Pi3B External HDD Power Supply

[Thiago_Rangel7]

I'm buying the components I need to setup a home NAS / Media Centre / Torrent Box running 24/7. So far, here is what I've got:
- 1 Raspberry Pi 3 Model B
- 1 SanDisk 16GB MicroSD Class 10
- 1 Case with cooler
- 1 Seagate Backup Plus Slim Portable Drive 1TB

How is the best way to power it all? I was wondering if it would work fine using a 5V 2,2A power supply; or should I get a powered USB HUB?

Thanks.

[fruitoftheloom]

I'm buying the components I need to setup a home NAS / Media Centre / Torrent Box running 24/7. So far, here is what I've got:
- 1 Raspberry Pi 3 Model B
- 1 SanDisk 16GB MicroSD Class 10
- 1 Case with cooler
- 1 Seagate Backup Plus Slim Portable Drive 1TB

How is the best way to power it all? I was wondering if it would work fine using a 5V 2,2A power supply; or should I get a powered USB HUB?

Thanks.

Welcome, the RPi 3B offers 1200mA shared between the 4 USB Ports:

https://www.raspberrypi.org/help/faqs/#powerReqs

The RPF recommend a 5.1V 2.5A PSU:

https://www.raspberrypi.org/products/un ... er-supply/

[peterlite]

The official 2.5 amp power supply will run that config. You may run out of power if you add a second disk or other high power device. At that stage, you can add a powered hub. For a NAS with two disks, I used a 4 amp USB3 hub.

There are lots of posts pointing out the problems with powered hubs, voltage drops due to weak power supplies or thin wires. USB hubs vary widely in their success. Most USB devices accept a lower voltage than what the Pi can use. Most USB hubs start with 5 volt then drop under load. The official power supply starts at something like 5.3 volts.

[Thiago_Rangel7]

The official 2.5 amp power supply will run that config. You may run out of power if you add a second disk or other high power device. At that stage, you can add a powered hub. For a NAS with two disks, I used a 4 amp USB3 hub.

There are lots of posts pointing out the problems with powered hubs, voltage drops due to weak power supplies or thin wires. USB hubs vary widely in their success. Most USB devices accept a lower voltage than what the Pi can use. Most USB hubs start with 5 volt then drop under load. The official power supply starts at something like 5.3 volts.

Do you think it would work with a 5V 2.2A power supply? I can't buy the official one, its hard to find/buy it where I live.

[Thiago_Rangel7]

I'm buying the components I need to setup a home NAS / Media Centre / Torrent Box running 24/7. So far, here is what I've got:
- 1 Raspberry Pi 3 Model B
- 1 SanDisk 16GB MicroSD Class 10
- 1 Case with cooler
- 1 Seagate Backup Plus Slim Portable Drive 1TB

How is the best way to power it all? I was wondering if it would work fine using a 5V 2,2A power supply; or should I get a powered USB HUB?

Thanks.

Welcome, the RPi 3B offers 1200mA shared between the 4 USB Ports:

https://www.raspberrypi.org/help/faqs/#powerReqs

The RPF recommend a 5.1V 2.5A PSU:

https://www.raspberrypi.org/products/un ... er-supply/

OK, it offers 1200mA shared between 4 USB Ports, but how much does the external HDD need to operate properly?

[fruitoftheloom]

I'm buying the components I need to setup a home NAS / Media Centre / Torrent Box running 24/7. So far, here is what I've got:
- 1 Raspberry Pi 3 Model B
- 1 SanDisk 16GB MicroSD Class 10
- 1 Case with cooler
- 1 Seagate Backup Plus Slim Portable Drive 1TB

How is the best way to power it all? I was wondering if it would work fine using a 5V 2,2A power supply; or should I get a powered USB HUB?

Thanks.

Welcome, the RPi 3B offers 1200mA shared between the 4 USB Ports:

https://www.raspberrypi.org/help/faqs/#powerReqs

The RPF recommend a 5.1V 2.5A PSU:

https://www.raspberrypi.org/products/un ... er-supply/

OK, it offers 1200mA shared between 4 USB Ports, but how much does the external HDD need to operate properly?

The manufacturer should provide the information of the load under drive spin up......

[tweak42]

OK, it offers 1200mA shared between 4 USB Ports, but how much does the external HDD need to operate properly?

I ran some quick power up tests using a USB power meter. With a cheap usb 2.0 to sata adapter and mechanical 2.5" 40GB and 500GB drives, both spiked up to around 800mA at spin up then settled at 300mA. Using the same drives in a cheap usb 3.0 enclosure yielded 1000mA spin up and about 400mA idle. This were using quality 1 foot usb cables.

A 2.5" Seagate Backup drive probably falls somewhere between there for amp draw. A quality 2A power supply should work, but it's also important to use short thick USB cable for power.

[HawaiianPi]

Do you think it would work with a 5V 2.2A power supply? I can't buy the official one, its hard to find/buy it where I live.

It really depends on the power supply. There's no way to know without testing it.

The problem is that most 5V USB power supplies are phone or tablet chargers, and battery charging is far less sensitive to voltage fluctuations than a computer will be. As a result, some phone/tablet chargers have poor voltage regulation. I have tested 5V/2.4A supplies that dipped down to 4.5V at only a 1A load. That will still charge a phone or tablet, but it will not run a Raspberry Pi3.

Another potential problem is that many USB 2.0 cables are only designed to deliver 500mA, which is the USB 2.0 power specification, so they have thin wires with too much resistance for the kind of power a Pi3 will draw. This is especially true for Micro-USB cables. I posted a thread about the best Micro USB cables I have tested that you might want to take a look at.

Personally, I use a RAVPower RP-PC002W tablet/phone charger which outputs 5.3V/2.4A from its "iSmart" port (tested 5.2V at over 2A load). 5.3V is a little higher than the USB 2.0 specification of +/- 5% (4.75-5.25V), but it hasn't been a problem for me (even a high quality Micro-USB cable probably drops the voltage at least 0.05V, so power at the Pi end is likely within spec).

To test power/voltage there are inexpensive USB digital multimeters available on Amazon and ebay. I have posted links to a couple below. While I wouldn't call them accurate enough for precision measurements, they are good enough for general testing.

Leezo USB 2.0 Multi Tester
DROK USB 2.0 Digital Multimeter

A good 5V, 2A+ power supply should be enough to run a Pi3 under all but the most heavily loaded conditions, so if your 2.2A unit has good voltage regulation, AND you are using a good quality Micro-USB cable, it should work.

If you are planning on running more than one USB powered hard drive, then you will need some way to power the drives independent of the Pi3. My RAVPower PSU is the only one I have tested that was able to boot my Pi3 with two portable hard drives connected, but even though the drives spun up and mounted correctly, I could only use one at a time. When I assemble a portable drive myself I always buy enclosures with external power as an option, so if I need to I can power the drive separately. Unfortunately many pre-assembled portable hard drives do not have that as an option. They usually come with a 3 headed cable that allows you to draw power from two USB ports, but that won't help on a Raspberry Pi3, which has no per-port power restrictions (which is good), but the total power available to its 4 USB 2.0 ports is significantly less than the USB 2.0 power specification (which is not so good).

[jogl]

Unless you need more usb ports I would just power the HD separately. Simpler, fewer wires, and less cost.