Your Tesla loses range when parked caused by something called "Vampire battery drain" or just "Vampire drain". This can vary from a few miles per day to quite significant amounts depending on the settings in the car and can be a problem if leaving your car while on holiday. This guide tells you how you can minimise Tesla vampire drain.
Your Tesla never completely goes to sleep. It contains lots of computer systems that do various function from monitoring the health of the battery, listening to see if Tesla are trying to connect to the car over the air, being ready to open the doors when you walk up to the car. The number of computer systems that are running can vary when the car is parked and the trade off it usually between responsiveness of the car and the amount of power consumed. You may sometimes see the car say "powering up" or your the App saying "Waking up car", essentially you are waiting for the relevant computer to fire up.
Most of the time this isn't really a problem as the loss is relativity small over a short period of time and many people plug in to charge over night and do not see the impact of vampire drain although over the course of a year it can be quite considerable. Where the issue is most noticeable is when leaving the car for more than a couple of days and not on charge. A typical example might be at an airport long stay car park when going off on a 2 week vacation. The wrong settings could mean you return to a flat battery. This has also become more of a problem with the introduction of features like sentry mode and the increased number of 3rd party applications that may keep pinging the car and are not good at respecting the car going to sleep.
Note 1: Discharging the HV (main) Battery to 0% may permanently damage it. To protect against a complete discharge the car will go into self protection mode but even this has a finite duration of a couple of months and would need charging before use.
Note 2: The HV battery supplies power to the 12V battery. If the 12V battery also becomes depleted then even opening the car will be a problem. Access tot he 12V battery is possible and this battery can be boosted allowing the car to start charging but in practice the car will still need recovering to a suitable charger
Avoid using any 3rd party app that poll the car for information such as Teslafi. While many apps do work better and try not to wake the car, partly supported by Tesla introducing a Wake request to the API, these 3rd party apps do not always get it right. As an aside, we DO NOT recommend any 3rd party app that retains your details. The Tesla security is not sufficient to discriminate, the introduction of Multi factor authentication (MFA) only provides limited protection as Tesla also issue renewal tokens that avoid the subsequent need to enter your details and MFA code (ie once you've given a valid MFA code to a 3rd party app it can maintain access indefinitely unless you change your password) and some of the developers don't sign up to standards such as the European General Data Protection Act which we believe are relevant to cars with level of logging Tesla provide. Irrespective, the polling of the car will keep computers awake and can increase the vampire drain considerably.
Also avoided excessive use of the Tesla App. Every time you access the car data you are starting up computers and increasing the drain on the battery. Owners sometimes like to check in on the car every few hours when on holiday especially if they are worried about the battery drain and this will just accelerate the vampire drain.
While a great option, this is a simply dreadful option with respect to vampire drain. The car is kept in a high state of power consumption and is the single most important thing you should turn off to minimise battery drain.
Within the car there is a power management option for energy saving and Always connected. The most efficient combination if Energy Saving = On and Always connected left unticked.
In day to day use, many leave Energy Saving off as this is still reasonably efficient.
Simply NEVER use Smart preconditioning. It rarely works well and can result in the car heating itself up even when you have no intention of using it.
Dog mode, Camping mode etc all use energy from the battery, and while fine for short periods, they should be left off when leaving the car for any length of time.