Low battery RTH and flight time

Return to home can be triggered automatically due to low battery. This article describes the parameters considered for triggering RTH and provides recommendations on optimizing the battery consumption.

In optimal conditions, the time to trigger low battery RTH is computed and it should happen after approximately 50 min for WingtraOne GEN II RX1 and after 45 min for WingtraOne GEN I with the RX1RII camera and the PPK module. However, in some situations RTH is automatically triggered earlier. There is no need to manually trigger RTH, the drone will always return to home in time.

During the flight, the amount of battery that the WingtraOne needs to safely return to the home point is estimated. For the battery estimation, the following parameters are taken into account. 

Absolute altitude (above mean sea level) of the home point

Increasing the absolute flight altitude, the density of the air decreases. In those conditions, the motors need more power to generate the thrust required for the flight, so the battery consumption increases. For more details about this parameter and what to do in order to ensure longer flight time, check this article.

Distance to home position

For mapping large areas, the drone flies far away from the home point. As the distance between the drone and the home point increases, the drone needs more battery for a safe return; therefore the RTH will be triggered at a higher level of remaining battery. To delay the low-battery RTH try the following:

• if the terrain allows you, keep the home point closer to the mapping area
• move the home point closer to the remaining part of the area after resuming a mission

For more details on how to map large areas, check this article.

The wind speed and direction

In windy conditions, the drone consumes more energy. Consequently, the battery consumption is increased. More energy is required so that the drone flies safely to home, so RTH is triggered at a higher battery percentage. For recommendations about flying in windy conditions see this article.

Transition height

By increasing the transition height, the drone spends more time hovering up and down and it consumes more energy therefore, to achieve a safe landing the RTH will be triggered earlier. For more details about the transition height, how does it influence the RTH and what to do in order to delay it, check this article.

The biggest impact on battery consumption has the transition height. To extend the flight time, we suggest reducing this parameter, taking always into account all obstacles near the home point. Reducing the time that WingtraOne will spend in hover during takeoff and landing leads to an increase in the total flight time.

RTH mode

The type of RTH mode selected in the Safety parameters may have a slight influence on the flight time. 

Safe RTH, on average, decreases the flight time by 2 to 3 minutes. However, this depends heavily on the terrain and the mission design.

When direct RTH is selected, the minimum RTH height above home safety parameter has a similar impact on the flight time as the transition height. Loitering up and down for a longer period increases the required battery level. The impact of the transition height is clearly stronger than the RTH height. 

Flight time

The following tables present the flight time expectations and the percentage of low-battery RTH at different altitude levels for different environmental conditions.

WingtraOne GEN I

Maximum flight time in optimal conditions (transition altitude: 20m, wind speed < 1m/s, furthest distance from home: 1.2 km, air temperature: 15 °C, RTH mode: direct)

Maximum flight time in default conditions (transition altitude: 50m, wind speed < 3m/s, furthest distance from home: 1.2 km, air temperature: 20 °C, RTH mode: direct)

WingtraOne GEN II

Maximum flight time in optimal conditions (transition altitude: 20m, wind speed < 1m/s, furthest distance from home: 1.2 km, air temperature: 15 °C, RTH mode: direct)