Help me to choose a power source for the below project:

  • 4x DC Motors (3V~6V DC each with ~170mA),
  • 1x Micro Servo Motor (4.8V~6V),
  • 1x Ultrasonic sensor
  • 1x Bluetooth sensor

It is basically an RC car. The project runs on Arduino UNO and it uses Motor Shield (1.2) to power up those five motors. The motor shield does support external power supply. Shall I go for that, or Arduino can power up the entire system altogether?

  • 1
    First thing I can say, Arduino Uno with external power has a 1A current limit. Besides this, you'd better give some links to the shields and sensors you use then everybody can see the specifications of the devices before answering your question.
    – Sener
    Sep 11 '18 at 12:28

2S LiPo with 5V UBEC is what you want. Hit your favourite RC model seller for those. I use HobbyKing (as the links show).

The capacity choice of the LiPo depends on

  • How much power your motors etc need, and
  • How long you want it to run for

You could also go for 3S or 4S to get more power if your chosen UBEC supports the voltage.

  • Thanks for the comment with links. I am from India and the shipping time to India is horrible from that website. I checked with the local dealer and other websites and it seems there is no luck. Can you suggest a solution with 18650 batteries? like 2x18650 batteries for motor sheild and two for Arduino.? possible?
    – Jithesh Kt
    Sep 12 '18 at 4:24

Many [fake] Arduino UNO boards on the market have an AMS1117 regulator for external power supply from 7.5v to 12v. note that it's a linear regulator and it "wastes" the excess power as heat and compared to the very demanding components you have (about 1 amps) it's obviously not an option. so no. you can't use "External" supply of Arduino to power them all.

it's best to use separate supplies for each board. or you may Use a 5V Battery Kit and connect it to 5V pin on either shields.

  • I believe that the "external power supply" on the motor shield refers to the fact that it can be powered off of an external supply rather than using the regulators on the Arduino board.
    – sa_leinad
    Sep 11 '18 at 14:39
  • @sa_leinad of course it is. many motor applications use a lot of current (and higher voltage) which is far above the capabilities of Arduino's regulator or power tracks. they "must" be powered from an external supply of their own because of interference or heat. but in this case , it should be ok for 5V power rail(bypassed regulator) of Arduino. Sep 11 '18 at 14:52
  • Perhaps rephrase the line: "so no. you can't use "External" supply of Arduino to power them all."
    – sa_leinad
    Sep 11 '18 at 15:01
  • @sa_leinad I assumed the "External supply of Arduino", is an external adapter or battery which goes through regulator of the Arduino UNO board. if the 5V input is considered external, then yes I should rephrase it Sep 11 '18 at 15:09

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