Pete-Bot – Measuring Power Consumption
Written by Melwin Pakpahan (Mission, System, Test)
Description:
The power consumption of the 3DoT board will be measured as follows. A RCR123A battery will be connected in series with a test resistor and the 3DoT board. Two versions of the 3DoT board will be tested and compared. The test resistor is chosen to be 1 ohm, and the current draw is to be determined. When the power source is switched on, the voltage across the resistor is used to calculate the current going through the circuit using Ohm’s law.
Equation 1 – Ohm’s Law
Equation 2 – Variation of Ohm’s Law
Considerations
- The battery is fully charged before any test is conducted.
- A test code (“Motor_Operation_Test”) has been verified and uploaded to the 3DoT Board.
- The motors continulously run during the test.
Cases
There are three cases of testing for the power consumption.
- Case One – Testing power consumption with no motors
- Case Two – Testing power consumption with one motor running
- Case Three – Testing power consumption with two motors running
Case One
Figure One shows the circuit diagram for this first test:
Figure One – Circuit diagram for testing power consumption (general)
Case Two
A GM6 motor is connected and running as shown in Figure Two.
Figure Two – Circuit diagram for testing power consumption with one GM6 motor attached
Case Three
Two GM6 motors are connected and running as shown in Figure Three.
Figure Three – Circuit diagram for testing power consumption with two GM6 motors attached
Constraint
Up until this point, Bluetooth communication has not been established yet. The procedures above will be repeated once communication is established.
Results
Figure Four shows a measurement of the resistor. Although, the specified value is 1 ohm, the actual value is 1.1 ohm. This measured value is desired since it provides a more accurate measurement of the current values. Figure Five shows the test run of the 3DoT board Rev 4.46 without actuators and without Bluetooth pairing. Table 1 shows the results of each test case.
Figure Four
Figure Five
Table of Results
Table One – Table summarizing results