I have just completed my first Hexacopter build and I am preparing for the maiden flight. Since I am new to the ArduPilot ecosystem, I am trying to follow the documentation step-by-step.
I have completed the “First Time Setup” configuration. Now, I am working on the “Setting the Aircraft Up for Tuning” guide. I would like to use the “Initial Parameter Set” feature in Mission Planner to establish a solid baseline for the PIDs.
However, the tool requires a calibrated Battery Monitor (specifically Current/Amps). I reviewed the documentation for Current Calibration (the method involving reversing propellers and rotating them one position around the copter). To be honest, as this is my first large build, I am concerned about the safety risks of running the motors at high throttle on the bench with reversed props.
My Setup:
Frame: Hexacopter
Weight: ~2.5 kg (AUW)
Props: 10x4.5
Flight Controller: Pixhawk Cube Black
Power Module: The standard Power Brick Mini (included in the Cube Black kit)
My Plan & Goal:
I plan to perform my maiden flight in Stabilize mode.
I will not be using Battery Failsafe actions for now.
My main goal with this calibration is to prevent PID performance loss as the battery drains (maintaining consistent hover/flight characteristics).
My Questions:
1. About the Bench Calibration Process: I am concerned about the safety of the bench calibration method. Could you please explain the exact process for the “reverse prop” technique?
Is simply flipping the propeller upside down sufficient?
Or do I also need to swap the propellers between motors (changing the rotation direction relative to the prop) to ensure the thrust is directed downwards (pushing the drone into the ground)?
I want to make sure I don’t accidentally create a situation where the prop nut loosens or the drone becomes unstable on the bench.
2. Is Bench Calibration Mandatory? Considering I am using the standard Cube Black Power Brick and my goal is just PID consistency; is it acceptable to use the default parameters for this module, fly cautiously, and then calibrate the current sensor using the “Charger mAh vs Logged mAh” method afterwards?
IMHO the cube power bricks are accurate enough to get you started. Then tweaking using the charger vs logged works really well to get things dialed in.
Hi again everyone,
First of all, thank you very much for your answers. Based on your advice, I will proceed with using the default parameters instead of doing a risky bench calibration.
However, I encountered a specific situation while setting this up.
I am using the POWER 2 port on the Cube Black for my power module. In Mission Planner > Battery Monitor, I manually selected the pins to match the POWER 2 port:
Volt Pin:Pixhawk2_PM2/CubeOrange
Current Pin:Pixhawk2_PM2
The Issue: As you can see in the attached screenshot, after selecting the PM2 pins manually, the “Amperes per volt” field remains completely empty. It did not auto-populate with a default value.
My Question: Is this normal behavior when using power 2 port? Since I am using the standard Cube Black Power Brick, is it safe for me to manually enter 18.0 or different constant value into this field and save it? If so what should the constant value be?
Thank you for your quick reply.
I couldn’t find any information indicating that the power2 connector can’t measure current.
Since the “Amps per volt” section is blank, I’m thinking of selecting Monitor > Analog Voltage Only. Would this work, or would it cause problems?
Thank you for your reply. I checked the volt pin and current pins in the image I shared against those in your list, and they match. The problem is that the “Amps per Volt” section is not filled in.
I don’t have a Cube Black but entering the correct pin numbers for a Cube Black in the Full Parameter list produces this configuration in the battery monitor screens. It populates after setting the parameters manually which is the best way to do it.
Then charge your battery fully and do a flight consuming atleast 50% of your battery. Note the used mAh reading from arducopter. Then recharge your battery and note how much capacity the charger put back in. Now change your amps/volt value as
New value = Current Value * (Charged capacity / Estimated used capacity)
Now the value should be pretty close to the real value. If not, repeat the above steps until you get it close enough.
I checked the pins in the full parameter list and confirmed they were correct for the Power 2 port. However, the “Amps per Volt” field remained blank.
To resolve this completely, I decided to switch my connection from the POWER 2 port to the POWER 1 port on the Cube. Now, Mission Planner is populating the default values automatically.
However, I am unsure which “Sensor” option I should select from the dropdown list for the correct parameters. I am using the standard Power Brick Mini (included in the Cube Black kit), as shown in the attached photo.
Should I select “Cube HV Power Module”, “3DR Power Module”, or something else?
Thanks again for your help.
Hello again,
I verified my physical wiring to ensure there is no bypass: Battery → Power Module → PDB → ESCs. (The current flows through the module).
Current Status:
Pins: Configured for Power 1 (Volt Pin: 2, Current Pin: 3).
Idle Reading: When disarmed (USB + Battery), I see a realistic fluctuating current of 0.1A - 0.3A (Avionics draw).
The Issue: When I arm and spin the motors up to ~50% throttle (without propellers), the current reading remains near 0A / Idle levels. It does not show a significant increase.
My Questions:
Is it normal for the current reading not to reflect the motor spin during a no-load (prop-less) test, or does this indicate wrong Amps Per Volt value or something else like hardware issue etc.?
Since the difference between multimeter reading and the sensor reading was less than 0.2 volts, I didn’t change the voltage value. (That’s what it says in the Arducopter documentation.)
