Include charging state for powerwall (#33432)

* Switch to binary sensor for charging status per review

* Powerwall charging margin of error is much higher than expected

homeassistant/components/powerwall/binary_sensor.py

@@ -1,9 +1,10 @@
-"""Support for August sensors."""
+"""Support for powerwall binary sensors."""
 import logging
 
 from tesla_powerwall import GridStatus
 
 from homeassistant.components.binary_sensor import (
+    DEVICE_CLASS_BATTERY_CHARGING,
     DEVICE_CLASS_CONNECTIVITY,
     BinarySensorDevice,
 )
@@ -13,13 +14,16 @@ from .const import (
     ATTR_GRID_CODE,
     ATTR_NOMINAL_SYSTEM_POWER,
     ATTR_REGION,
+    CHARGING_MARGIN_OF_ERROR,
     DOMAIN,
     POWERWALL_API_DEVICE_TYPE,
     POWERWALL_API_GRID_STATUS,
+    POWERWALL_API_METERS,
     POWERWALL_API_SERIAL_NUMBERS,
     POWERWALL_API_SITE_INFO,
     POWERWALL_API_SITEMASTER,
     POWERWALL_API_STATUS,
+    POWERWALL_BATTERY_METER,
     POWERWALL_COORDINATOR,
 )
 from .entity import PowerWallEntity
@@ -42,6 +46,7 @@ async def async_setup_entry(hass, config_entry, async_add_entities):
         PowerWallRunningSensor,
         PowerWallGridStatusSensor,
         PowerWallConnectedSensor,
+        PowerWallChargingStatusSensor,
     ):
         entities.append(
             sensor_class(
@@ -131,3 +136,32 @@ class PowerWallGridStatusSensor(PowerWallEntity, BinarySensorDevice):
     def is_on(self):
         """Grid is online."""
         return self._coordinator.data[POWERWALL_API_GRID_STATUS] == GridStatus.CONNECTED
+
+
+class PowerWallChargingStatusSensor(PowerWallEntity, BinarySensorDevice):
+    """Representation of an Powerwall grid status sensor."""
+
+    @property
+    def name(self):
+        """Device Name."""
+        return "Powerwall Charging"
+
+    @property
+    def device_class(self):
+        """Device Class."""
+        return DEVICE_CLASS_BATTERY_CHARGING
+
+    @property
+    def unique_id(self):
+        """Device Uniqueid."""
+        return f"{self.base_unique_id}_powerwall_charging"
+
+    @property
+    def is_on(self):
+        """Grid is online."""
+        return (
+            self._coordinator.data[POWERWALL_API_METERS][
+                POWERWALL_BATTERY_METER
+            ].instant_power
+            < CHARGING_MARGIN_OF_ERROR
+        )

homeassistant/components/powerwall/const.py

@@ -42,6 +42,12 @@ POWERWALL_GRID_ONLINE = "SystemGridConnected"
 POWERWALL_CONNECTED_KEY = "connected_to_tesla"
 POWERWALL_RUNNING_KEY = "running"
 
+POWERWALL_BATTERY_METER = "battery"
+
+# We only declare charging if they are getting
+# at least 40W incoming as measuring the fields
+# is not an exact science because of interference
+CHARGING_MARGIN_OF_ERROR = -40
 
 MODEL = "PowerWall 2"
 MANUFACTURER = "Tesla"

tests/components/powerwall/test_binary_sensor.py

@@ -52,3 +52,13 @@ async def test_sensors(hass):
     # Only test for a subset of attributes in case
     # HA changes the implementation and a new one appears
     assert all(item in state.attributes.items() for item in expected_attributes.items())
+
+    state = hass.states.get("binary_sensor.powerwall_charging")
+    assert state.state == STATE_ON
+    expected_attributes = {
+        "friendly_name": "Powerwall Charging",
+        "device_class": "battery_charging",
+    }
+    # Only test for a subset of attributes in case
+    # HA changes the implementation and a new one appears
+    assert all(item in state.attributes.items() for item in expected_attributes.items())