Power Saving

BTHome devices are often battery-powered. These configurations help minimize power consumption.

CPU Frequency (ESP32)

Lower the CPU frequency from 240MHz (default) to 80MHz for significant power savings:

esp32:
  board: seeed_xiao_esp32s3
  framework:
    type: esp-idf
    sdkconfig_options:
      CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_80: y

Available frequencies:

• CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_240 - 240MHz (default, highest performance)
• CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_160 - 160MHz (balanced)
• CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_80 - 80MHz (lowest power)

When to use 80MHz

80MHz is sufficient for most BTHome applications since BLE advertising and sensor reading don’t require high CPU speeds.

WiFi Power Saving

Combine disabling WiFi on boot with power save mode for maximum savings:

wifi:
  enable_on_boot: false
  ap: {}
  power_save_mode: HIGH

Options

enable_on_boot: false - WiFi radio stays off at startup. BLE continues to work independently.

power_save_mode - Controls WiFi power consumption when enabled:

• NONE - No power saving (default)
• LIGHT - Light power saving, minimal latency impact
• HIGH - Maximum power saving, higher latency

OTA Updates

With enable_on_boot: false, OTA updates won’t work until WiFi is enabled programmatically. Flash via USB or add a mechanism to enable WiFi when needed.

Deep Sleep

For maximum battery life, use deep sleep to power down the ESP32 completely between readings:

deep_sleep:
  run_duration: 1min    # Stay awake for 1 minute
  sleep_duration: 5min  # Sleep for 5 minutes

During deep sleep, the ESP32 consumes only ~10µA. The device will:

1. Wake up from deep sleep
2. Initialize BLE and sensors
3. Broadcast sensor data for run_duration
4. Enter deep sleep for sleep_duration
5. Repeat

Advertising during wake window

Set your BTHome min_interval and max_interval to broadcast multiple times during the wake window. This ensures Home Assistant receives at least one update before the device sleeps.

Wake time considerations

Allow enough run_duration for BLE to initialize and broadcast several times. 30-60 seconds minimum is recommended.

Complete Low-Power Example

esphome:
  name: bthome-sensor
  friendly_name: BTHome Sensor

esp32:
  board: seeed_xiao_esp32s3
  framework:
    type: esp-idf
    sdkconfig_options:
      CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_80: y

logger:

wifi:
  enable_on_boot: false
  ap: {}
  power_save_mode: HIGH

esp32_ble:
  id: ble

sensor:
  - platform: internal_temperature
    id: temp
    update_interval: 60s  # Less frequent updates

bthome:
  min_interval: 30s  # Longer advertising interval
  max_interval: 60s
  tx_power: -6      # Lower TX power
  sensors:
    - type: temperature
      id: temp

Power Saving Checklist

Setting	Impact	Recommendation
Deep sleep	Very High	Use for battery devices (~10µA sleep)
CPU frequency	High	Use 80MHz for BLE-only devices
WiFi on boot	High	Disable with enable_on_boot: false
WiFi power save	Medium	Use power_save_mode: HIGH
Advertising interval	Medium	30s+ for battery devices
TX power	Medium	Lower if range permits
Sensor update interval	Low	Match to advertising interval
Logger	Low	Disable in production

Disabling Logger

For production deployments, disable logging to save additional power:

logger:
  level: NONE

Or remove the logger: section entirely.