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996 Battery Drain

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rodneyhynejones PCGB Member
2020/01/14 12:44:52 (permalink)

996 Battery Drain

I have a 2002 (July) C4S and recently noticed that, if the car is left locked with alarm on for more than about 5/6 days, the battery will hardly turn over the starter motor.
In addition after running the car for 30 mins or so, if I have to stop for a few minutes, it is likely it will hardly turn over again and I have had to push start or jump start it. If it is left for a longer period, say an hour or so, it is not so much of a problem. On one occasion the alarm even went off and I had some difficulty turning it off.
I read somewhere that one problem could be that, although when locking the car the courtesy lights go out, they may still be a source of draining.
Has anyone had similar problems? 

7 Replies Related Threads

    PCGB Member
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    JOHNNYBOY552 PCGB Member
    Re: 996 Battery Drain 2020/01/14 13:07:03 (permalink)
    I have 2003 C4S and use the ctek trickle charger through the cigarette lighter. Solves the problem of the flat battery after a few days. Not so sure on the other problem. The ctek will also condition the battery. They are about £80 on amazon. Hope you get it sorted
    PCGB Member
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    Motorhead PCGB Member
    Re: 996 Battery Drain 2020/01/14 13:27:27 (permalink)
    The first thing I'd do is to get the battery checked-out properly - that could well be the primary source of your problems. Any of the battery suppliers will be able to this for you, probably FOC, and the test will indicate if there are any dodgy cells.
    If the battery proves to be OK then maybe there's a bad earth contact on the battery or starter motor?
    You can use a camera or phone to record in the bonnet or glove compartment to check that the courtesy lights are going out when you shut the lids.

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    David Beatson
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    David Beatson PCGB Member
    Re: 996 Battery Drain 2020/01/14 13:33:13 (permalink)
    As mentioned by others, check the battery condition and the alternator.  I normally have mine on a cytek charger but not for the past 3 weeks and it starts fine. if you have a tracker this can drain the battery. Also check any interior lights to see if they are still on when all doors and bonnet/engine lid are closed. 

    911 996 Carrera 4
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    Richard_Hamilton PCGB Member
    Re: 996 Battery Drain 2020/01/14 13:33:35 (permalink)
    There will always be a small battery drain, but it should be fine to leave it for 5 days.  It drains less when locked than unlocked, as the alarm module goes in to energy saving mode after 5 days.

    As Jeff said, the first thing to do is get the battery and earth straps checked.  If they are OK, then there is another parasitic drain, and there is only one way to check it properly.  See the attached PDF.

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    C2dweller PCGB Member
    Re: 996 Battery Drain 2020/01/14 15:03:40 (permalink)
    The hot start issue is most likely a starter motor problem.  We replace a lot.  There aren’t many other ways to diagnose the fault. I don’t believe it’s related to the current drain, but this would be simple to check when the starter motor is being replaced.
    KR Lee

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    rodneyhynejones PCGB Member
    Re: 996 Battery Drain 2020/01/14 15:07:49 (permalink)
    Thanks guys. Some things to work on
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    rodneyhynejones PCGB Member
    Re: 996 Battery Drain 2020/01/14 15:22:32 (permalink)
    I'm beginning to think you're right. On a couple of occasions there has been a slight 'groan', for want of a better word, from the starter motor after it started
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