Battery discharging problem

[pbartlett]

2000 XK8 75k purchased March 05, history largely unknown.

Something is draining the battery when the car is not being used. If left unused for two weeks the battery is too flat to start.
Discharge pattern is very repeatable since I have monitored the voltage over time. Something is drawing current for 20-30 mins and then nothing for ~10-12 hours, This pattern is repeated until the battery is flat.

I have sequentially pulled all the fuses (all five boxes in turn) with no effect. Problem still occurs!

I now suspect a hidden "tracker" anti-theft type device has been wired in somewhere. Anyone know where I should start looking - OR - any other ideas.

Has anyone else seen anything like this?

All suggestions gratefully received.

[SWF]

An intermittent boot light ?

[Sharfrs2]

I've heard of people having similar problems, with an undesirable tracker being fitted. The trouble is the tracker company don't like telling where the unit is fitted, (obvious really). But this doesn't help if you don't have the tracker number and don't subscribe. Start hunting for something that doesn't look right I guess. Sorry to be so vague, but it is an difficult one.

Might be worth checking other, easier oprtions first, as mentioned by SWF.

Dave

[pbartlett]

Thanks guys.

I've checked out the boot light by pulling fuses. No problem.

I still suspect some form of Tracker but don't know where to start looking.

The solution for now is a battery charger. Less than ideal!

Phil

[WULLIE4567]

Hi Phil
I was looking over the postings today to see if anybody was having problems with battery discarge when the car is lying for a week or so.
I have had my 2000 W reg,XK8 coupe for six monthes now and have the same problem. I havent really looked for anything yet but I suspect the batterys on the way out? It's fine when used daily or two three time a week.
Did you find out what was causing the problem with your car.

Cheers

Wullie.

[pbartlett]

Hi Wullie,

When I first had this problem I thought - need a new battery - so I bought one. It made no difference.

I still have the problem. I just put the battery on charge if I leave it for more than a week without using it.

A friendly mechanic has suggested that the battery I bought was a dud. The only way to check this out is to buy yet another one, but I am reluctant to do so without being sure this is the problem. (But I have now had this one (and the problem) since March 2005, so it might be time to consider another battery).

It sounds like your battery is only lasting a few days though. Perhaps yours is on the way out.

If you decide to get another, let me whether or not the problem goes away.

Good luck,

Phil

[WULLIE4567]

Hi Phil
I will let you know the outcome, should get worse now temp's are down to between 6 and 0 degree's sometimes. (stay in ayrshire).
Is there anybody else had or having this problem out there if so let us know how you cured it???
I have even shut the wife in the boot for for a short while to check the boot lights were staying off, huh' she wanted back out, shame.

Cheers Phil, the XK8's are still a dream car to have and drive, and these wee problems don't put me off owning one in the least.

wullie.

[designxkr50]

The problem with tracker systems is that they are hidden in the most obscure places, obviously as if they were easy to locate there would be no point in having one. We have found them in various places when stripping cars.

If you disconnect the power distribution cables in turn (large cables that go to the fuse boxes, 1 on each side of the dash, 2 in the bonnet and one in the boot) you should be able to work out where the connection has been made to. You could then look for any odd looking wiring that has been added to that point.

If you want some help with what to do, give us a call on 01264 333523 during office hours or 0770 4321556 (mobile) and we can give you an idea of what to look at.

Kevin

[WULLIE4567]

Hi Kevin
Thank for the info I will have a look at this.

cheers
Wullie.

[dredr62]

A complete shot in the dark as I am far from technically minded but - a couple of years ago I had a 2002 S Type V8. The battery would discharge quickly if not used daily. Turned out that the mirror light in the sun visor was not shutting off when the mirror flap was closed and the visor pushed up. Only noticed this by chance when I pulled the visor down and noticed it was very hot to touch. Just a thought since the visor set up is practically the same in the XK!

[mike020150]

I think I may have mentioned this solution before on the Forum, if not here goes. Jaguar did have a puzzling battery discharge problem at one time on several models. The engineers tracked it down to drivers leaving either the auto wipers or headlights (I can't recall which) in the on position after turning off the ignition. This allowed the relevent auto sensor and its related computer to remain live and to keep checking periodically for example for rain drops. The cure was a simple change to the loom to ensure that ignition off would kill all the circuits. If nothing else helps and you have these gadgets, try turning them off before stopping the engine and see if it makes a difference. Mike.

[WULLIE4567]

Cheers Guy's
Checked interior mirror lights ok, wiper and head lamp switches are alway returned to off position. So I will keep looking, it is not getting any worse in the cold weather yet.

thanks for the info

Wullie.

[MyQuest]

Wullie, this may be worth checking as I had a similar problem 18 months back, which drove me to distraction for ages.

The power occasionally went down to 9 volts and I checked every wire/connection/fuse box etc. possible but could not find the resistance. (The battery showed full charge at the terminals). Even did it to me in the middle of Barcelona!!

I got to the point of having a voltmeter in the battery compartment ready to check it when ‘playtime’ started.
Finally realised that whilst removing the boot floor/cover to retrieve a screw, the lights went from dim to normal – ‘aha’ says I.

The main positive connection from the battery to the two 250 amp fuses appeared sound (fuse block end) but when pulled, voltage varied. I removed the cable, cleaned, whacked(!) and SOLDERED the large spade end terminal – been fine ever since.

Michael

[WULLIE4567]

Hi Michael

I will check this out tomorrow, worth checking all the wee tips from fellow members. I have noticed my interior lights do flicker a bit don't know if this is the norm.

Thanks for info

Wullie