF, the battery was flat. I put it on charge and all was ok until last week, the car sat unused for about 6 days and the battery was again flat when I went to start the car. The battery was purchased in April this year so well within the warranty period so I took it back to the seller, a generic battery sales place. Rather than give me a new battery straight away, the guy wanted to charge it overnight and test it. He called me back this morning to say the battery tested fine after being charged. I have asked him to test it for voltage loss over the next 24 hours. If the battery is OK, I guess there must be some parasitic drain in the vehicle. I know these cars are notorious for draining the battery if left unlocked, so I always lock it.
So a couple of questions; when checking for parasitic drain with a multimeter (and I will have to buy a new multimeter, mine died recently), what should the baseline reading be, i.e. how many amps is normal?
If there is an excessive current, what are the common culprits?

 

Most car companies give 30-50ma as the limit before you need to fix anything. I have done a good bit of this work and you have several problems getting in your way right from the start??

First the car needs to go to sleep BEFORE checking for current drain. This means waiting about 30+ minutes. Now if you open a door or trunk the car is awake and you start all over. So plan to spend some hours on this. Please put a towel over the trunk latch as some cars will automatically close the trunk for security reasons if left open. This caught me on my 2014 XJR!

How do you plan to read the current drain? A regular DMM requires the meter to be in the circuit to makes any current measurements. This means you will need to unhook and reconnect wires as you go from circuit to circuit. Again this will wake the car everytime. So I recommend a low ma clamp on ammeter. These are not too common but are out there. Now you can put the meter on as many circuits as you want without disturbing the car.

I use this one as it can go as low as 1ma. Price has gone up since I purchased mine and is now around $170 depending on where you buy it. GTC CM100 meter. Note it also comes with conventional leads and can be used as a standard DMM.

There are no common culprits and you will need to go step by step until you find it. The causes are many.
It's such a big problem Jaguar released a battery care document with many details. See the attached.
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Thankyou very much for the reply and the document, exactly what I needed. Looks like In have another parameter requirement to add to my shopping list with the new multimeter, I've not owned one with a clamp-on ampmeter before,