How to Calculate Total Voltage and Current in Arduino Circuit

Projects General Guidance
1

I'm currently on a design project to create a fully automated vehicle. I would like to know how one can calculate the total voltage and current flowing in the circuit provided with the components specifications. I'm quite slow to electrical engineering btw.

List of components:
1x Arduino Mega 2560
1x L293D Motor Shield
1x LSS05 Line detecting sensor
1x Ultrasonic sensor
1x rotary encoder
4x 12V DC motor (0.14A)

I've already got the gist of it where I surely need two external power source and a relay in the circuit later on where a 9V battery (with a switch) to power up the Arduino while 12V battery for the DC motor-relay. I only want to know how much voltage and current I'm dealing with in the future to plan for the necessary resistors or other components to be added in order to prevent thermal failure that could damage my Arduino.

If I missed out on any info, do comment so I can look it up. Thanks in advance.

2

There is no total voltage, every module must be supplied by its specified operating voltage. Each power supply must source at least the total current specified for the connected modules.

3

Hi @DrDiettrich, thank you for your reply. So does that mean I only need a minimum of 12V external power supply to power up all 5 of my 12V DC motor?

4

If you use just one power supply, pick one that can supply at least twice the expected maximum current draw.

The current drawn by the motors will depend on many external circumstances. The figure 0.14 A in the OP cannot be correct. Look up the motor stall current and tell us what that is.

5

would it be correct to just add up all the power for each device ?

1x Arduino Mega 2560
1x L293D Motor Shield ( device consumption and efficiency of sending power to the motors, NOT motor load)
1x LSS05 Line detecting sensor
1x Ultrasonic sensor
1x rotary encoder
4x 12V DC motor (0.14A) motor power x 4.

I would offer that you should calculate the use of each device as if it were at it's maximum rating all the time.

Then calculate power in watts.

Then chose your power supply based on watts.

the motor H-Bridge will consume power for it's own logic and and LED on-board.
the driver will also create heat due to inefficiencis of the device (like any other device)
so the total power used by the L298 is the power used by the device alone, not including the motors.