When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My 2003 X308 is suffering from a weird parasite drain. With the car sitting in my garage the battery will drain to the point of it barely being able to start in about 4 days! All doors, bonnet, boot shut.
Obviously, first thing I did was check the battery. I installed this battery about 2 years ago. It's a Bosch G14, 95Ah, 850A. I put my battery tester on it, and it measures all parameters just fine, State of Charge, State of Health well above 85% and also the cold cranking amps are around 770A. For good measurement, I took the battery to a local battery/alternator shop I know well. They checked it with their tester and came up with almost identical results.
All the battery connections are clean, same for all ground points.
I checked the quiescent drain and found it to be about 72mA after about 40 minutes of all the various systems shutting down. Which is a bit higher than I found some years ago, about 40mA. But still, 72mA doesn’t drain this battery in a matter of days.
For good measurement, I swapped the battery, just to rule it out completely. Put the battery in from my 1998 Jeep Cherokee. Which lives outside year-round, stands idle for weeks and never fails to start immediately. (and also has a quiescent drain of about 40 mA.)
Same problem, after four days, the battery is drained to the point it will not be able to crank the engine!
So how is that possible? Are there systems that wake up occasionally? Even so, they must be putting a hell of a drain on the battery? Does anybody have any suggestions on what else to check or try?
Seems you have a much larger drain than what your measuring?
How are you measuring it? Yes 72 ma is way too high. Your car should be under 30 ma.
Attached is what Jaguar says are normal drains.
.
.
.
Guessing some lights are staying on after shutdown: put cell phone in video mode, place in glove box; put in trunk.
If that was the case it would, show up, immediately as a much higher draw than the 70 ma I am measuring now. 70 ma doesn't drain a battery in a matter of days.
Agreed but...many years ago my shop installed alarm systems into Land Rovers, they drew 45 ma and we had so many do not start complaints we quit installing in those vehicles...it made no sense, we double checked, I checked...the V dropped to 8 or so in 4~5 days time.
Please advise us when you find the answer.
With the ammeter connected in series with the battery negative terminal, start removing fuses from the fuse boxes one at a time until the parasitic draw shown on the ammeter drops. Next, review the circuits controlled by that fuse and begin disconnecting the components one by one until the the component that's causing the draw is found.
With the ammeter connected in series with the battery negative terminal, start removing fuses from the fuse boxes one at a time until the parasitic draw shown on the ammeter drops. Next, review the circuits controlled by that fuse and begin disconnecting the components one by one until the the component that's causing the draw is found.
Sorry, I don't think you understand what the problem is. My quiescent draw is around 70mA. That is still way too low to drain the battery in a matter of days. So it appears to some sort of intermediate parasite drain. With a couple of hundred fuses and not knowing when and how this intermediate parasite drain is triggered, pulling fuses is not going to tell us anything.
You can't just pull fuses on these cars. You are likely to wake up a lot of systems as you muddle along. As a bare minimum you will need to disable the various door-, boot-, bonnet switches. Please read the article I wrote on tracing parasite drains.
My problem is I don't see the parasite drain on the multimeter, but it's definitely there. Most likely certain system components power up now and then. I have been doing some reading up and it seems that is the most likely case. I need to find a way to capture what system powers on now and then. First thing might be to get myself, rent or borrow, some sort of data logger. Try and see if I can at least identify this, apparently, intermediate parasite drain.
If you have a meter with a display that will stay on, record it (e.g. using a smartphone) so you can see if (& when) there is a bigger drain than you have so far seen.
Obviously, first thing I did was check the battery. I installed this battery about 2 years ago. It's a Bosch G14, 95Ah, 850A. I put my battery tester on it, and it measures all parameters just fine, State of Charge, State of Health well above 85% and also the cold cranking amps are around 770A. For good measurement, I took the battery to a local battery/alternator shop I know well. They checked it with their tester and came up with almost identical results.
I checked the quiescent drain and found it to be about 72mA after about 40 minutes of all the various systems shutting down. Which is a bit higher than I found some years ago, about 40mA. But still, 72mA doesn’t drain this battery in a matter of days.
"If you have a multimeter you could also check the battery voltage. Without the engine running, you should have at least 11,5V, preferably you want it to be well above 12V really."
Hi Jeroen,
I took a look at the article you wrote about dealing with parascitic drains (see the sentence above quoted from your article). I would like to recalibrate your thinking when it comes to battery resting voltage for Jaguars and all other modern "12 volt" vehicles. A healthy, fully-charged battery should have a resting State of Charge of around 12.6 volts at ambient temperatures of 40 degrees Fahrenheit or higher. A battery with a resting voltage of 11.5 volts is nearly fully depleted (dead).
You mention that your battery's State of Charge and State of Health are "well above 85%," but a battery with much less than 100% of its new rated capacity may not be able to supply the current demands of your Jaguar.
Your 770 Cold Cranking Amps is low. Most batteries available in the H8 / Group 49 size that fits X308s are rated at 850 CCA (AGM) to 900-950 CCA (flooded).
Regarding your high quiescent current, the first thing that comes to mind is a leaking diode in the alternator rectifier bridge. When a diode begins to leak, its "nearly infinite" resistance to reverse current becomes instead a high resistance short to ground. This doesn't drain current as quickly as a dead short, and it doesn't cause fuses to blow, but it does drain the battery more rapidly than you might expect.
There are a few ways to test for a leaking diode. The fastest is to use a good charging system analyzer connected at the battery. Follow the analyzer's instructions and it will determine if a diode is bad (and will show the resulting excessive AC ripple in the alternator output). Some auto parts stores have analyzers with this capability.
Testing the diodes with a multimeter is more time consuming, especially with the awkward access to the X308 alternator connections. But there are plenty of videos on YouTube showing how it's done.
If you determine that a diode is leaking, it is possible that your battery has been weakened by the repeated depletions, which is strongly suggested by the low CCA.
If you have a meter with a display that will stay on, record it (e.g. using a smartphone) so you can see if (& when) there is a bigger drain than you have so far seen.
Could you measure a real parasite drain all the time? Because that is the problem with mine. The quescent drain I am measuring doesnt explain the battery draining.
Originally Posted by Don B
You mention that your battery's State of Charge and State of Health are "well above 85%," but a battery with much less than 100% of its new rated capacity may not tolerate the current demands of your Jaguar. Your 770 Cold Cranking Amps is low. Most batteries available in the H8 / Group 49 size that fits X308s are rated at 850 CCA (AGM) to 900-950 CCA (flooded).
Regarding your high quiescent current, the first thing that comes to mind is a leaking diode in the alternator rectifier bridge. When a diode begins to leak, its "nearly infinite" resistance to reverse current becomes a high resistance short to ground. This doesn't drain current as quickly as a dead short, and it doesn't cause fuses to blow, but it does drain the battery more rapidly than you might expect.
If you determine that a diode is leaking, it is possible that your battery has been weakened by the repeated depletions, which is strongly suggested by the low CCA.
thanks Don, much appreciated all the comments. My initial thought was also to double-check the battery, as I explained, I did swap it for a different one, and I still having the same problem.
I am going to test the quescent draw one more time and leave the multimeter on it for a couple of hours, see if it does settle lower eventually. If it doesn’t, the diode leaking is well worth looking into.
Another idea. Disconnect battery and attach to it a load giving 72mA. Leave overnight and see how the battery is.
If your battery is under 12V I'd replace it anyway, but 11.6V at 72mA needs about 160ohm resistor (1 Watt is enough). At 12V, 166ohm. Any 1W (or more) resistor around there will be an adequate dummy load. Maybe there are 12V LEDs that sink around that?
Are you actually locking the car? because lots of systems don't go to sleep properly until the car is properly locked - two presses on the fob so you get the second longer flash of the indicators. Without that the drains are much higher & any key/transmission near the car will wake up the security system causing higher drains.
On similar age Range Rovers there was an issue that parking near power lines could prevent the security systems going to sleep that took people on forums a few years to figure out. So it might be something really odd.
One problem I had to face when doing this kind of work and it's been mentioned above. I found it VERY difficult to keep the car asleep when making these measurements! Any small movement and the car would wake up and I would be back to waiting 45+ minutes so I could restart the test. Really got time consuming too.
So my suggestion is to NOT install the DMM in series with the battery leads. One if the car draws much amperage for any reason that's a great way to burn up your meter (Hopefully your meter is fused?). Two it's just a PIA way to do it!
I went with a clamp on ammeter so I could test for current draw without disturbing any wiring. You do need one that can measure small amounts of current and they are a bit more expensive and a bit more difficult to find. You want one that can go as low as 1 ma.
This is what I have and boy has the price increased since I purchased mine! $190!
But there are many others at hopefully lower prices!
You can also troubleshoot this using voltage drop across the fuses themselves.
You will make measurements across the back of the fuse like this picture shows.
Attached is a chart so you can tell what the amperage draw is based on what voltage you read across the fuse. This is nice because again no need to disconnect anything or disturb the car. You can rapidly go thru a fuse box with this method compared to spending hours pulling fuses!
Leave the trunk open but place a towel over the latch. Depending on your car (I have a 2014 XJR) it might have the trunk close automatically after so much time. I got bit on this a few times too! But this is car dependent.
.
.
.
Last edited by clubairth1; Dec 9, 2025 at 10:55 AM.
I went with a clamp on ammeter so I could test for current draw without disturbing any wiring. You do need one that can measure small amounts of current and they are a bit more expensive and a bit more difficult to find. You want one that can go as low as 1 ma.
This is what I have and boy has the price increased since I purchased mine! $190! Clamp On Ammeter.
.
Hi clubairth1,
Where do you connect the clamp-on milliammeter and what other provisions do you make so that you can read its screen with the trunk, hood and all doors closed so the vehicle will go to sleep? It will help others to know "The Rest of the Story."
If there's enough draw to flatten a healthy (emphasis on healthy) battery you will also have a measurable voltage drop across any fuse for the circuit(s) causing the draw. Yes, mV (millivolts) but doable and you don't need any fight with cables and clamp meter.
A fuse is a small value resistor. If it's flowing current it has a voltage drop. Most/all fuses expose little bit of metal in their top. Meter across those two.
You can test the above using any circuit you deliberately wake up.
As you remove the ignition key the ignition switch makes from pin 4 ( SLCM ) to pin 5 ( car frame ground )
Works the same and IG switch part # as the earlier X300 and maybe the 2 door sport as the X100 ( ? )
the 4 to 5 makes the SLCM command to go into a move to lock up agreements gathering and then go to sleep after X amount of time , heard of 20 - 40 milli amp in sleep mode , the trunk should be closed for the trunk lock is in the equation ( Thanks Motorcarman )
2 of the agreements are the position sensors for the seat moving back and recline and the steering column up for ease of exiting the car besides the door and trunk locks positions to lock , there is a TSB on the steering column sensor being gummed up dragging the steering column motor down to not reach full exiting position ( easy / cheap work around to not replacing the electric motor )
To remove the seat and steering from the agreements rotate the tiny round knob from auto to off , this may be the
larger knob off top of head
The ignition switch connector can be compromised by coffee spills , the car side connector half lifts straight up to bring work out to you
The pin 5 to car frame ground can get disturbed by work behind the dash
If the switch is bad no new key needed
There are some lube suggestions on the key barrel but makes a mess ( graphite spray dripping on pants leg ) common resolution
In this pic with switch removed from key barrel which is not needed
I had the same issue with my 2000 XJR, dead battery after 3-4 days. It was resolved when I replaced the SLCM which is supposed to deactivate the other modules after locking the car. I'd start investigating there using an ammeter connected in series with the battery as described above and pulling fuses. You just need to set the trunk and door locks with a screwdriver, you don't need to actually close them. It is time consuming and you have to be careful not to wake up other modules. If the SLCM is bad it will keep other modules awake so it can look like they are the problem, I replaced seat modules and door modules that seemed to have a draw before the SLCM. I'd just replace the SLCM i I saw the problem again. I don't normally believe in throwing parts at a problem but a replacement SLCM isn't expensive on ebay - I paid about $60. I posted the details before, search the archive, there's good info about this issue there. Others were finding the SLCM sits in the bottom of the trunk and is vulnerable to corrosion, mine looked fine but replacing it fixed the problem and haven't had a dead battery since.
Weird parasite drain
