AP_BatteryMonitor: count mWh spent since powerup

libraries/AP_BattMonitor/AP_BattMonitor.cpp

@@ -196,6 +196,17 @@ bool AP_BattMonitor::healthy(uint8_t instance) const {
     return instance < _num_instances && state[instance].healthy;
 }
 
+/// has_consumed_energy - returns true if battery monitor instance provides consumed energy info
+bool AP_BattMonitor::has_consumed_energy(uint8_t instance) const
+{
+    if (instance < _num_instances && drivers[instance] != nullptr && _params[instance].type() != AP_BattMonitor_Params::BattMonitor_TYPE_NONE) {
+        return drivers[instance]->has_consumed_energy();
+    }
+
+    // not monitoring current
+    return false;
+}
+
 /// has_current - returns true if battery monitor instance provides current info
 bool AP_BattMonitor::has_current(uint8_t instance) const
 {
@@ -247,6 +258,15 @@ float AP_BattMonitor::current_total_mah(uint8_t instance) const {
     }
 }
 
+/// consumed_wh - returns energy consumed since start-up in watt-hours
+float AP_BattMonitor::consumed_wh(uint8_t instance) const {
+    if (instance < _num_instances) {
+        return state[instance].consumed_wh;
+    } else {
+        return 0.0f;
+    }
+}
+
 /// capacity_remaining_pct - returns the % battery capacity remaining (0 ~ 100)
 uint8_t AP_BattMonitor::capacity_remaining_pct(uint8_t instance) const
 {

libraries/AP_BattMonitor/AP_BattMonitor.h

@@ -55,6 +55,7 @@ public:
         float       voltage;            // voltage in volts
         float       current_amps;       // current in amperes
         float       current_total_mah;  // total current draw since start-up
+        float       consumed_wh;        // total energy consumed in Wh since start-up
         uint32_t    last_time_micros;   // time when voltage and current was last read
         uint32_t    low_voltage_start_ms;  // time when voltage dropped below the minimum
         float       temperature;        // battery temperature in celsius
@@ -77,6 +78,10 @@ public:
     bool healthy(uint8_t instance) const;
     bool healthy() const { return healthy(AP_BATT_PRIMARY_INSTANCE); }
 
+    /// has_consumed_energy - returns true if battery monitor instance provides consumed energy info
+    bool has_consumed_energy(uint8_t instance) const;
+    bool has_consumed_energy() const { return has_consumed_energy(AP_BATT_PRIMARY_INSTANCE); }
+
     /// has_current - returns true if battery monitor instance provides current info
     bool has_current(uint8_t instance) const;
     bool has_current() const { return has_current(AP_BATT_PRIMARY_INSTANCE); }
@@ -98,6 +103,10 @@ public:
     float current_total_mah(uint8_t instance) const;
     float current_total_mah() const { return current_total_mah(AP_BATT_PRIMARY_INSTANCE); }
 
+    /// consumed_wh - returns total energy drawn since start-up in watt-hours
+    float consumed_wh(uint8_t instance) const;
+    float consumed_wh() const { return consumed_wh(AP_BATT_PRIMARY_INSTANCE); }
+
     /// capacity_remaining_pct - returns the % battery capacity remaining (0 ~ 100)
     virtual uint8_t capacity_remaining_pct(uint8_t instance) const;
     uint8_t capacity_remaining_pct() const { return capacity_remaining_pct(AP_BATT_PRIMARY_INSTANCE); }

libraries/AP_BattMonitor/AP_BattMonitor_Analog.cpp

@@ -44,7 +44,9 @@ AP_BattMonitor_Analog::read()
         // update total current drawn since startup
         if (_state.last_time_micros != 0 && dt < 2000000.0f) {
             // .0002778 is 1/3600 (conversion to hours)
-            _state.current_total_mah += _state.current_amps * dt * 0.0000002778f;
+            float mah = _state.current_amps * dt * 0.0000002778f;
+            _state.current_total_mah += mah;
+            _state.consumed_wh  += 0.001f * mah * _state.voltage;
         }
 
         // record time

libraries/AP_BattMonitor/AP_BattMonitor_Analog.h

@@ -115,6 +115,9 @@ public:
     /// Read the battery voltage and current.  Should be called at 10hz
     void read();
 
+    /// returns true if battery monitor provides consumed energy info
+    bool has_consumed_energy() const override { return has_current(); }
+
     /// returns true if battery monitor provides current info
     bool has_current() const override;
 

libraries/AP_BattMonitor/AP_BattMonitor_Backend.h

@@ -34,6 +34,9 @@ public:
     // read the latest battery voltage
     virtual void read() = 0;
 
+    /// returns true if battery monitor instance provides consumed energy info
+    virtual bool has_consumed_energy() const { return false; }
+
     /// returns true if battery monitor instance provides current info
     virtual bool has_current() const = 0;