Maximum Current Raspi 4B

[wsperat]

Hello everybody!
I am very new to the raspberry pi world. My family got me a Raspberry Pi 4 Model B, though it came without a power supply; due to shipping policies in my country during the pandemic, getting an official power supply is out of the question, so I'm looking for alternatives. I found both a 5V 2.5A power supply, and a 5V 4.2A power supply. According to my model's specifications, it needs a 3A one, so I'm not sure if I should keep looking, or if one of these will do.
My pretended use for the device is to be used in a NAS project, so it will have a HDD attached constantly.
Thanks in advance!

[davidcoton]

If you need a full 1.2A supply from USB (and/or GPIO) for HDD and other peripherals, the 2.5A supply will not be enough.
The 4.2A supply should be plenty in any case.
As long as the supply capacity is equal to or greater than what you are actually using, there should be no problem.
The big "gotcha" is that some USB "chargers" cannot maintain the correct voltage at full load. "Power supplies" should be better in this regard.
The other thing to remember is that the cable needs a USB-C plug for the Pi4B. The wires must also be thick enough to carry 3A without undue voltage loss. The cable may be marked something like "28AWG/1P +20AWG/2C". The third number (20 in my example) defines the power conductor size and should be no higher than 20. 18 is better.

[hippy]

I found both a 5V 2.5A power supply, and a 5V 4.2A power supply. According to my model's specifications, it needs a 3A one, so I'm not sure if I should keep looking, or if one of these will do.

The 4.2A supply supplies more than the 3A maximum a Pi 4B will use so that should be fine. And that may allow splitting the supply to externally supply your HDD rather than powering it through USB if that proves problematic.

The 2.5A supply will likely be enough if you don't draw much current out of the USB ports. You may need to separately power your HDD.

[fruitoftheloom]

Hello everybody!
I am very new to the raspberry pi world. My family got me a Raspberry Pi 4 Model B, though it came without a power supply; due to shipping policies in my country during the pandemic, getting an official power supply is out of the question, so I'm looking for alternatives. I found both a 5V 2.5A power supply, and a 5V 4.2A power supply. According to my model's specifications, it needs a 3A one, so I'm not sure if I should keep looking, or if one of these will do.
My pretended use for the device is to be used in a NAS project, so it will have a HDD attached constantly.
Thanks in advance!

Is it a Power Supply or a Phone Charger or a Power Delivery Charger ??