You were right first time on pressing the brake pedal harder.

Thank you again - fabulously helpful posts.

Much appreciated.

 

Hey just glad it was that simple!
Every once in a while we all deserve a bit of luck!

Enjoy your new to you XJ!
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Thank you so much. Your judgment was accurate !

As for enjoying it, I've spent nearly $100 in gas since I picked her up. Shall I watch CNN or Fox or phone a friend or go to Starbucks? Nah - instead, next minute I am down shifting into another tight left hander, and realizing that when I come out of the bend and get held up on the straight you need to have engaged S mode otherwise it upshifts to D, and that can be a wee bit embarrasing. I'm hooked... I'm going to have to sell it and buy a Volvo 240D.

 

Frankly the XJ X351 series are power ******! There’s no other way to put it. I’m on my second late model XJ and compared to all the other Jag's I’ve owned in the last 30 years; This one sucks the most. I’m talking about power—as in usage!

I had an XF (X250) during a hurricane, and even though it was filthy, it survived and didn’t get any ocean surge (Saltwater and Jaguar electronics do not mix! KABOOM!!) Since we had no power as well as AC in the house; at night when I couldn’t sleep, I’d go sit in the XF & roll down all the windows, and open the sunroof and play the radio nearly all night!

The XJ (X351) radii shuts down in less than a half hour. That’s why a few years after they were introduced, they added an extra battery and with the late model ones; The sales people were told to really push a battery tender with every purchase.

So as the gentleman that talked about using a voltmeter to test the battery draw, it is important to know that if the battery drops down into the upper 10V or lower 11’s it’s practically a paperweight by then. A dead battery is not 0 V. It’s just a few volts less than the over 12 we’re supposed to have. Now here’s the fun part; every time you try and start the car unsuccessfully, it draws down on the battery more.

I learned that the hard way after an oil change and having to turn on the car to check the oil level since we have no dipstick. And then a short run a few blocks to drain the oil and then another short trip to buy an extra quart to keep in the trunk Aaaaannnd NO START! The so-called experts in the auto parts store kept saying solenoid solenoid and I actually tried hooking up a scanner too, and that even drew power—added to the fact that I kept trying to start it repeatedly that kept drawing more power. Then they want to offer their little jump boxes which they claim are 3000 mV!!!! (which is like 3V.) JLR recommends a jumpstart USING CABLES (And you don’t want a smart car for the power supply; something with as big engine as yours or better). And leaving the cable hooked up for at least five minutes, because our batteries draw a lot of power and those little boxes have a tiny little battery inside which can generate high voltage, but only for maybe a fraction of a second!

So I walked away, came back several hours later and it started right up. All the start attempts and everything else wasn’t giving the battery a chance to regenerate itself.

Here’s the key fob issue; When you approach your Jaguar you may notice things start to light up before you even climb in. (This is a Especially noticeable at night.) Your car to be ever so helpful is more or less pre-starting so if you sit in your car, even waiting a bit between attempts it’s still drawing down battery power even without starting. (Which is why leaving and coming back hours later, was the best thing I could’ve done!)

And that’s also why someone spoke of having to replace or keep a battery so often just being close to your car, it can be transmitting signals to it, which draws down your fob battery. I now use a faraday cage made simply from an empty Altoids mint tin! (I learned this when I had my XF previously and I thought it was genius to park right next to my bedroom window, so I would always be able to keep an ion it, not realizing that the keyfob was talking to the car and going through a pre-start sequence that I wasn’t aware of draining the fob battery as well as the car battery prematurely.

Somebody should figure out a way to mod the car. I have two size batteries maybe even a second alternator!

 

The way you do that is pretty straightforward. You put an Amp meter on the battery and start pulling fuses until you find out which accessory is using all the power. It could be something broken.

My previous XF's started eating up the battery very quickly, if the car was left unlocked. Our Mercedes SUV has started doing the same. We just leave them locked, and it hasn't been a problem. If I need to do any work that requires keeping the power on to the car for extended periods, I hook up a car charger.

 

MC690, what you talk about is pretty straight forward. Done this mod to a lot of trucks. You would need to add what is called a battery isolator. In short, it is a smart device that does a few functions: 1) separates 2 (or more) batteries from each other so when one battery gets drained, it doesn't drain all of them), 2) it controls the charging rate to each battery, giving the primary battery all the power it needs and then any additional power, it sends to the rest of the batteries, and 3) can keep your starting battery fully charged while you use the electronics of the car so when you need to go home, you have a fully charged battery to start the car with.

Simplifying the actions needed to install this, it is nothing more than taking the positive battery cable, attaching it to the common input to the battery isolator and then on the output, putting your starting battery on the "1" terminal and your accessory battery on the "2" terminal. You can kill the "2" battery and if the electronics of the car (what is needed to start the car) are attached to the "1" battery, the car will start right up.

NOw, be aware that there are devices out there that they call "battery isolators" that are nothing more than high current relays. that is not what you want. A true battery isolator is going to look somewhat like a car amp and have 3 (possibly more). terminals coming out the top of it for connecting your batteries.

I wonder what our cars would do with the new lithium ion batteries. They are still 12V, but have like 600 amp-hours of life compared to the 80-100 the AGMs have. That would solve a lot of issues too. The big thing I see is if the computer is counting the amps with the battery monitor, it may shut off the car after it sees say 20 amp-hours leave the battery. For an AGM, that would be enough to question a start. For a lithium battery, that would not even affect it.

 

The second battery was for the start/stop system only. No other function.
Glad mine stopped working!
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