Intermittent Vehicle Standby battery drain

[redintegra]

I park in attached garage with sentry mode off and never open the app to wake the car up but sometimes I lose 2 to 3 percent battery over the span of several hours, all in vehicle standby. In one stance the car was plugged in. I haven't figured out a pattern as to why this happens.

Any explanations or suggestions? Thanks!

 

[E90alex]

Often it’s just from the BMS recalibrating. Don’t worry about it. Sometimes it even goes up.

 

[Bp25]

Do you have lead acid 12v battery? In another thread about 12v battery, it was mentioned that when the 12v can’t hold charge, the car will wake up to charge it. Just another possibility.

 

[redintegra]

Do you have lead acid 12v battery? In another thread about 12v battery, it was mentioned that when the 12v can’t hold charge, the car will wake up to charge it. Just another possibility.

How do I check?

 

[Bp25]

How do I check?

I can’t find that thread right now but I bought this device from Amazon: QUICKLYNKS Auto Battery Monitor BM2 Bluetooth 4.0 12V Device Car Battery Tester
This shows a history graph of battery voltage and if you see frequently going up to 14v when the car is supposed to sleep, it indicates that the car is waking up to charge the 12v.
The other way is to use Tesla widget on phone (not the app) to monitor how long the car has been sleeping. I am not sure how dependable this method is.

 

[kimwin]

I just experienced same Soc% loss over 24 hours period. The battery was charged to 50% (by wrong setting, should be 100%), car parked in garage.
Next day (24 hours), Soc loses 3.5% due to vehicle standby, 0% everywhere else. Mine is a M3 2023 with the 16V battery, not 12V.
The screen shows: "keep the car plugged in to avoid energy loss" !!!
Well keeping the car plugged in will of course consumes home electricity. From 3pm till midnight (peak period), the electricity rate in my area is high.
To avoid this high electricity rate, I can only keep it plugged in from 12am till 3pm !!!
Maybe it's best to turn off the circuit breaker that feed the Wall Connector during the peak hours.
Is this OK to leave the car plugged in with the circuit breaker OFF (at the panel) ?

 

[E90alex]

Do you have sentry mode on? Or keep opening and closing the car doors? Or keep opening the Tesla app?

If you’re not doing any of that it’s most likely just the battery computer readjusting and it’s not really losing that much.

The car doesn’t constantly pull power just because it’s plugged in. Even if it would pull 3.5% worth of battery from the wall, that’s like 2kWh on a Model 3 RWD. That’s like 60 cents on PG&E plan EV2-A.

If you want to unplug it, then unplug it at the car. Circuit breakers are not meant to be constantly flipped on and off like a light switch. If you have a Tesla Wall Connector you can set a window as to when charging is allowed.

 

[DrDiesel1]

Do you have cabin overheat protection on ? I leave my car plugged in and I hear
it running the heat pump to keep the HVB conditioned.

 

[kimwin]

Circuit breakers are not meant to be constantly flipped on and off like a light switch. If you have a Tesla Wall Connector you can set a window as to when charging is allowed.

I only turn ON the circuit breaker when I schedule it for charging (once a week or once every 10th day). Otherwise, the circuit breaker is OFF.

 

[kimwin]

Do you have cabin overheat protection on ?

No , I don't.

I leave my car plugged in and I hear
it running the heat pump to keep the HVB conditioned.

In this case, the % of energy used for battery conditioning should show a few % ? Mine shows 0%.
My plain guess: leaving the car plugged in prevents energy loss while parking at the cost of electricity usage.
This does not save anything !!! My driving is mostly less than 30 miles a day, occasionally a long distance (100-150 miles).
I avoid open the Tesla app, only open the door or the trunk when I am about to drive.