Support for low battery state (and remaining time)

src/Vehicle/BatteryFact.json

@@ -46,5 +46,19 @@
     "type":             "float",
     "decimalPlaces":    2,
     "units":            "W"
+},
+{
+    "name":             "timeRemaining",
+    "shortDescription": "Time Remaining",
+    "type":             "int32",
+    "units":            "s"
+},
+{
+    "name":             "chargeState",
+    "shortDescription": "Charge State",
+    "type":             "uint8",
+    "enumStrings":      "Low Battery State Not Provided,Normal Operation,Low Battery State,Critical Battery State,Emergency Battery State,Battery Failed,Battery Unhealthy",
+    "enumValues":       "0,1,2,3,4,5,6",
+    "decimalPlaces":    0
 }
 ]

src/Vehicle/Vehicle.cc

@@ -1319,6 +1319,20 @@ void Vehicle::_handleBatteryStatus(mavlink_message_t& message)
     }
 
     _batteryFactGroup.cellCount()->setRawValue(cellCount);
+
+    //-- Time remaining in seconds (0 means not supported)
+    _batteryFactGroup.timeRemaining()->setRawValue(bat_status.time_remaining);
+    //-- Battery charge state (0 means not supported)
+    if(bat_status.charge_state <= MAV_BATTERY_CHARGE_STATE_UNHEALTHY) {
+        _batteryFactGroup.chargeState()->setRawValue(bat_status.charge_state);
+    } else {
+        _batteryFactGroup.chargeState()->setRawValue(0);
+    }
+    //-- TODO: Somewhere, actions would be taken based on this chargeState:
+    //   MAV_BATTERY_CHARGE_STATE_CRITICAL:     Battery state is critical, return / abort immediately
+    //   MAV_BATTERY_CHARGE_STATE_EMERGENCY:    Battery state is too low for ordinary abortion, fastest possible emergency stop preventing damage
+    //   MAV_BATTERY_CHARGE_STATE_FAILED:       Battery failed, damage unavoidable
+    //   MAV_BATTERY_CHARGE_STATE_UNHEALTHY:    Battery is diagnosed to be broken or an error occurred, usage is discouraged / prohibited
 }
 
 void Vehicle::_setHomePosition(QGeoCoordinate& homeCoord)
@@ -3247,6 +3261,8 @@ const char* VehicleBatteryFactGroup::_currentFactName =                     "cur
 const char* VehicleBatteryFactGroup::_temperatureFactName =                 "temperature";
 const char* VehicleBatteryFactGroup::_cellCountFactName =                   "cellCount";
 const char* VehicleBatteryFactGroup::_instantPowerFactName =                "instantPower";
+const char* VehicleBatteryFactGroup::_timeRemainingFactName =               "timeRemaining";
+const char* VehicleBatteryFactGroup::_chargeStateFactName =                 "chargeState";
 
 const char* VehicleBatteryFactGroup::_settingsGroup =                       "Vehicle.battery";
 
@@ -3267,6 +3283,8 @@ VehicleBatteryFactGroup::VehicleBatteryFactGroup(QObject* parent)
     , _temperatureFact              (0, _temperatureFactName,               FactMetaData::valueTypeDouble)
     , _cellCountFact                (0, _cellCountFactName,                 FactMetaData::valueTypeInt32)
     , _instantPowerFact             (0, _instantPowerFactName,              FactMetaData::valueTypeFloat)
+    , _timeRemainingFact            (0, _timeRemainingFactName,             FactMetaData::valueTypeInt32)
+    , _chargeStateFact              (0, _chargeStateFactName,               FactMetaData::valueTypeUint8)
 {
     _addFact(&_voltageFact,                 _voltageFactName);
     _addFact(&_percentRemainingFact,        _percentRemainingFactName);
@@ -3275,6 +3293,8 @@ VehicleBatteryFactGroup::VehicleBatteryFactGroup(QObject* parent)
     _addFact(&_temperatureFact,             _temperatureFactName);
     _addFact(&_cellCountFact,               _cellCountFactName);
     _addFact(&_instantPowerFact,            _instantPowerFactName);
+    _addFact(&_timeRemainingFact,           _timeRemainingFactName);
+    _addFact(&_chargeStateFact,             _chargeStateFactName);
 
     // Start out as not available
     _voltageFact.setRawValue            (_voltageUnavailable);

src/Vehicle/Vehicle.h

@@ -255,6 +255,8 @@ public:
     Q_PROPERTY(Fact* temperature        READ temperature        CONSTANT)
     Q_PROPERTY(Fact* cellCount          READ cellCount          CONSTANT)
     Q_PROPERTY(Fact* instantPower       READ instantPower       CONSTANT)
+    Q_PROPERTY(Fact* timeRemaining      READ timeRemaining      CONSTANT)
+    Q_PROPERTY(Fact* chargeState        READ chargeState        CONSTANT)
 
     Fact* voltage                   (void) { return &_voltageFact; }
     Fact* percentRemaining          (void) { return &_percentRemainingFact; }
@@ -263,7 +265,8 @@ public:
     Fact* temperature               (void) { return &_temperatureFact; }
     Fact* cellCount                 (void) { return &_cellCountFact; }
     Fact* instantPower              (void) { return &_instantPowerFact; }
-
+    Fact* timeRemaining             (void) { return &_timeRemainingFact; }
+    Fact* chargeState               (void) { return &_chargeStateFact; }
 
     static const char* _voltageFactName;
     static const char* _percentRemainingFactName;
@@ -272,6 +275,8 @@ public:
     static const char* _temperatureFactName;
     static const char* _cellCountFactName;
     static const char* _instantPowerFactName;
+    static const char* _timeRemainingFactName;
+    static const char* _chargeStateFactName;
 
     static const char* _settingsGroup;
 
@@ -291,6 +296,8 @@ private:
     Fact            _temperatureFact;
     Fact            _cellCountFact;
     Fact            _instantPowerFact;
+    Fact            _timeRemainingFact;
+    Fact            _chargeStateFact;
 };
 
 class VehicleTemperatureFactGroup : public FactGroup