Cheers Jason,
Car is a SR+ 21 Reg 55kWh battery.
I never use Sentry mode.
Journeys are generally 5 miles twice a day and 1.5 miles twice a day every day.
Preheating is on Auto Schedule (i think about 30mins)
There was a time that scheduled departure was only usable while charging i.e. so only if the car was plugged in. I assume that is no longer the case ( i never use it) . But either way 30minutes is way way longer than is needed for your journeys. It may be optimal if the car is plugged in and you are trying to maximise range for a long journey but for heating up the cabin for a short journey that can be done in 5-10 minutes even in cold weather. Pre heat is able to draw in the region of 7kw I believe so in the recent cold you could have been using as much as 3-4kwh with a 30 minute preheat.
If you want to use a scheduled preheat I recommend getting a third party app such as Tessie which is much more flexible.
You said 55kwh battery? is that usable capacity? if so then 81% of 55 = 44.55.
Car said it used 19KWh so looks like we are chasing about 25 missing kwh
you said you covered 49 miles and looks like your daily journeys are 13 miles so I am going to assume we are talking about 3days here so your preheat could
have cost you 9-12 kwh based on my estimate above so that would take us down to about 13kwh "missing"
Did you manually preheat for any period before the other trips? if so that could account for some.
The other thing to consider is even if you don't use sentry then sometimes something happens that prevents the car from sleeping. If the car does not sleep it will use 5kwh+ per day just running the computers. Do you use any 3rd party software that could be keeping the car awake? have you ever used your Tesla credentials to log into anything?
So at this stage I would say something like the above is more likely than a battery fault.
What I would recommend is next time you charge monitor the battery %
check it
before preheat
after pre heat
after driving
at the start of the next preheat/drive
That way you can see if the charge is being lost during driving, during preheat, between drives.
You may be able to get the answer from the energy graph in the car. If the car is losing charge between drives this will show up as shear drops on the graph where the battery drops but no miles are covered like this:
You will definitely see this for preheat but how much and whether you also get this when you don't preheat will tell you a lot
and then forgetting to switch off the preheat!
