To start, I am a software guy, so I am not too clued up on the electronics side of things. My question is: I have a number of Arduino shields and would like to power them with a portable power source, and therefore would like some advice on what to use without frying any electronics.

This is a list of the current equipment that will require power:

The shields will be stacked on top of each other.

  • Further links as I could not post them in the main question: Arduino Mega, SIM900
    – Calco
    Commented Aug 10, 2016 at 8:27

2 Answers 2


Your stack will need quite a lot of current - most probably more than the Arduino can supply itself.

You will need to provide your own regulated 5V supply - either from a USB port (convenient if you are by a computer) - as long as it can supply more than 500mA of current (you need a Charging Downstream Port CDP for that) or from some external regulated 5V power supply, such as a mobile phone charger.

That 5V supply should be connected direct to the 5V pin of the Arduino's power header.

One thing to note: the headers themselves are only rated for up to 1A. If you need more than 1A throughout the entire stack it could be worth connecting the 5V power supply direct to the 5V pins of ALL the shields in the stack. Also do the same with the GND pins to the negative of the power supply. That way the high current doesn't need to flow through the pins themselves.

  • Yes.. Mjanco is right. Connect supply to 5V pin Commented Aug 10, 2016 at 13:40

All the shields are 5v compatible. So no need to worry about 3.3v.

But there may be a chance of insufficient current if you use a battery to the power-jack of arduino mega (due to the internal voltage regulator). I'd suggest you cut a USB cable and solder the +5(red color) wire to VIN on the mega and ground(black wire) to GND pin. And use a 'power bank', which is used for mobile phones.

  • So I can simply attach a USB's red to the VIN and black to the GND, and then using any mobile phone power bank will provide enough current and voltage for all of the shields? Wow, that seems super straightforward!
    – Calco
    Commented Aug 10, 2016 at 9:50
  • Yea.. please try this. They can deliver around 2A which will be sufficient. And interface on shield at a time. This will help yiu to resolve pin conflicts (same pins ued for multiple sheilds) good luck
    – Sanu - Open Maker
    Commented Aug 10, 2016 at 9:57
  • *one shield at a time
    – Sanu - Open Maker
    Commented Aug 10, 2016 at 9:58
  • What do you mean interface one shield at a time?
    – Calco
    Commented Aug 10, 2016 at 9:59
  • 1
    DON'T CONNECT A 5V SUPPLY TO VIN - Vin goes through the 5V regulator - you will end up with about 4V instead of 5V. Instead connect the 5V supply direct to the 5V pin of the Arduino.
    – Majenko
    Commented Aug 10, 2016 at 13:21

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