GrixSilva
Posts: 3
Joined: Thu Aug 15, 2019 11:42 pm

About the power supply...

Fri Aug 16, 2019 12:16 am

Hi!
I recently bought a Raspberry Pi 3B+ and a 5V 2.5A Power Supply (not the official one), but I'm having the Under voltage warning, so i decided to get a new Power supply. My first thought was to buy the official 5.1V 2.5A, but I have searched the internet and some people use higher ampere power supplies.
So my question is if I want to use several peripherals at the same time on my raspberry pi, such as mouse, keyboard, pen drive, controller, usb extenders... will I need a higher ampere power supply to power all these peripherals? Or will the official Power Supply work fine to power all these peripherals?

Sorry if this is a dumb question but i don't know much about voltage and amperage! :P

Thank you for your attention! :)

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Imperf3kt
Posts: 2554
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: About the power supply...

Fri Aug 16, 2019 5:06 am

There is no point using a higher amp power supply without additional ways of accessing that power other than the micro USB connection as the Pi has a polyfuse on it that trips at around 2.6A

Get the official supply, it will power additional peripherals with ease.
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davidcoton
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Joined: Mon Sep 01, 2014 2:37 pm
Location: Cambridge, UK

Re: About the power supply...

Fri Aug 16, 2019 8:57 am

For a full answer, you need to add up the current requirement of the Pi and all the peripherals you want to connect.

As Imperf3kt said, you will also need to pay attention to routing the power so that you don't pull more than 2.5A through the Pi3B+.

Two other things to be aware of with random power supplies:
  1. Many chargers cannot supply the full current at the rated voltage, which will result in low voltage at full load.
  2. Detachable USB cables may have thin power wires (the spec only requires 0.5A), you need to make sure your cable has thick wires (preferably 18AWG) as used on the official PSU.
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GrixSilva
Posts: 3
Joined: Thu Aug 15, 2019 11:42 pm

Re: About the power supply...

Fri Aug 16, 2019 1:35 pm

Thanks for your quick answers!
I think the best option is to buy the official power supply then.

One more thing,
I forgot to mention,
but I would like to add a LED,
a fan and a power button,
the official power supply should work fine, right?

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rpiMike
Posts: 835
Joined: Fri Aug 10, 2012 12:38 pm
Location: Cumbria, UK

Re: About the power supply...

Fri Aug 16, 2019 1:40 pm

Yes, the official power supply will be fine.

Power button on the usb power input is a bad idea - can introduce resistance, better to switch the mains power to the power supply.

GrixSilva
Posts: 3
Joined: Thu Aug 15, 2019 11:42 pm

Re: About the power supply...

Fri Aug 16, 2019 2:03 pm

All right then!
Thank you very much for your help!
I'm going to see what I can do! :D

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