Configure a Current-Voltage sensor

Basic voltage sensor

A basic voltage divider can be used, two resistors connected between ground and + from battery.

For a 4S battery (16.8Volts) the following values can be used:

R1: 2,2KOhms and R2: 10KOhms

With Vbattery = 16.8V,  Vout = (16.8 * 2.2) / (10 + 2.2) =  3,03V

See also http://en.wikipedia.org/wiki/Voltage_divider

Disable TIME alarm

If you use this simple voltage sensor alone, you need to disable the TIME alarm.

This alarm is based on energy consumed that cannot be computed without current sensor.

Go to UavoBrowser > FlightBatterySettings and set the Capacity to 0

The first thing to do is to configure the hardware settings:

1 - Connect the board to your computer and got to the System tab in your GCS

2 - Browse the first part (Settings) and find the HwSettings UAVObject

3 - Enable the Battery module  : OptionalModules > Battery > Enable

4 - Set the analog input pins for voltage and current :

• ADCRouting > adc0 > BatteryCurrent
• ADCRouting > adc1 > BatteryVoltage

5 - Save changes, click Upload button :

6 - Reboot your board: disconnect all power sources and reconnect to your computer.

Here is the adc mapping for various boards:

FlexiIO refers to the receiver port

Now connect the battery to the battery sensor, if changes are done and battery module enabled you can see the display on PFD:

But values displayed are not accurate, we need to calibrate sensor!

To configure the battery monitor, you need to calculate the SensorCalibration values.

For example, the documentation for Attopilot current sensor specifies the following information for each sensor type:

In order to use 50V/90A you'll have to do the following:

Convert everything to Volt, so Volt/Volt and Volt/Amp:

63.69mV/V / 1000 = 0.06369 V/V

36.60mV/A / 1000 = 0.0366 V/A

Then calculate the values to insert in Voltage and Current Factors:

VoltageFactor = 1 / 0.06369 = 15.701

CurrentFactor = 1 / 0.0366 = 27.322

Those factors are start values that can be adjusted later from readings, generally sensor's sensitivity are not so accurate.

1 - Connect the board to your computer and got to the System tab in your GCS

2 - Browse the first part (Settings) and find the FlightBatterySettings UAVObject

3 - Set the VoltageFactor and CurrentFactor as in the previous section.

4 - Set the cell Capacity if you want a warning to be issued when there are less than 2 minutes of flight time available; otherwise, set to 0.

5 - Set NbCells with the number of cells in series (2 for 2S, 3 for 3S, 3 for 3S2P)

6 - Set the Warning and Alarm thresholds if you would like a warning or critical alarm to be issued when going under the values that you specify.

7 - Save changes, click Upload button :