My wife's mid life crisis car, and I have to admit, it's a blast. Very unfortunate it doesn't get driven much, but lately (the last year or so) there has been a very slow battery drain. I can put a full charge on the battery, and it will be completely dead in a few weeks. It's very clean, the entire mechanical part of the car almost looks new....all wiring and terminations are super clean, no oil on the engine or drive train, etc.
Have had it looked at by several local shops that claim to do Jag work and they are at a loss. Could anybody out there give me a starting point to troubleshoot this anomaly? While I am a forty year commercial electrician, automotive wiring is a little challenging.
Thank you in advance for any suggestions you may have. Last resort would be to take it to the big city Jag dealership is Sarasota where an oil change and repair of a burned out light bulb in the factory stereo was a little over a Grand $$$$$ Ouch
Again, Thank You
Randy

 

Randy,

Welcome to the forum.

I think there is a typo. "1979 XK8", I think? should be 1997 XK8.

I would put your request in the XK8 section, and the answers will flow.

 

Welcome to the forum Randy,

I've moved your question from General Tech Help to XK8/XKR forum and edited the typo in your thread title. Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Randy, make sure the little flap in the switch goes click when you take the key out. If it hangs up half way you will have a car that doesn't go to sleep. Use a little WD40 on the key and spay a small blast into the switch. Be sure to wipe off the key as not to get oil on your cloths.


Wayne

 

Hi Randy. If a Jaguar tech cannot find excess battery drain, the battery is healthy, I would recommend some type of battery tender.
As many people have pointed out on this site, alarms and the many switched, relays, etc can wipe out a battery of an idle XK8 in no time.
I purchased a solar battery tender from Harbor Freight for $ 15 which you can place on the dash or if near a window point toward day light.
You can purchase 110 volt trickle chargers if you have power near by.
I like the solar as it varies in output and time of day.
The result is my XK8 is a ready kitty anytime even if left un petted for awhile.
Hope this helps. Rich




QUOTE=RandyEllis;1343563]My wife's mid life crisis car, and I have to admit, it's a blast. Very unfortunate it doesn't get driven much, but lately (the last year or so) there has been a very slow battery drain. I can put a full charge on the battery, and it will be completely dead in a few weeks. It's very clean, the entire mechanical part of the car almost looks new....all wiring and terminations are super clean, no oil on the engine or drive train, etc.
Have had it looked at by several local shops that claim to do Jag work and they are at a loss. Could anybody out there give me a starting point to troubleshoot this anomaly? While I am a forty year commercial electrician, automotive wiring is a little challenging.
Thank you in advance for any suggestions you may have. Last resort would be to take it to the big city Jag dealership is Sarasota where an oil change and repair of a burned out light bulb in the factory stereo was a little over a Grand $$$$$ Ouch
Again, Thank You
Randy[/QUOTE]

 

The only way you will be able to trace the drain is to put an ammeter in series with the neg cable of the battery and start pulling fuses. Thats how I found the drain on my car which in my case turned out to be the amplifier for the stereo.

To do this with the car off disconnect the neg cable from the battery and using alligator clips put the ammeter in series. Set the meter range to the highest amp setting first. Its normal for the car to drain as much as an amp or more when first shut off. This should drop over an hour or so and settle in around 40-80 mils which is normal drain for an idle Jag. If its higher than that start pulling fuses until you find the one linked to the culprit and go from there. Do not try to start the car or turn the key on with the ammeter in place as this can fry the meter.



Dave

 

[QUOTE=Grant Francis;1344342]Randy,

Welcome to the forum.

I think there is a typo. "1979 XK8", I think? should be 1997 XK8.

I would put your request in the XK8 section, and the answers will flow.


Thank You Grant...yes, it is a 1997...sometimes I think in my older years I am getting dyslexia....Again, Thank You


Randy

 

There is probably nothing wrong with your car if you are not driving it for weeks or just taking very short trips.

It is normal for the car to have a slow drain. Even when the car is shut off, their is a small current drain during sleep. In addition, car batteries will self discharge slowly.

Assume a perfect 90 AH battery and a fault free car with a typical combined ignition off drain, plus self discharge rate of 50 mA/H. After 1 month about 36 AH of the 90 AH capacity is exhausted if not driven. After two months, it is 72 AH of 90 AH. In another couple of weeks it is completely dead. In reality, a used battery probably has significantly less that its rated 90 AH, so you really only get a few weeks before it is dead.

Also, when not driven much, the state of significant partial charge weakens and reduces the life of a standard lead acid battery, and the battery capacity will get shorter and shorter, every time it is recharged.

As mentioned, the solution is a battery maintainer, which is only about $50. Also, consider upgrading to an AGM type battery, which is now available widely for this car at Sears, Advance Auto, Autozone, etc. It is much more tolerant of partial discharge for cars not used regularly.

 

Just for reference my 03 sits for around three weeks on a regular basis with a 4 year old battery, starts every time with no issues. Often when I do start it it's only driven 20 miles or so. No battery drain what so ever.

Any car should be able to sit for at least over a month and most will sit for many months with no issue. If you are draining the battery in less than a couple weeks something is wrong with either your battery or a current draw on the car.

As mentioned the key flap is a know issue but there are other sources that could be the issue.

I know our cars are voltage picky but just putting a tender on it is masking the problem not fixing it.