Analog Devices MAX17048 battery fuel gauge

The max17048 platform allows you to monitor the remaining capacity of a lithium-ion battery with an Analog Devices MAX17048 or MAX17049 fuel gauge (datasheet) in ESPHome. The ModelGauge algorithm in the chip tracks the state of charge over a wide range of charge and discharge profiles without a sense resistor or relearn cycles. The MAX17048 monitors one cell and the MAX17049 two cells in series; the two chips are otherwise the same. It uses the I²C Bus for communication.

NOTE

The voltage is scaled for the MAX17048. On a MAX17049, whose voltage step is doubled for its two cells, battery_voltage is therefore the average voltage per cell rather than the pack voltage; a multiply: 2 filter gives the pack voltage.

Adafruit MAX17048 LiPoly / LiIon fuel gauge and battery monitor

# Example configuration entry
sensor:
  - platform: max17048
    id: max17048_id
    battery_voltage:
      name: Battery Voltage
    battery_level:
      name: Battery Level

Configuration variables

• battery_voltage (Optional): The cell voltage in volts. All options from Sensor.
• battery_level (Optional): The state of charge in percent. All options from Sensor.
• rate (Optional): The rate at which the cell is charging or discharging, in percent per hour, positive while charging. All options from Sensor.
• address (Optional, int): The I²C address of the device. Defaults to 0x36.
• update_interval (Optional, Time): How often to read the gauge. Defaults to 60s.

If the gauge does not answer when the device starts, for example on an Adafruit Feather that switches the I²C power on after boot, the component sets a warning and tries again on every update until the gauge answers. The gauge’s CONFIG register keeps its value while the battery is connected; a value left by other firmware is logged as a warning and written back to the power-up default.

max17048.sleep_mode Action

This action puts the gauge into sleep mode, where it draws less than 1 µA. Call it just before the device enters deep sleep. When the device starts again, the component wakes the gauge.

on_...:
  then:
    - max17048.sleep_mode: max17048_id
    - deep_sleep.enter:
        id: deep_sleep_1
        sleep_duration: 20min

Configuration variables:

• id (Required, ID): The ID of the MAX17048 sensor.

NOTE

While the gauge sleeps it stops measuring, so the sensors keep publishing the last values. Only a restart of the device wakes it, so only call sleep_mode when the device is about to enter deep sleep.

The gauge also cannot track self-discharge while it sleeps. The datasheet recommends its automatic hibernate mode, which draws about 3 µA and needs no action, for devices that can afford that current.

Waking from sleep can raise a false low-battery alert in the gauge; the component clears it shortly after waking.

See Also

• I²C Bus
• MAX17043 battery fuel gauge
• MAX17048 product page