Battery Drain

[Droschke]

Sits under car port. Does have cabin overheat protection.

Here's the results from sitting for 24 hrs. Not plugged in, no auto update enabled, no summon, didn't check Tesla app even once.

Low and behold. Only lost 1 mile and went from 70% charge to 69% !!!
First time ever!!! Wow. Wish I had a logical answer as to why it lost almost no miles and percentage rate.

As mentioned earlier, if you charge some older battery packs (including mine) to over 70% of charge the fans and pumps run for hours, hence losing miles.

What I also have also found out is that leaving the car plugged in increases the vampire drain. I used to have the car always plugged in while parked in the garage and since early this year I noticed a drain of up to 8 miles per 24 hours while the car was parked and plugged. Have switched to leave it unplugged and now I only lose 2 miles, like what you just experienced, per 24 hours. It would be interesting if you repeat the same test while plugged in for 24 hours to see if your drain is higher.

Here is the thread I started with lots of data:

High Vampire Drain

I had my 12 volt battery changed at SC three years ago (the odometer difference between then and now is only ~4500 miles). My typical vampire drain used to be about 2-3 miles a day. I now notice to be 6-8 miles a day, with the car not driven and parked in the garage. I don’t use any 3rd-party...

teslamotorsclub.com

 

[PCMc]

My car sits unused for upwards of 15 weeks at a time. It's always plugged in so I can remotely manage periodic recharging without needing anyone to go to the car for me. I've been doing this for over last 2 years. I've never seen any impact of leaving it plugged in, but with the charging setpoint moved down to 50% such that the car does not recharge until I trigger it to raise back up. I've done this on my mid-2016 MS90D now with both MCU1 and MCU2. My 12 volt battery is now over 4 years old for reference.

The latest result that @Penn saw with SOC set at 70% is totally what I'd expect. For my car now with MCU2 I'll see about 2% loss ever 3 days. that says I can charge car to 80%, lower the SOC trigger to 50%, and go about 45 days before it's down to 51-52% range which is my threshold where my monitoring program automatically detects it's time to recharge, raises the setpoint back up to 70% or 80%, to trigger it to recharge.

 

[Wol747]

Does anyone know what hysteresis there is with the HV battery when plugged in?
I would guess that if there's a very small delta between the SOC and the "switch on charging" point the thing would fire up very often with the associated drain which would probably be greater than if there was a bigger "gap".

 

[ucmndd]

Does anyone know what hysteresis there is with the HV battery when plugged in?
I would guess that if there's a very small delta between the SOC and the "switch on charging" point the thing would fire up very often with the associated drain which would probably be greater than if there was a bigger "gap".

In my experience it’s like ~3%. If my car loses 3% SoC from the set point, it will charge during the next scheduled window.

 

[PCMc]

In my experience it’s like ~3%. If my car loses 3% SoC from the set point, it will charge during the next scheduled window.

My experience is this is a function of whether you are using schedule charging. My experience when I did not use scheduled charging, left the plugged in, then it would periodically top up the car as soon as the SOC dropped below the setpoint.

I would guess that if there's a very small delta between the SOC and the "switch on charging" point the thing would fire up very often with the associated drain which would probably be greater than if there was a bigger "gap".

Actually in this case it will give the appearance that there is virtually zero drain as the battery is being topped up potentially every multiple times during the day. Unless you have some other external logging means to see that, you're blind as the indicated SOC or rated miles appear unchanged.

 

[Wol747]

My experience is this is a function of whether you are using schedule charging. My experience when I did not use scheduled charging, left the plugged in, then it would periodically top up the car as soon as the SOC dropped below the setpoint.



Actually in this case it will give the appearance that there is virtually zero drain as the battery is being topped up potentially every multiple times during the day. Unless you have some other external logging means to see that, you're blind as the indicated SOC or rated miles appear unchanged.

Understood. But obviously the drain is still there. You will see it if you are NOT plugged in since the HV >12v energy transfer will show as percentage or distance loss which may be translated into energy from the grid if plugged in (plus charger losses.)