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What's up with whirring sound and battery drain (which is actually normal)?

Before even having my Model 3 I was reading some post about "vampire" drain and it was kinda concern, as I drive little and most of my charging would be compensation of that battery drain. Some owners complain about drain around 10-12 miles a day. Owner manual states that drain is about 1% of the range, so for Model 3 with long range battery it is about 3 miles a day. Finally when I got a car I started to measure the drain. My car stays in garage, sometimes 3-4 days with no wake up. temperature in garage was about 72-76 F, perfect for the battery I believe. Drain was about 3-4 miles a day, which looks like normal. So, basically there is nothing worry about. You ask, so what is this post about?
Probably everybody noticed that not loud whirring sound which appear whenever you wake up a car. I am not sure what it is, sound like some pump, could be in a coolant/heating system. I wonder why that pump start working every time car woke up. I thought that pumping make temperature even for all battery cells, but I am only guessing. And even then, why start pumping if driving not even happened yet? After I put car in garage even if I barely drove (less than 1 mile), whirring sound will continue long time after (I think about hour, did not measure the time).
If we calculate how much energy lost for drain we will see that it is not that much, about 0.75KWH a day. It means that drain is about 31W. Li-ion cells loose much less than 1% a day. Taking into consideration that bluetooth, and WiFi take very little, I think that pumping take a biggest part. Of course there some other loads, like supporting 12V battery, but 12V battery generally just idle, and 12V loads supported by DC2DC from high voltage battery, so when car just stays, 12V battery does not need recharging in normal situation.
So, why pump starts working every time car woke up and do not stop long time after car stops, even if car woke up just for the minute? I have a feeling that there is something to improve.
 

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