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So here it goes,after looking out hundreds of pages regarding powering of Raspberry Pi 3B+ still some hesitations here.

I have totally read this out very detailed & nicely written answer by Milliways & official Raspberry Pi documentation along with many Reddit post. I came to know that i can use any power adapter of any output current rating provided that it ( adapter) capable delivering constant 5 Volts(±0.25V) supply.

As Raspberry Pi itself will draw only amount of current it needs from adapter as long as voltage provided to board is constant as standard input rating.

So my concern is can i go for power adapter which can deliver 3.4 Ampere or Qualcomm QC 3.0 capable( as it can deliver 5V-3A or 9V-1.6V or 12V-1.2A) as Raspberry Pi capable of handling current value.

Pritish Pandit
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  • well, qc3 or 3a should be ok. – tlfong01 Sep 10 '19 at 13:03
  • I'm not sure what you want to know. The Pi3B requires a 5V power supply capable of providing 2.5 amps or so. Does the PSU you have chosen meet that spec? Why ask us? – joan Sep 10 '19 at 13:21
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    The only thing matters is that the Voltage remains the same and that the Amps are at least what the device needs, if you supply more voltage you can burn the device, if you supply too much amps the device will only used what's necessary. – Yaron Sep 10 '19 at 14:06
  • @joan The psu(adaptor) i have chosen defintely meets Voltage requirements but Current rating is higher than requirements of RPi 3B+.So the question is, will the extra current delivered by power adapter damage my Pi board ?? – Pritish Pandit Sep 10 '19 at 15:16
  • Related if not dupe https://raspberrypi.stackexchange.com/q/41514/19949 – Ghanima Sep 17 '19 at 00:13

1 Answers1

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The short answer to your question is no, as long as it outputs 5V the worst it can do is not supply enough current (see footnote).

Raspberry Pi capable of handling current value.

That's not how electricity works, at least in a power supply context. Devices have a minimum current rating, and supplies have a maximum rating. The supply only sources the current that the device sinks, ie., if the device only needs 2A but the supply has a maximum of 4A, the supply is fine -- it can deliver 2A. Note that the current draw of an electronic device like the Pi can fluctuate substantially depending on the internal needs of its components; it may draw < 1A when idle with no powered peripherals.1

So what's important is that the device's requirements are less than or equal to the maximum current output of the supply. Not that this logic does not apply to voltage, which must be a close match, and unlike current, should not substantially fluctuate.

  1. This is significant in that power supplies that are really intended only for recharging things may not be designed to handle this fluctuating draw, in which case the Pi may brown out under load. This may cause SD card corruption, but it should not damage the Pi.
goldilocks
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  • Thanks @Goldilocks for explaining it out. Continuing to your answer,does it mean that If, varying current demand by Pi board is not satisfied by adapter ,it might reflect in curpting of SD card or browining out of board ? – Pritish Pandit Sep 10 '19 at 15:33
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    By "brown out" I mean that if the supply cannot deliver enough current at 5V, what happens is the voltage will drop, which may cause the board to effectively shut down momentarily, then the current draw will stop and the voltage will go back, starting it running again. Which is more or less the same as flicking the power on and off -- it won't damage the board, but anytime you do an "unclean shutdown" (ie., without properly shutting down the OS), you risk filesystem corruption. I promise you will end up pulling the plug anyway at some point, so don't be scared, just try to avoid it. – goldilocks Sep 10 '19 at 16:00
  • The problem is something that applies more to powerbanks than actual plug into the wall chargers. You will get a clue in that the red led will flicker and if you are using a display a yellow lightning bolt will appear in a corner of the screen. – goldilocks Sep 10 '19 at 16:02
  • If your are happy with this answer, please tick the big question mark on the left side. – goldilocks Sep 11 '19 at 13:43
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    @goldilocks it's not a question mark, now is it? – Ghanima Sep 17 '19 at 00:10