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My battery makes a "thunking" sound

Discussion in 'Model S: Battery & Charging' started by Runs Kwh, Dec 14, 2014.

  1. Runs Kwh

    Runs Kwh Member

    May 16, 2014
    Los Angeles
    We've had the S for just shy of 6 months and have about 10K miles on it. I've noticed that when charging or sometimes waiting at a light or when the car is stopped that there's a "thunking" sound that is coming from somewhere in the car (seems to be from the back). It sounds like a "thunk" or like if you have a hard ball that is rolling around on carpet (if that makes sense).

    Is this a normal sound, it seems to be - perhaps - tied to the battery. BTW, we don't have anything rolling around in the car - and it happens when the car is completely motionless when charging.
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

    Mar 8, 2012
    The Model S has any number of things that might make noise when stopped/charging/running. Solenoids, relays, cooling system pumps, brake pumps, etc. Some of these systems will activate occasionally even when the car is off and not charging. Check out the vampire drain thread.
  3. Chris TX

    Chris TX Active Member

    Sep 30, 2013
    Dallas, TX
    If the car is very quiet and the AC compressor is going, it will make a low thunking sound when it cycles on and off. A clacking noise during charging will be the contactors closing (you might actually hear two of them).
  4. AmpedRealtor

    AmpedRealtor Well-Known Member

    Jun 30, 2013
    Buckeye, AZ
    Best to have your service center check it out. If this happens when you step on the pedal from a full stop, I'll hazard to guess that you are going to need a new battery because you may have that dreaded contactor issue that results in total failure at some point. This is why you should have service check it out instead of relying on forum diagnosis. It could be nothing or it could be pretty serious. Best to let the pros handle it.
  5. tezco

    tezco Sig P85

    Nov 9, 2012
    Amped is talking about what has been described in multiple treads as the "dreaded clunk". All owners should read about this, even though it is an extremely rare occurance. Main takeaway if your clunk uncouples the mains is to pull off the road, chock the wheels and put the car in jack and tow mode before the juice to the 12V runs out.

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