Common Power Module

../_images/3DR-current-sensor-top.jpg

Many autopilots can be purchased with an analog power module that provides a stable power supply to the autopilot and also supports measuring the battery voltage and current consumption.

Specifications

Below are typical limits but it may be best to confirm directly with the vendor:

  • Maximum input voltage of 18V (4S lipo)
  • Maximum of 90 Amps (but only capable of measuring up to 60 Amps)
  • Provides 5.37V and 2.25Amp power supply to the autopilot

Warning

The Power Module provides enough power for the autopilot, receiver, and a few low powered peripherals (lidar, telemetry) but does not have enough power for servos or high current devices like FPV transmitters or the RFD900 radios. More information on powering the Pixhawk can be found here

Connecting to the autopilot

The 6 pin cable from the power module plugs into the POWER port of the autopilot

../_images/powermodule-analog-pixhawk.png

The battery is connected to the power module’s male connector. The ESC or Power Distribution Board should be connected to the power module’s female connector.

Configuration

Most ground stations provide a battery monitor interface but the parameters can also be set manually:

  • BATT_MONITOR = 3 to measure only voltage or 4 to measure both voltage and current (you will need to reboot the board after changing this)
  • BATT_VOLT_PIN = 2. The autopilot pin connected to the power module’s voltage pin
  • BATT_VOLT_MULT converts the analog voltage received from the power module’s voltage pin to the battery’s voltage
  • BATT_CURR_PIN = 3. The autopilot pin connected to the power module’s current pin
  • BATT_AMP_PERVLT converts the analog voltage received from the power module’s current pin to the battery’s current
  • BATT_AMP_OFFSET voltage offset received from the power module’s current pin when ther is no current being pulled from the battery

Instructions for setup and calibration using the Mission Planner can be found here A Blog post with instructions for set-up using QGC can be found here

Dual Battery Monitoring

If the autopilot has additional analog-to-digital pins available, a second battery can be monitored by setting up the BATT2_ parameters. The values below allow reading a second battery’s voltage and current using The Cube’s POWER2 port.

The BATT2_VOLT_MULT and BATT2_AMP_PERVLT should also be set by comparing the reported values vs values collected using a hand held voltage meter

../_images/powermodule-dual-monitoring.png

Failsafe

Instructions for battery failsafe can be found here