Suggestions for powering RPi, USB WiFi & USB 2.5" HDD ??

[ramb0]

Hi,

What's the best way to power a RPi(b) with USB WiFi & USB 2.5" External HDD connected to the RPi directly?

I may want to power a USB IR Receiver sometime in the future as well.

If i get a single USB Powered Hub, would it be capable of powering all of these?

Any help would be appreciated. Cheers.

[RaTTuS]

A single powered USB hub with a good PSU will do it.
e.g.
http://www.amazon.co.uk/Plugable-Speed- ... B009R921SE

[FTrevorGowen]

Hi,

What's the best way to power a RPi(b) with USB WiFi & USB 2.5" External HDD connected to the RPi directly?

I may want to power a USB IR Receiver sometime in the future as well.

If i get a single USB Powered Hub, would it be capable of powering all of these?

Any help would be appreciated. Cheers.

My personal preference would be to power the external 2.5" USB HDD separately and plug the WiFi dongle into one of the Pi's ports (if you have a "good" 5V 1A PSU - ie. it conforms to its specs! [many don't]). That (excluding the WiFi bit) has been the best approach for the two Linksys NSLU2's I've used, sometimes 24/7 for some years, which run off 5V 2A PSU's. You could use a powered hub, again with a "good" PSU but do not rely on a "Y connector" to provide sufficient power for the HDD. The consensus here seems to be that Belkin hubs are the most reliable in this context (but pricey). FWIW I've investigated the behaviour of a number of lower cost hubs and posted the info. in my web pages at http://www.cpmspectrepi.webspace.virgin ... BHubs.html .
Trev.

[ramb0]

Thanks for feedback guys.

I just purchased a dual USB power supply that outputs 2.1A each USB port, so I'm thinking I might try this first.

Power the RPi (w/ connected USB WiFi) off one USB port, and the 2.5" USB HDD using a 'Y' cable.

Trev, i'm interested in your reasonings behind recommending against powering the 2.5" USB HDD with a Y cable?

[RaTTuS]

When using a Y cable to do a HD [I normallay used a powered HD adaptor and one of my pi's uses that to power itself], I put the cable with the data conenction direct on the RPi and use the other via a powered hub

[FTrevorGowen]

...
Trev, i'm interested in your reasonings behind recommending against powering the 2.5" USB HDD with a Y cable?
...

The Y cable method assumes that the hub can supply up to 500mA per port - one part of the Y is power + data, the other (newer types have a red plug) power only. However, in practice, this only appears to be true for "motherboard hubs" (eg. my Acer netbook). All of the "powered" USB hubs I've checked appear to have their ports connected in parallel and hence, apart from a slightly reduced cable resistance, using two ports gains nothing (and you lose the use of that port for anything else). Many "older" 2.5" drives require transient currents up to 1A (on motor spin-up or head seek) and, to my cost, I've ended up with three drives becoming unusable due to MBR corruption (could not be re-formatted) after trying to use them on a powered hub. If powered via their separate power socket (where it existed) I had no problems. Additionally, any PSU used with a powered hub needs to be able to supply the total maximum current for all ports if required to perform at full spec. (ie. for a 4-port hub - 2A). Apart from losing the drives mentioned above, the main reason I investigated deeper was the inability of such hubs to work with a "Y-connected" CD/DVD drive originally supplied with a Median laptop some years ago, and which otherwise worked with three newer netbooks. To date I've only managed to get that to work with a Hama hub powered from a 5V 2A supply. Hope this clarifies matters somewhat.
Trev.