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833hz at approx 1 volt on 12 Volt circuit

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I have been tracking down a whine clearly audible over the sound of music, I suspected it came through the speakers so I got myself a DSO digital storage oscilloscope, sure enough there is a an occasional tone on the 12Volt line related to motor load.
I have not yet persuaded myself it is worth ripping apart the upholstery to get at the speaker connections.

Recent service visit put it down as normal for “permanent magnets”! The tech had promised a recording of the speaker output underload, Sadly no such data forth coming.

They are actually attributing the whine to motor mounting blocks that have been redesigned in the Model X.
I look forwards to the arrival of the redesigned blocks for the Model S.
Though being new to Tesla, I am unsure of how likely they are to do a retro active refit.

To be clear I am still totally in love with my new Wheels, I purchased the DSO in order to help an amazing car reach total perfection.

I still think that the excessive noise on the 12V line is the cause of my tone.
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The 12 volt battery is charged by a DC to DC converter from the high voltage battery. It probably uses a switching power supply to do this.
Is the tone there when the battery is not being charged? If the battery voltage is 12.7 volts or lower it is not being charged. The car has to be off for the charging to stop. While off my car charges the 12 volt battery from 50% to 100% four times a day.