Preheat your car via Google Calendar

Never experience a uncomfortable seat ever again

I live in Canada 🇨🇦. It’s too warm 🥵 in Summer and too cold 🥶 in Winter.

You may not understand but it’s the best place on Earth 🌎️.

Did you ever get in a car and it was uncomfortable, and by the time you completed your commute, it just become comfortable?

Did you ever get out of the gym during cold days, all sweaty, and wish you created a schedule so the car would be already warm?

For those having to do a regular car commute, one can increase their comfort with preconditioning the car. While preconditioning a ICE car wastes gas inefficiently, preconditioning an electric car doesn’t waste as much energy.

I integrated my electric car’s thermostat with a Google Calendar with Home Assistant. It’s magnificent.

Here’s how:

Setup

• Google Calendar setup
  • Create a new dedicated calendar at calendar.google.com.
    • Click the “+” aside “Other calendars” on the left side at and chose “Create new calendar”.
    • I personally use the GMail account I created for the car to use YT Premium Family in the console.
  • Share this calendar to you and your partner in “Settings and sharing” in the 3 dots menu.
  • Add this calendar to your Calendar android app as a secondary calendar ← the trick that really makes it great.
• Install Home Assistant (HA).
  • Install Tesla’s integration github.com/alandtse/tesla.
  • Connect Home Assistant to your car.
• Install Google Calendar HA integration.
  • It’s involved because you need to create a GCP project. It’s worth it because you can reuse the trick for other uses as I describe below. Don’t desperate!
• Connect HA to the calendar you created above, either using the car’s GMail account or your personal one where the calendar is visible.
• Create a Script in scripts.yaml or preferably via the web UI. Mine looks like this:

  condition_car:
    sequence:
    - device_id: 123456
      domain: climate
      entity_id: climate.<car_name>_hvac_climate_system
      type: set_hvac_mode
      hvac_mode: heat_cool
    - service: climate.set_temperature
      data:
        temperature: 24
        hvac_mode: heat_cool
      target:
        entity_id: climate.<car_name>_hvac_climate_system
    - device_id: 123456
      domain: climate
      entity_id: climate.<car_name>_hvac_climate_system
      type: set_preset_mode
      preset_mode: Normal
    - device_id: 123456
      domain: select
      entity_id: select.<car_name>_heated_seat_left
      type: select_option
      option: High
    - device_id: 123456
      domain: select
      entity_id: select.<car_name>_heated_seat_right
      type: select_option
      option: High
    - type: turn_on
      device_id: 123456
      entity_id: switch.<car_name>_heated_steering
      domain: switch
    mode: single
    alias: Prewarm car
    icon: mdi:car-defrost-front
  

  • I tune it in Spring and Fall. Obviously I turn off seat heater in Spring. I set the preset to Defrost during the worst of Winter.
• Create an Automation in automations.yaml or preferably via the web UI. Mine looks like this:

  - id: '1234'
    alias: 'Calendar: Prewarm car'
    description: ''
    trigger:
    - platform: state
      entity_id:
      - calendar.<name_of_your_calendar>
      to: 'on'
    condition:
    - type: is_battery_level
      condition: device
      device_id: 123456
      entity_id: sensor.<car_name>_battery
      domain: sensor
      above: 55
    action:
    - service: script.condition_car
      data: {}
    mode: single
  

  One tweak is to skip the preheat if the battery level is too low, as a safety measure.
• In your Lovelace dashboard, add an Entity that links to the script. This enables doing a quick turn on. It’s much faster than going to the Tesla android app because it’s fully asynchronous. You don’t risk clicking the lock or charge port button by accident. This happened to me a few times.

Did you integrate Home Assistant with other car brands?

Note that you will need a recent version of the Tesla integration (v3.x) and Home Assistant (2022.10 or later). It works on older versions but the type changed.

Extras

I reuse the calendar trick for light-based morning alarms!

I personally only need it on kids' school days, and they have a lot of random days off. I created a dedicated Google Calendar that contains a recurring event at the start of the school year and I don’t have to think about it for the rest of the year.

I use this calendar to drive lights 💡 in my bedroom that I slowly turn up over the course of 30 minutes, which makes the waking process very smooth.

What do you think?

I’d love to hear about it on Mastodon at pourparler.ca/@maruel!

Thanks a lot to Alan Tse for the awesome Tesla Home Assistant integration, Allen Porter for maintaining the Google Calendar integration and all the Home Assistant team for such a great project! ❤️