Does the battery keep its charge if I don’t use the car?

According to Tesla, you should expect to lose about 1% of range per day at minimum just for basic housekeeping tasks the car does, specifically around managing the battery condition. It is possible you will see higher battery drain (commonly known as “phantom drain”) depending on the environment and what else you have configured, knowingly or otherwise.

Common things to look out for are:

• Sentry Mode can drain up to 10-20% per day depending on how many times the sensors detect something to report.
• Keeping the cabin temperature at a set point (Dog Mode, Camper Mode, just keeping the climate control on) will be a significant source of drain, depending on how different the interior temperature is to the outside temperature.
• Having Summon on Standby has been known to cause significant (1-2% per hour?) drain.
• Third party apps that keep the car awake will by definition drain the battery a little bit faster, because the car is always awake.

This does mean you should prepare for this if you have to leave the car unplugged for days at a time (such as when traveling). If there is no way to leave the car plugged in even to a Level 1 charger, it’s a good idea to turn off features that aren’t needed, refrain from checking on the car every hour to see how it’s doing, and maybe arrange to have someone plug it in if possible.