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,

 

But heed the advice. Disconnect the battery at home, charge it fully before bed. Disconnect the charger. In the morning take a reading. It should read 12.6v. If its 12.4v or less, its done.

 

I thought this was the norm for my 2010 XF.
I added a trickle charger and plug it in on a timer any time I’m gone for more than 5 days.
Being parked outside, in Michigan winters I use the trickle charger every day.

 

Unfortunately I think your right! Current drains are beyond common and again I don't know why. As posted in many places even Jaguar keeps all the cars in their show rooms on a CTEK charger! So a lot of guys just use the trickle charger and don't worry about bit.

But if things are working no need for the charger. I have left my 2014 XJR for 6+ weeks at the airport with no problems starting the car. My factory battery also lasted 10+ years! A record for me. Jaguar made many electrical changes in the 2013-2014 years and I think it helped a lot.

If you do find your drain post back as we all love to hear a successful repair!
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Waiting for a new multimeter to arrive, first step will then be to measure the current at the battery. I'll report back.

 

Many fuses have tiny metal bits on their top (each side of the actual fuse) where you can put a meter on mV to see the voltage drop across the fuse. A fuse is a very low value resistor so if current is flowing there's a tiny voltage across the fuse (thus mV). The ones that are zero voltage drop are not causing the problem. The others are suspect circuits.

 

I got a new multimeter a couple of weeks ago but have only just had a look at the car with it to check for excessive parasitic current. With the car locked, the boot open but the boot catch latched so the car is 'closed' electrically, I disconnected the battery negative terminal and put the meter in line between the negative cable and the battery neg terminal, initially had about 200mA reading until the car went to 'sleep' at which point the current dropped to 24milliamps- exactly what the document from Jaguar says is the allowable reading. So it appears I do not have a parasitic drain problem. I figure that a current of 24mA will drain approximately 3 amp-hours from the battery per week, perhaps that is simply enough to leave the battery flat after 8-10 days of sitting locked and unused. I would never have considered that parking a car for a period of just over a week necessitated special consideration.
I'm considering perhaps installing a small solar panel on the garage roof to plug the vehicle in via an anderson plug to the battery and trickle charge; I do this with my tractor and a couple of other machines that might go unused for weeks or months, seems like this should not be necessary for the car but...
Does anyone know if the electrical system will tolerate a trickle charger being plugged direct to the battery in this way?

 

That sounds OK and you can park for a lot longer than a week (so long as the battery isn't largely dead anyway).

 

I had a further thought on this; there is wiring in place for the trickle charger that is used to maintain the battery when the cars are shipped from the factory- wondering if this can be utilised to connect a solar panel input?

 

I'll second this. Use a Battery Tender or equivalent and all your problems go away.

 

My understanding is that no trickle charger is used but rather a relay or the like which cuts power completely.

 

I think JagV8 is right? It's called a transit relay and it cuts all power from the car while it's being shipped.
Then it's removed by the dealer. In theory anyway!

Jaguar has a charging kit out so I think they want you to wire a maintainer in separate from the transit relay wiring?
Attached are the instructions but I have not seen anyone use this as it's pretty simple to hook up a maintainer anyway?
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