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Thread: Flat Battery

  1. #1
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    Flat Battery

    Aaagh! Finished fitting my Jagwrangler roof & rear window operating kit last Sunday (just over a week ago) & carefully put everything back together. (I may post separately about that later.) Drove the car on several days following, operating the roof many times, both remotely and directly, and operating the rear windows. Always behaved beautifully, as did the car generally. Well pleased, so filled up with fuel, locked the car fully & put the cover back over it. Didn't bother to re-connect the CTEK as I was planning to use the car again within a week.

    Went to retrieve some items from the boot this morning, pressed the remote key to unlock the car, and - nothing. Long story short: battery voltage down to just over 2 volts. No wonder the car didn't even unlock! Had to use the mechanical lock behind the rear number plate (which, some time ago, I fitted using Velcro - me cynical pessimist!)

    Nothing obviously amiss - I looked at the battery and its connections and all seem fine. Battery is a good-quality Exide and just a few month old, and much of the time left connected to my CTEK. All I have done now, so far, is re-connect the CTEK and hope the battery hasn't suffered too much permanent damage from its severe discharge. We will see if it re-charges satisfactorily and holds ts charge.

    Big question: what caused this? Good battery, car fully locked and only left a few days. No idea if this problem is anything to do with fitting the Jagwrangler roof kit - may just be a coincidence - and anyway any substantial electrical fault / short-circuit / incorrect connection anywhere would surely blow a fuse?

    Any suggestions what I should check first? If I want to disconnect the roof and/or rear window circuits to eliminate them from my enquiries, which fuse(s) should I pull, please?
    Jaguar 2007 4.2 litre XK (X150) convertible
    Maxzda 2007 MX-5 2.0 litre (non - 'Sport') roadster-coupe
    Skoda 2007 Octavia 2.0TDI 4WD (not a Scout) estate
    Reliant 1975 Scimitar GTE SE5a (off the road after 243,000 from new)

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    If you had the doors or boot open for long periods during the installation this can run down the battery very quickly, especially if you only had a partial charge to begin with.. That seems like it could be the likely culprit. The remote module goes into sleep mode, so it should not be draining the battery.

    Keep in mind that the CTEK will take around 3 days to recharge a fully discharged battery.

    Also, after a drive of a few minutes, I suggest checking to see if whether either of the battery cables is hot. The crimps on these cables (especially the negative cable) often go high resistance and this can prevent proper charging of the battery while driving.
    www.thejagwrangler.com
    2001 XKR
    White Onyx convertible, S-type 4.2 Quartz sedan., 2007 XK Ebony Convertible

  3. #3
    Senior Member simpo3's Avatar
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    Quote Originally Posted by Titus View Post
    Aaagh! Finished fitting my Jagwrangler roof & rear window operating kit last Sunday (just over a week ago) & carefully put everything back together. (I may post separately about that later.) Drove the car on several days following, operating the roof many times, both remotely and directly, and operating the rear windows. Always behaved beautifully, as did the car generally. Well pleased, so filled up with fuel, locked the car fully & put the cover back over it. Didn't bother to re-connect the CTEK...
    I'd guess either all that roof up/downing has taken out more than you thought, or the new gadget you fitted is using power somehow. You could find out which by recharging the battery but leaving the roof alone - does the battery still go flat?

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    Quote Originally Posted by simpo3 View Post
    I'd guess either all that roof up/downing has taken out more than you thought, or the new gadget you fitted is using power somehow. You could find out which by recharging the battery but leaving the roof alone - does the battery still go flat?
    (1) No, after I had finished playing with the roof I then drove around quite a bit. The car regularly re-started each time and was fine when I parked and locked it. The battery has gone flat (not just a-bit-too-flat-to-start-the-car, but completely, utterly flat-down-to-just-2-to-3-Volts-flat since I parked and locked the car.

    (2) Yes, I am carefully and fully re-charging the battery right now and of course will see if it goes flat again without me operating the roof.

    The problem might be nothing to do with the roof whatsoever.
    Jaguar 2007 4.2 litre XK (X150) convertible
    Maxzda 2007 MX-5 2.0 litre (non - 'Sport') roadster-coupe
    Skoda 2007 Octavia 2.0TDI 4WD (not a Scout) estate
    Reliant 1975 Scimitar GTE SE5a (off the road after 243,000 from new)

  5. #5
    Senior Member simpo3's Avatar
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    Hmm. I had an S-Type which did this at random intervals, sometimes every few weeks, once twice in two days. The battery would go from normal to utterly flat overnight. No point in taking it to a garage of course because it wouldn't do it to order. Then one evening after I'd locked the car, I went back outside for something and saw the clock display glowing brightly. Unlocking and locking the car made it go out. So I reckon that was it. And so maybe something in your car is doing the same. As to what the something is, I refer to you people cleverer than I!

  6. #6
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    Thanks, simpo3. In a perverse kind of way, that's almost reassuring (= 'I am not alone'!)

    Did such utter battery flattening / draining shag the battery?
    Jaguar 2007 4.2 litre XK (X150) convertible
    Maxzda 2007 MX-5 2.0 litre (non - 'Sport') roadster-coupe
    Skoda 2007 Octavia 2.0TDI 4WD (not a Scout) estate
    Reliant 1975 Scimitar GTE SE5a (off the road after 243,000 from new)

  7. #7
    Senior Member simpo3's Avatar
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    No. After 24 hours on a charger it was fine again.

    At first, when I had something important to drive to the next day, I'd leave the car in the road so if it was dead I could take the TVR. Eventually I bought a spare battery and kept it ready in the garage. I got quite adept at swapping them over! Then it only beat me once - when it killed battery 2 before battery 1 was recharged.

    Once I'd learned to check the clock display after locking it, it never happened again.

  8. #8
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    Quote Originally Posted by simpo3 View Post
    Once I'd learned to check the clock display after locking it, it never happened again.
    Right! Thank you. So if I've got this correct, what you're saying is, make sure the car has really shut down after you think you've locked it?
    Jaguar 2007 4.2 litre XK (X150) convertible
    Maxzda 2007 MX-5 2.0 litre (non - 'Sport') roadster-coupe
    Skoda 2007 Octavia 2.0TDI 4WD (not a Scout) estate
    Reliant 1975 Scimitar GTE SE5a (off the road after 243,000 from new)

  9. #9
    Senior Member simpo3's Avatar
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    Quote Originally Posted by Titus View Post
    Right! Thank you. So if I've got this correct, what you're saying is, make sure the car has really shut down after you think you've locked it?
    It seems that would be a start. In mine the fault was obvious when you knew where to look, but the fault in yours could be anywhere so I don't know how you could tell.

    I know that Jags continue to use power if they're not locked, but I didn't think that was enough to kill a battery overnight. In my case there was definitely a gremlin as the clock display glowed brighter than normal.

  10. #10
    Senior Member No Quarter's Avatar
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    Hhmm, at the risk of sounding like, hey, I don't have this problem, I don't. I can leave it for weeks and not lock it and open doors occasionally. I have the Jag Wrangler thing, and while I seem to remember a diode flashing all the time, apparently it doesn't use much. I still have plenty of power to start it. Once or twice after winter the cruise control didn't work on the first drive...

    These cars are pretty fault-free, but the electrics.... Worrying.
    2007 Jaguar XKR Convertible
    1978 DeTomaso Longchamp
    2009 Cadillac CTS-V 650HP
    Author of Tuning Made Easy:
    http://www.amazon.com/Tuning-M...l-Hass/dp/8771144625

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