Consider the throttle load for battery voltage calculation

src/modules/commander/commander.cpp

@@ -918,6 +918,11 @@ int commander_thread_main(int argc, char *argv[])
 	struct system_power_s system_power;
 	memset(&system_power, 0, sizeof(system_power));
 
+	/* Subscribe to actuator controls (outputs) */
+	int actuator_controls_sub = orb_subscribe(ORB_ID_VEHICLE_ATTITUDE_CONTROLS);
+	struct actuator_controls_s actuator_controls;
+	memset(&actuator_controls, 0, sizeof(actuator_controls));
+
 	control_status_leds(&status, &armed, true);
 
 	/* now initialized */
@@ -1199,13 +1204,17 @@ int commander_thread_main(int argc, char *argv[])
 
 		if (updated) {
 			orb_copy(ORB_ID(battery_status), battery_sub, &battery);
+			orb_copy(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, actuator_controls_sub, &actuator_controls);
 
 			/* only consider battery voltage if system has been running 2s and battery voltage is valid */
 			if (hrt_absolute_time() > start_time + 2000000 && battery.voltage_filtered_v > 0.0f) {
 				status.battery_voltage = battery.voltage_filtered_v;
 				status.battery_current = battery.current_a;
 				status.condition_battery_voltage_valid = true;
-				status.battery_remaining = battery_remaining_estimate_voltage(battery.voltage_filtered_v, battery.discharged_mah);
+
+				/* get throttle (if armed), as we only care about energy negative throttle also counts */
+				float throttle = (armed.armed) ? fabsf(actuator_controls.control[3]) : 0.0f;
+				status.battery_remaining = battery_remaining_estimate_voltage(battery.voltage_filtered_v, battery.discharged_mah, throttle);
 			}
 		}
 

src/modules/commander/commander_helper.cpp

@@ -281,15 +281,17 @@ void rgbled_set_pattern(rgbled_pattern_t *pattern)
 	}
 }
 
-float battery_remaining_estimate_voltage(float voltage, float discharged)
+float battery_remaining_estimate_voltage(float voltage, float discharged, float throttle_normalized)
 {
 	float ret = 0;
 	static param_t bat_v_empty_h;
 	static param_t bat_v_full_h;
 	static param_t bat_n_cells_h;
 	static param_t bat_capacity_h;
+	static param_t bat_v_load_drop_h;
 	static float bat_v_empty = 3.2f;
 	static float bat_v_full = 4.0f;
+	static float bat_v_load_drop = 0.1f;
 	static int bat_n_cells = 3;
 	static float bat_capacity = -1.0f;
 	static bool initialized = false;
@@ -300,20 +302,22 @@ float battery_remaining_estimate_voltage(float voltage, float discharged)
 		bat_v_full_h = param_find("BAT_V_FULL");
 		bat_n_cells_h = param_find("BAT_N_CELLS");
 		bat_capacity_h = param_find("BAT_CAPACITY");
+		bat_v_load_drop_h = param_find("BAT_V_LOAD_DROP");
 		initialized = true;
 	}
 
 	if (counter % 100 == 0) {
 		param_get(bat_v_empty_h, &bat_v_empty);
 		param_get(bat_v_full_h, &bat_v_full);
+		param_get(bat_v_load_drop_h, &bat_v_load_drop);
 		param_get(bat_n_cells_h, &bat_n_cells);
 		param_get(bat_capacity_h, &bat_capacity);
 	}
 
 	counter++;
 
-	/* remaining charge estimate based on voltage */
-	float remaining_voltage = (voltage - bat_n_cells * bat_v_empty) / (bat_n_cells * (bat_v_full - bat_v_empty));
+	/* remaining charge estimate based on voltage and internal resistance (drop under load) */
+	float remaining_voltage = (voltage - bat_n_cells * (bat_v_empty - (bat_v_load_drop * throttle_normalized)) / (bat_n_cells * (bat_v_full - bat_v_empty));
 
 	if (bat_capacity > 0.0f) {
 		/* if battery capacity is known, use discharged current for estimate, but don't show more than voltage estimate */

src/modules/commander/commander_helper.h

@@ -80,8 +80,9 @@ void rgbled_set_pattern(rgbled_pattern_t *pattern);
  *
  * @param voltage the current battery voltage
  * @param discharged the discharged capacity
+ * @param throttle_normalized the normalized throttle magnitude from 0 to 1. Negative throttle should be converted to this range as well, as it consumes energy.
  * @return the estimated remaining capacity in 0..1
  */
-float battery_remaining_estimate_voltage(float voltage, float discharged);
+float battery_remaining_estimate_voltage(float voltage, float discharged, float throttle_normalized);
 
 #endif /* COMMANDER_HELPER_H_ */

src/modules/commander/commander_params.c

@@ -56,7 +56,7 @@ PARAM_DEFINE_FLOAT(TRIM_YAW, 0.0f);
  *
  * @group Battery Calibration
  */
-PARAM_DEFINE_FLOAT(BAT_V_EMPTY, 3.4f);
+PARAM_DEFINE_FLOAT(BAT_V_EMPTY, 3.3f);
 
 /**
  * Full cell voltage.
@@ -65,7 +65,7 @@ PARAM_DEFINE_FLOAT(BAT_V_EMPTY, 3.4f);
  *
  * @group Battery Calibration
  */
-PARAM_DEFINE_FLOAT(BAT_V_FULL, 3.9f);
+PARAM_DEFINE_FLOAT(BAT_V_FULL, 4.15f);
 
 /**
  * Number of cells.