I had let my 1998 XK8 sit too long without attention, consequently the battery died. I charged it overnight so I assumed everything was OK. It wasn't; as I could not get it started. Did I mess up the security system? If so, where can I get the info to set it right?
John near Baltimore

 

Quite often a totally discharged battery will not survive. Take it to a parts store and have it load tested.

 

And make the time to drive the car on a regular basis. When these cars sit for long periods of time, the factory fuel pump tends to die. That is just one common issue arising from non-use. These cars are much happier when their parts and fluids are moving on a regular basis...

 

Nice

 

OP, after you get the battery issue straightened out, get yourself a battery tender. I use the Delran Battery Tender plus . They are reliable and durable. I’ve ran over mine (not recommending) 2 or 4 times with no damage other than minor cosmetics. Try that with a plastic cased tender.

Other in this forum swear by their CTEK tender. Whatever you get, use it whenever the car will be parked overnight or longer, and the electrical gremlins will go away .

Z


PS If a person can’t drive their X-100 on a frequent regular basis, perhaps it’s best to sell it to someone who can and get a yourself a Toyota, Honda, etc.

From the fuel pumps seizing up to the electrical issues, these cars won’t tolerate sitting unused for any length of time. I directly attribute my car’s reliability to the daily driver status.

 

I now may have to add another dimension to the battery problem. I went to check on the battery itself when I was greeted by an uninvited guest. As soon as I pulled up the cover for battery, spare tire and tools, a rather healthy looking mouse scurried away. No telling how long it had been a resident. As soon as I can dispose of him I will give a look to as much of the wiring as I can easily see.

Several more attempts at starting resulted in a "sizzling" sound which I associate with a failed attempt to make an electric circuit. No sign of power to the several lights I had tried.

John
near Baltimore

 

Give him a piece of cheese and send him on his way


Check the battery cables for cleanliness, tightness and integrity - particularly the earth/ground strap. The crimps on the connectors can work loose over time

Take a look inside the high power protection module (black box in trunk on RHS behind the spare) and check the connectors are clean and nipped up.

If the battery has been left flat for a period of time it is most likely beyond redemption, as RJ notes. A failing battery can provide you with all manner of obscure, unrelated faults.

 

The battery appears brand new so I am going to charge it again overnight as the voltage only showed 7.43 volts on my very expensive Harbor Freight multimeter.
And I will be hopeful that this mouse likes cheese more than wire insulation.

John
near Baltimore

 

If the battery will not charge to 12.7- 12.8 V it's suspect. Finding a mouse is worrying, they like the taste of modern wire insulation which often contains plastics derived from soy beans.

 

When the battery sits the plates turn to lead Sulphate which then sets like concrete . The old cure was to leave it on charge for a few weeks but you are wasting your time. When charged and sat for 12hrs should be over 12.5v if not junk.
the cost of a battery New ,Delivered in the UK is half the cost of a tank of petrol ..just get a new one.

 

I guess persistence pays off. I put the charger on for one more night and this morning the battery voltage showed 12.4 volts AND the car started fine. I'll now have to sort out the several messages indicating FAIL on certain features. Thanks for everyone's help.

John
near Baltimore

 

Keep in mind that just because a battery is capable of starting an engine does not mean that it is sufficient for trouble-free usage....

 

Thats not going to last long

 

^^^^^^^^ pay attention to these comments. Aside from the starting circuit, there are miles of aging wiring and scores of corroding connections / circuit boards. This all adds up to an increased resistance to electrical current flow and the resulting voltage drop.

That is what your battery is dealing with day day out. Without keeping the battery at 100% via a battery tender you will continue to have one electrical issue after another, as the end voltage to critical components drops under a mysterious fluctuating threshold. What is sufficient to start the car is not sufficient to keep all the electrical systems from being problematic due to the inherent voltage drop.

At the outset of my XKR ownership I drove and maintained it lime any other car. I soon found myself looking at failsafe error messages and the resulting reduced performance situations, over and over. Once I took to heart the need for optimum battery health and the use of a battery tender, all the gremlins disappeared.

My battery is not new, it’s a 4.5 year old AGM battery from NAPA. But keeping it on a battery tender has ensured the reliability that was once elusive.

Z

 

The Coupe has been in the repair shop...Someone bumped it in a Parking Lot....Looks good now but when I got Home it would not start! I guess they ran the Battery down! I put my old Battery Charger on it a while ago. It's my old Schauer Charger....It sez it will go to 10 Volts...I plugged it in and it is running....BUT......after about 2 minutes it shuts off and rest for a couple minutes ten starts-up again for a few minutes.....I don't know if it is working or not.....It will only charge to 10 Volts, as it doesn't have 12 on it......It's only around 30 or 40 years old.....Should I turn it off or what?

Billy Clyde

 

Billy, unlike you, a battery charger will not last forever


time to get a new one, or at least a decent battery tender. Delran Battery tender + is my
choice, as it has a metal case allowing me run over it periodically. Other on the forum swear by their CTEK tenders.

either one will resurrect a dead battery better than what you are now using.

Z

 

+1 Z.
My Mar 2015 Advance Auto AGM battery works as well as new.(if not better... I suspect some sort of internal battery memory goings-on similar to that of NiCad's) I attribute this 7+ year success to constantly using a 4A Deltran AGM battery tender. (Mine has a plastic housing so I am extra careful not to drive over it!)

 

You need to be careful not to rely too much on the battery tender...you only need a fraction of an Amp Hour to work the starter and after that the alternator does all the work.
Any battery over 4 years old I am suspicious of . AGM is not magic technology it just refers to the glass fibre used to separate the plates. The only advance in tech was some years ago when Antimony was removed ..caused high self-discharge.
You need to periodically test the battery with one of these electronic testers ..gives the AH capacity etc in its display
Quite cheap and is the modern replacement of the old load /toast rack tester .

 

In theory the alternator does do the major lifting after the car has started. But with our car’s delicate electrical needs, the perfect alternators output doesn’t charge the battery to level needed.

In my experience, the alternator won’t improve the charge that the battery starts out with, it only maintains it. That is not unique just to our aging Jaguars.

If the battery is not 100% to start out with via a battery tender of choice, one may have a perfectly good alternator but our cars (specifically)will continue to have electrical gremlins out the wazoo.

Once the practice of using a battery tender has been instituted, the gremlins disappear..

The numerous anecdotal posts on this forum support the theory that the battery tender regimen has shown substantial effectiveness in eliminating impossible to trace electrical issues, ie gremlins, even when the charging system is putting out the factory specification of voltage amd amperage.


Z

 

Totally agree ...we are all riding around with batteries 80% charged relative to max capacity because we only charge them to the low 14s . The days of gassing batteries at 15.3v are gone .
If you worked on canal boats ( live aboards) they are fanatical about charging to full capacity and modifying the alternators to match