Battery being drained. Need help

Discussion in '308/328' started by Grim Reaper tr, Sep 8, 2020.

  1. Grim Reaper tr

    Grim Reaper tr Karting

    Oct 6, 2014
    Hi all,

    Thought I would ask the collective brains trust here for help.

    308 QV GTS Euro fitted with a Cobra car alarm. Alarm not turned on via remote.

    It completely drained one battery standing. I thought it was the battery so replaced it with a new one, larger and with more CCA's.

    Its totally drained that one as well! Alarm not turned on.

    Any ideas/suggestions? Where to look?

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  3. Brian Harper

    Brian Harper F1 Rookie

    Feb 17, 2006
    San Jose area
    Full Name:
    Brian Harper
    You mention the alarm a couple of times and I suspect you suspect it. And I suspect with good reason. Disconnect the alarm power lead or remove the fuse, it probably has a plastic inline capsule with a fuse in it. "Not set" isn't the same as completely off. See how your battery holds up.

    Do you have a voltmeter/DVM?
  4. Grim Reaper tr

    Grim Reaper tr Karting

    Oct 6, 2014
    Hi Brian,

    Thank you for the suggestion.

    Believe it or not I have only set the alarm once in all the time I have owned the car and that was to test it as there was No instructions.

    There is a blinking red light which I have to turn off with the remote button before I can start the car.

    So I gather that's an immobiliser? A seperate push on the remote activates and arms the car alarm.

    Weird thing is that I've never had this problem and car sits most of the year connected to a trickle charger.

    I will borrow a voltmeter shortly.

  5. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    Full Name:
    Mike 996
    Aftermarket car alarms are notorious for causing rapid battery draining. Frankly, I would remove it completely. The risk of someone stealing an old 3x8 is probably around the same as the risk of you being eaten by a great white shark...while sitting in your living room!

    OK, OK...not that quite that low! :) But in reality, car thieves are not interested in exotic cars; there is no money to be made in boosting them.
    JohnnyTS likes this.
  6. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Rossa Subscribed Owner

    May 4, 2001
    Birmingham, AL
    Full Name:
    Being a three pedal, the chances are near zero this day and age someone could drive it away
    DonB, JohnnyTS and Brian Harper like this.
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  8. kcabpilot

    kcabpilot Formula 3

    Apr 17, 2014
    California SF area
    Full Name:
    The car has two separate busses, the hot buss and the switched buss. The hot bus is connected to things like your interior and exterior lights, the clock, the cigarette lighter and the switched buss goes through the ignition switch to fuel pump, ignition, fans, radio, etc. There is also what I'd call a freelance buss which are things other people hooked up like alarms, radar detectors, USB ports and audio equipment. No way of knowing how those are wired without digging into it.

    Without a meter you can do nothing other than take shots in the dark. With a meter find the hot bus, disconnect the feed and put your meter in line as an ammeter then remove one fuse at a time until the current drops to zero and that will be the circuit you're looking for.

    Good luck.
    JohnnyTS and thorn like this.
  9. Grim Reaper tr

    Grim Reaper tr Karting

    Oct 6, 2014
    Thanks to everyone for their help and advice!

    Will report back with what I find.

  10. jon s

    jon s Formula Junior

    Mar 9, 2005
    pocasset ma
    Full Name:
    jon shoukimas MD
  11. jon s

    jon s Formula Junior

    Mar 9, 2005
    pocasset ma
    Full Name:
    jon shoukimas MD
    disconnect pwr lead to clock k huge drain like 10 amps as i recall worked for me when car was stored for weeks good luck jon s
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  13. mike32

    mike32 F1 Rookie

    May 13, 2016
    With it sat on a trickle charger you would have no problem as the charger is supplying the drain you now have. If you still have a problem after pulling the alarm fuse, then fit the ammeter in line with the battery, key switch off. See if any amp flow and pull fuses until it drops off.
    thorn likes this.
  14. JohnnyTS

    JohnnyTS Formula Junior

    Jun 3, 2012
    just outside JHB, RSA
    Full Name:
    the analogue clock will pull about 20mA and should not drain the battery within a week or two,

    I always pull the battery disconnect switch after a drive, my 328 will last about two weeks if I don't pull the switch and my standard battery is now around 2 years old, the previous one lasted 7 years but I did not always pull the switch on it.

    If I don't get chance to drive my car within a week or so I will connect my battery maintainer for 5 to 8 hours until it shows full.

    your problem is something else, does the alarm have a immobilizer ?

    take kcabpilot advise and try and determined where the drain in coming like he explains...
  15. mike32

    mike32 F1 Rookie

    May 13, 2016
    If you are not sure if you have both an alarm and immobiliser, look under the carpet where the passenger feet go. If its the same as the mondial there will be a metal plate and it might be mounted on the back of this plate.
  16. DonB

    DonB Formula Junior
    Rossa Subscribed

    Nov 11, 2003
    Full Name:
    Don Bartz
    Let's see. There's the Hot battery Buss, Left and Right AC Busses, and off the Left AC Buss is the Ground Aux Buss which feeds the STBY Emer. AC Buss and Captains instruments.....oh wait, I think this is for 727. Sorry.
  17. thorn

    thorn F1 Rookie
    Silver Subscribed

    Aug 7, 2012
    Tallahassee, FL
    Completely agree. My car will start after a month.

    If anyone's clock is pulling 10 amps, you've got a major short going on. And probably a fire hazard.
    mike996 likes this.
  18. steved033

    steved033 F1 Rookie
    Silver Subscribed Owner

    Apr 12, 2017
    Atlanta, GA
    Full Name:
    Steve D.
    Connect a multimeter set to amps on the negative side of the battery (in series). Pull fuses until the amps drop. Voila!

    Scott (ratarossa) had a great vid on his 456 about this.

  19. ginoBBi512

    ginoBBi512 Formula Junior
    Silver Subscribed

    Oct 9, 2016
    I have a battery tender on my 328, this may be a solution to having to unplug anything. My car has an analog clock, and it was draining my battery, now my car is hooked up to it when parked , and I have no issues with a dead battery

    Thank you

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