I am an idiot. I have read the various posts but am now afraid of causing more harm than good. I had a bad battery and got stuck in a parking lot so I got a battery starter from NTB, jump started the car and drove it home. I then removed the battery and took it to NTB to analyze. It would not hold a charge so I purchased a new one and came home. I went to install the battery and my trunk was closed so I inserted the key in the trunk and guess what I only have the green headed Valet key. So now I don't have a battery in the trunk so I don't think the solution of connecting a battery to the B+ post next to the fuse panel in the engine compartment will work since there is no battery in the car. I will be providing current to a battery cable. I tried the screwdriver thru the hole behind the license plate but there doesn't seem to be anything there to unlatch? It seems like my only solution is to buy a new key from Jaguar and open the trunk. The moral of the story is don't be so eager to DIY. I should have driven the car to NTB they would have checked and installed a new battery and I would be happily motoring along. If anyone has a solution I would be most appreciative. Will see if anyone responds before I buy a new key.

 

I forget to mention it is a 99 XK8

 

The battery to the B+ under the hood at the fusebox should work, even without the trunk battery. Connect the minus to the chassis at one of the strut bolts. You should be able to do this with a jumper cable.

The only hazard I see is if your battery + cable in the trunk is touching the chassis by chance.

 

I concur with WhiteXKR. I also think that it's unlikely for the battery cable in the trunk to be touching anything that would ground it out. The chassis is painted, and that should insulate it enough to allow you to open the trunk, even it the cable is touching the chassis.

 

My sincere thanks to both of you on your responses to my issue. Rather than risk any damage (I have already done enough) I conceded and went to my Jag dlr and purchased a key $79 incl. tax and used it to open my trunk. Battery now installed and things seem to be O.K.. Will have to get the key programmed if I want to use it for starting the car, another $120. I am surprised that there was not an error message or code to indicate that the battery would no longer hold a charge. I would encourage others to check their battery annually if it is over 5 yrs old. It may save a lot of time and money to replace it if it is weak.
Happy Motoring!

 

Good for you. I'[m glad you have it sorted out. BTW, those are better than normal prices for the key and programming, just FYI.

 

What many people do not realize, is that altenators do not fully charge batteries. They will normally only charge up to 80% of a batteries full charge and over time, not even that much. But to answer your question, you would need a battery tester to test your battery and iwould have to be configured to stop power to the car and test the battery, which is not feasible and of limited use. There is no real way for your electrical system to know when the battery is just weak and when it is actually dying.

Though I do know that there are some cars with this kind of technology built in, but I do not see how beneficial it would be in the real world, as leaving lights on, door ajar and other things are the most common reason for batteries dying.

You could get a battery charger, the high end ones usually can test for weak batteries. I like trickle chargers and as always, never charge a battery with it connected to the car, you could harm tyour cars electronics.

Sorry for going off on a couple different tangents.............

 

When, after purchasing the vehical, did you realise that you only had the Valet key?

Bob

 

It has been about 5 yrs. since I purchased the car.