EV Preheating in Winter

Easy 15 min

Never step into a freezing car again! This guide shows how to automatically preheat your electric vehicle when temperatures drop - while saving battery by only heating when necessary.

Why Automatic Preheating?

Benefit	Description
Comfort	Warm cabin and defrosted windows every morning
Battery	Preheating while plugged in uses grid power, not battery
Range	Preheated battery = better range in cold weather
Safety	Clear windows without scraping

Save your battery

When the car is plugged in, preheating uses power from the grid instead of the battery. Automation ensures you only heat when necessary!

What You Need

Component	Description
Home Assistant	With Tesla, Polestar, VW or other EV integration
EV Integration	Tesla Custom Integration, Volkswagen We Connect, Polestar API, etc.
Mobile phone	For notifications

Supported Electric Vehicles

Brand	Integration	HACS
Tesla	Tesla Custom Integration	Yes
Volkswagen/Audi/Skoda	Volkswagen We Connect ID	Yes
Polestar	Polestar API	Yes
BMW	BMW Connected Drive	Yes
Mercedes	Mercedes ME	Yes
Hyundai/Kia	Hyundai/Kia Connect	Yes
Renault	Renault ZE Services	Yes

Tesla example

This guide uses Tesla as an example, but the principles are the same for other brands. Adjust entity_ids for your car.

Entities You Get

With a typical EV integration you get these entities:

Entity	Type	Description
climate.car_climate	Climate	Turn climate on/off
sensor.car_inside_temperature	Sensor	Interior temperature
sensor.car_outside_temperature	Sensor	Exterior temperature
sensor.car_battery_level	Sensor	Battery level in %
sensor.car_charging	Sensor	Charging status
select.car_seat_heater_*	Select	Seat heater (off/low/medium/high)

Automations

1. Automatic Heating Below Freezing

The most important automation - turn on climate automatically when it’s freezing:

automation:
  - alias: "Car: Heating below 0 degrees"
    description: "Turns on car climate when temperature is below 0°C for 1 minute"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.car_inside_temperature
        below: 0
        for:
          minutes: 1
    condition:
      # Only if battery is above 40%
      - condition: numeric_state
        entity_id: sensor.car_battery_level
        above: 40
    action:
      # Turn on climate
      - service: climate.set_preset_mode
        target:
          entity_id: climate.car_climate
        data:
          preset_mode: "on"
      # Wait 15 minutes
      - delay:
          minutes: 15
      # Turn off again
      - service: climate.set_preset_mode
        target:
          entity_id: climate.car_climate
        data:
          preset_mode: "off"

Battery condition

We check that the battery is above 40% before heating. Adjust this value to your needs - you don’t want to drain the battery completely!

2. Cold Car Notification (at night)

Get notified if the car gets too cold at night:

automation:
  - alias: "Car: Cold at night"
    description: "Sends notification when car is below 5°C at night"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.car_inside_temperature
        below: 5
    condition:
      - condition: time
        after: "22:00:00"
        before: "07:00:00"
    action:
      - service: notify.mobile_app_your_phone
        data:
          title: "Car is cold"
          message: >
            Interior temp: {{ states("sensor.car_inside_temperature") }}°C
          data:
            tag: "car_cold"

3. Cooling in High Temperature (summer)

Bonus: Keep the car cool in summer:

automation:
  - alias: "Car: Cooling above 30 degrees"
    description: "Turns on AC when temperature is above 30°C"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.car_inside_temperature
        above: 30
        for:
          seconds: 20
    condition:
      - condition: numeric_state
        entity_id: sensor.car_battery_level
        above: 40
    action:
      - service: climate.set_temperature
        target:
          entity_id: climate.car_climate
        data:
          temperature: 20
          hvac_mode: "cool"

  - alias: "Car: Turn off cooling below 20 degrees"
    description: "Turns off AC when temperature is below 20°C"
    mode: single
    trigger:
      - platform: numeric_state
        entity_id: sensor.car_inside_temperature
        below: 20
        for:
          minutes: 2
    action:
      - service: climate.turn_off
        target:
          entity_id: climate.car_climate

4. Morning Preheating on Weekdays

Preheat the car automatically before work:

automation:
  - alias: "Car: Morning preheating"
    description: "Preheats the car at 07:00 on weekdays when cold"
    mode: single
    trigger:
      - platform: time
        at: "07:00:00"
    condition:
      - condition: time
        weekday:
          - mon
          - tue
          - wed
          - thu
          - fri
      # Only if it's cold
      - condition: numeric_state
        entity_id: sensor.car_inside_temperature
        below: 10
      # Only if battery is OK
      - condition: numeric_state
        entity_id: sensor.car_battery_level
        above: 30
    action:
      - service: climate.set_preset_mode
        target:
          entity_id: climate.car_climate
        data:
          preset_mode: "on"
      - service: notify.mobile_app_your_phone
        data:
          title: "Car is preheating"
          message: >
            Temp: {{ states("sensor.car_inside_temperature") }}°C
            → Ready in 15 min
      - delay:
          minutes: 15
      - service: climate.set_preset_mode
        target:
          entity_id: climate.car_climate
        data:
          preset_mode: "off"

5. Seat Heaters When Cold

Turn on seat heaters automatically with climate:

automation:
  - alias: "Car: Seat heaters when freezing"
    description: "Turns on seat heaters when climate activates in freezing conditions"
    mode: single
    trigger:
      - platform: state
        entity_id: climate.car_climate
        to: "heat_cool"
    condition:
      - condition: numeric_state
        entity_id: sensor.car_inside_temperature
        below: 5
    action:
      # Turn on seat heaters on both front seats
      - service: select.select_option
        target:
          entity_id: select.car_seat_heater_left
        data:
          option: "high"
      - service: select.select_option
        target:
          entity_id: select.car_seat_heater_right
        data:
          option: "high"
      # Set to medium after 5 min
      - delay:
          minutes: 5
      - service: select.select_option
        target:
          entity_id:
            - select.car_seat_heater_left
            - select.car_seat_heater_right
        data:
          option: "medium"

Dashboard Cards

Car Status Card

type: entities
title: "EV Status"
entities:
  - entity: sensor.car_inside_temperature
    name: Interior temp
    icon: mdi:thermometer
  - entity: sensor.car_outside_temperature
    name: Exterior temp
    icon: mdi:thermometer
  - entity: sensor.car_battery_level
    name: Battery
    icon: mdi:battery
  - entity: climate.car_climate
    name: Climate
  - entity: sensor.car_charging
    name: Charging

Climate Control Card

type: thermostat
entity: climate.car_climate
name: Car Climate
features:
  - type: climate-preset-modes
    preset_modes:
      - "off"
      - "on"
      - "dog"
      - "camp"

Gauge Card

type: gauge
entity: sensor.car_inside_temperature
name: Cabin Temperature
unit: "°C"
min: -20
max: 50
severity:
  green: 15
  yellow: 25
  red: 35
needle: true

Tesla-Specific Preset Modes

Tesla has special preset modes:

Mode	Description
off	Climate off
on	Normal heating/cooling
dog	Dog mode - maintains comfortable temp and shows message on screen
camp	Camp mode - maintains climate and power to devices

# Activate dog mode
service: climate.set_preset_mode
target:
  entity_id: climate.car_climate
data:
  preset_mode: "dog"

Dog Mode

Perfect when leaving your dog in the car briefly. The screen shows “My owner will be back soon” and the temperature is kept comfortable.

Helpers for Advanced Control

Input for Heating Time

input_datetime:
  car_heating_time:
    name: "Car heating time"
    has_date: false
    has_time: true
    icon: mdi:car-clock

Input for Minimum Battery

input_number:
  car_min_battery_heating:
    name: "Minimum battery for heating"
    min: 20
    max: 80
    step: 5
    unit_of_measurement: "%"
    icon: mdi:battery-alert

Tips

Optimize Battery Usage

1. Preheat while plugged in - Use grid power, not battery
2. Set time limit - 15-20 minutes is typically enough
3. Check battery first - Avoid heating at low battery
4. Use seat heaters - Uses less power than cabin heating

Winter Range Tips

Tip	Effect
Preheat while plugged in	+10-20% range
Use seat heaters instead of cabin heat	+5% range
Keep battery above 20%	Protects battery

Troubleshooting

Car not responding?

1. Check that the car has internet connection
2. Verify the integration is active
3. Try “waking” the car first via button.car_wake
4. Check the Tesla/car app works

Automation not running?

1. Check the conditions (battery, temperature)
2. View automation trace in Home Assistant
3. Verify entity_ids are correct
4. Check that the automation is enabled

Too much battery usage?

Reduce heating time from 15 to 10 minutes, or set a higher battery threshold (e.g., 50% instead of 40%).

Next Steps

Electricity Price Integration

Charge the car when electricity is cheapest.

Electricity prices →

Low Battery Alert

Get notified before sensors run out.

Low battery →