I've got this mobile charger and I'm wondering if I can use it to power my pi4. If so, what should I look out for when buying a usb2-usbC adaptor? portable charger

  • why have you not tried it before you posted here?
    – jsotola
    Jan 22, 2020 at 1:46
  • Please post the spec of this charger. Input 5V 1.5A Output 5V 2.1A doesn't make sense physically. Feb 2, 2020 at 19:44

3 Answers 3


I searched and found this link:

I think it's your charger/power bank. As you can see on the description on the device and the link, the output is 2.1A (2.1 Amper) at 5V (5 Volt DC).

On the other hand, "The Foundation's" published figures for power consumption across all models of Raspberry Pi shows a figure for RPi 4B which is 3.0A at 5V.

All in all, your charger/power bank may turn on the Raspberry Pi 4B but it's not safe, at all.


As stated in the Raspberry Pi Model B specifications found here, the "minimum*" current for the Raspberry Pi 4 via the USB-C connector and GPIO headers is 3A. (* being a "good quality 2.5A power supply can be used if downstream USB peripherals consume less than 500mA in total.")

Also, in the answer to this question, the user states that while 3A is "recommended", 2.5A is the "minimum".

These values are well above the 2.1A output stated on the charger that you have shown us. Most likely, the charger will not work, and the Pi will either lose power the second after it starts booting, or lose power under intense loads on the CPU. Also, from personal experience with my Pi3 B+, I found a 2.1A charger doesn't work at all.

  • Nowhere does the documentation state a minimum. The Foundation has recommendations for various models which range from 700mA to 3.0A. The Pi4 will quite happily run on a 1A supply, although peripherals may require more.
    – Milliways
    Jan 22, 2020 at 3:29
  • While I can agree that the current given isn't exactly a minimum, I was merely quoting the (official) source that I linked, which used the words "minimum 3A*". I've edited the answer to help clarify that.
    – Synchronic
    Jan 25, 2020 at 2:35

In general chargers do a poor job of providing a well regulated 5V output - you need a Power Supply

No one can say what your unidentified charger does, but if it has a USB2 output it will probably not work.

A USB-C power unit MAY work, but even this varies.

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