Raspberry Pi Forums

Hi all,

I have searched online quite a bit but not really found an answer that has proved sufficient.

So I bought a Raspberry pi B+, with plans to add an 3.5" Western Digital Red (as a backup solution).
I have read that one should by the model B+ so one can unlock the extra power needed for external hard drives.

However isn't this only if the HDD is a 2.5" (since they usually only require 500 mA to run)? and therefore one would have a setup as follows:
Power adapter 2.0A 5V ----> Raspberry Pi B+ ------> USB to SATA cable ----> 2.5" HDD

But since I have a 3.5" 500 mA (USB 2.0 max power output) will not be sufficient ergo a setup like this is needed:
Power adapter 1A 5V ----> RaspBeryy Pi (standard model) ----> USB to SATA cable ----> 3.5" HDD <------ new Power adapter 1.2-ishA with 5V

Since the Pi no longer can run the HDD a dedicated power source and a regular PI might be enough?

Or am I wrong? Are there better solutions for my use of 3.5" HDD?

That disk might be too power hungry for a Pi, whether it is a B or B+.

You will have to give it a separate powersupply. And then you can use a B or a B+
B+ advantage here will be the extra USB ports.

A 500 mA power supply for a RPi is too weak anyway.

hansotten wrote:That disk might be too power hungry for a Pi, whether it is a B or B+.

You will have to give it a separate powersupply. And then you can use a B or a B+
B+ advantage here will be the extra USB ports.

A 500 mA power supply for a RPi is too weak anyway.

That is correct the WD Red has a peak of 5.4W so I would need 1.2A or more to support it.

Thanks then I know.

Don't 3.5" SATA drives require 5V AND 12VDC?
My cheap USB to SATA adapter has a dual voltage 12V & 5V power supply 'brick'.

klricks wrote:Don't 3.5" SATA drives require 5V AND 12VDC?
My cheap USB to SATA adapter has a dual voltage 12V & 5V power supply 'brick'.

Every one I've seen does. 12V for the motor, 5V for the logic. Sometimes the External power brick is 12Volts and the electronics inside the case provide the 5V from it.