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I am using Raspberry Pi 3 with Raspbian OS. I will be powering my Pi 3 board from a output of 24V battery. So I will be using a 5V/3A buck converter. I will be connecting my GPS, Pi camera and 4G Dongle to Pi 3. Apart from that gyroscope, accelerometer and temperature sensors are connected to it through GPIO pins.

Is it safe to power Raspberry Pi3 with 5V/3A buck converter?

Suggestions welcome

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    Yes - why would you think otherwise? Aug 10 '18 at 8:28
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Yes, it is perfectly safe.

You lose two protections so take care.

  1. The microUSB socket is keyed so you can't mix up +ve and -ve. Take care when connecting.
  2. The microUSB socket feeds into a polyfuse which limits current to an amp or so. This mitigates against fire risks in the event of some faults. Perhaps add your own fuse.

Alternatively you could wire the power into a microUSB plug so you could keep the above two protections (I power via the expansion header).

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I am using a similar setup with a 12V power rail (from mains with a 12V power supply - not a battery) with a 5V/3A buck converter to power a Pi 1B for more than 3 years now without any issue. Also used this setup with a Pi Zero, Pi 2B and most recently Pi 3B+.

The only suggestion I have is to not power the Pi over the microUSB port but directly over the 5V and GND GPIO pins. Also adjust the output voltage PRIOR to connecting the Pi. You can also install a fuse if you want to feel safe.

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  • Could you explain further, why do you advice to use the GPIOs over the USB port?
    – php_nub_qq
    Mar 18 '20 at 16:15
  • The microUSB-B port is problematic in the sense that the pins have berely contact and provide a big resistance. Thre is a measureable voltage drop on that connector. Also plugs tend to make bad contact. You can get a complete powerloss with some if you push them lightly to either side. USB-C is a better candidate for a reliable power connection. That is why I'd reccomend powering over GPIO. The only drawback is that you don't have a fuse there. So connecting 4 USB harddrives that draw lot of current during startup may cause damage to your pi while over USB port, the fuse just blows up.
    – kwasmich
    Mar 18 '20 at 18:08
  • How does it differ from GPIO pins with regard to contact quality? Without soldering I'd say GPIO connections are far off on the reliability scale. Although this is a RPi3 related question, it's nice to note that about Pi 4 because it comes with an USB-C port, and that happens to be what I have, but had I not known that USB-C is better I would have gone for powering through the GPIOs.
    – php_nub_qq
    Mar 18 '20 at 22:31
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    USB-C is designed to provide up to 100W while microUSB already struggles with 10W. So it was the right decision to switch for the RPi4. GPIO Pins have a larger contact surface and thus a lower resistence than microUSB. Additionally you can use two 5V and two GND pins to make the contact surface even bigger and reduce the voltage drop because of the resistence even more.
    – kwasmich
    Mar 19 '20 at 7:35
  • That's very useful information, probably worth adding to the answer imo.
    – php_nub_qq
    Mar 19 '20 at 7:37
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There is a way to use a buck converter 2 power the Raspberry Pi without bypassing the protections of the USB port. There are numerous videos that online that show this but to give you the cliff notes the pads on the underside of the board can be soldered onto directly and are connected to the USB circuit. Thus bypassing the port but connecting to the circuit providing all the same protections that the USB connection offers without having to deal with the port itself.

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