My husband wanted to convert me from a die hard Mercedes owner to a Jag owner. He found a used well cared for Jag S style with low miles. Within the first 3 days of ownership. I replaced the Battery. I put approximately 300 miles on the car went away for 2 days; the car was left parked. I tried to start it and the battery is dead today. I have read numerous post and many theories on the battery drain problem. Does anyone know what causes this issue.

Thanks

 

It's any of quite a list and you need to figure out which one. Do yourself a favour and read the detailed and lengthy existing threads because all the information is in them. That's the fastest and most detailed way to make progress.

The forum Search is your friend and especially the Advanced part, where you can restrict matches to just this forum.

You're unlucky but cars of all makes do suffer drains on occasion.

 

Just from my personal experience: I would also check to see if the battery has any issues.

One time when I put in a new battery in my Volvo, it worked fine the first 3 or so days, and then it died on me. Took it back to Sears, and they swapped me for another battery and I had no problems afterward.

 

You should buy a hygrometer at most auto parts stores. It checks each battery cell and even "new" batteries can have a weak cell or two.

 

The first step,if you have not already done it,is to perform a parasitic battery draw test.

Basically turn all the power users in your car off,remove the ignition key,disconnect the positive cable from the battery and measure any current flowing between the battery positive terminal and the battery positive cable using a multimeter set to 10amps.(you can find details on line).

Until you perform this test you are just guessing.

If you have established that there is a parasitic battery drain,you keep following the current draw through the wiring system until you identify a defective component/wire.

If you do not have parasitic draw,load test the battery and the alternator.If both are good,then look at your use of power when operating your vehicle.

I remember a case,when I worked for our local Mazda dealer,of a customer with a new Mazda Millenia S who had apparent battery issues.After changing batteries,alternators and extensive testing we found that the customer did all short running in town and always had a full electrical load--lights,radio,ventilation etc.(Just as an aside I had the same car bought new about 6 months earlier and my original battery lasted 9years and never failed to start the car.

 

The existing threads give more information such as - critically - how long to wait if doing the above.

Plus - a lot more things to do, and sadly it really is a lot more if you're unlucky and don't stumble on the problem fairly quickly.

 

Let us also not forget, the wise BRUTAL has alerted us to a common cause of unwanted draw in the S Type... a faulty ignition switch not allowing the car to enter "sleep" mode...

 

And there's water in trunk, badly-done aftermarket electronics, faulty alternator, chafed wires, modules not going to sleep, and .... all in the existing threads

 

The faulty switch is one I've encountered. I take my key out of the ignition and everything stays on, sometimes I take it out then click the unlock button on my remote and it starts everything up. The radio often drains the battery down. I bought a battery from Battery Plus, the car drained several times, I brought the battery back they tested it and said it was still good. Unfortunately the battery kept dying. So, after a year, I threw it out, bought a larger capacity battery from Autozone and put it in. I just have to make sure that when I pull the key out the radio doesn't stay on. So far so good without having to spend $600 on a new switch.

 

I decided the drain may be related to locking the car with the remote and the alarm system.

I decided to leave the car unlocked. I had no problem for days.

A week later: I then went to the store around 11pm. I accidently locked the door with the remote and alarm. Everything was turned off in the car. The radio had not been turned on for days. I went out to the car almost an hour later with my husband. The radio was on playing loudly. The car was locked with the alarm on. I was sure I was right about the remote and lock allowing issues like the radio to drain the battery.

Then after letting the car sit for 24 hours again dead. no locking with the remote. I drove it a lot yesterday. The car was dead less than ten hours later.

The battery when jumped instantly starts. I am sure in the sleep mode no key things are being turned on. Any suggestions?

 

Any aftermarket electrical items fitted or that used to be fitted?

 

I do not believe that the vehicle has any electronic aftermarket parts.

I also realized even if the car does not have alarm set after every jump to the battery. the alarm goes off.
I also noticed while the battery was very drained to almost dead; the red light on dash signifying the alarm set was blinking, while the car was to dead to turn over and the alarm had not been set.

 

What results from following any/all of the other suggestions on this thread?