External USB hard drive connected SIMULTANEOUSLY to laptop and USB powered hub: safe? works?

Hello,

I have a external 2.5" hard drive (in enclosure with USB port ). It has a "Y" USB cable (to connect to 2 usb ports in my laptop, if more current is needed).
Can I connect the "Y" cable to the laptop AND to a powered (external power adapter) USB hub? The intention would be to get from the usb hub any extra power the hard drive may need. Is this safe? Does it make sense? The hub is not connected to the laptop - will it work properly?

Thanks

 

So let me make sure I am understanding this correctly.

You have a hard drive that needs two USB ports to work. You want to plug one directly into the laptop and another one into a Externally powered USB hub which will then be connected into the laptop?

I think that will work if that is what you plan on doing. Just be careful with those USB hubs because I had one that didn't have an external power source and it killed all my laptop's USB ports.
Tim

 

Yes that setup will be fine and provide plenty of power for your external drive.

I don't even bother with the other end of Y cable but that's just me. I don't advise people to do the same. Hard drives uses the most power during initial hard disk spin up. Notebook HD don't consume too much power during operation and idle (0-3watts).

 

One directly into the laptop, and the other into the externally powered hub, BUT the hub is not connected into the laptop. The idea is to use the hub only to power the HDD....and (why not) power any other device that gets powered through a usb port (like cooling pad..)

 

Thanks for your comment, but I do not understand what you say regarding the other end of the Y cable.
One end goes to the laptop, the other goes to the externally powered hub. Please explain.

Regarding 0-3 watts, my understanding is that the usb port can supply 2.5 watts.... probably not enough for certain drives and/or under certain conditions.

 

I was generous with the 3w for seeking/idle but during spin up it can consume about 1w more. Tomshardware have a good chart showing the power consumptions of many 2.5" HD.

http://tomshardware.co.uk/storage/charts25.html?modelx=33&model1=425&model2=414&chart=156
http://tomshardware.co.uk/storage/charts25.html?modelx=33&model1=425&model2=414&chart=157

What I mean is that I plug one end into the laptop and the other end of the Y cable no where. I've been using this for years like that but I also make sure the specific model of hard drive don't consume too much power. I only use 4200rpm/5400rpm drives. 7200rpm drives won't have any improvements anyway because usb2 bottlenecks the performance. Practical, not theorectical max transfer rates over USB2 is about 30MB/s or 240Mbits/s.

To be safe I would advise using both ends of the Y splitter. I also advise people to plug in the "usb power only" first (the lead that branches out of the Y splitter) then followed by the "usb data+power". This is because as mentioned before it consumes most power during initialisation of the HD.

 

I haven't ever had a 2.5" drive that required more power. Have you tried it without connecting both usb ends? I am almost certain it will work.

 

Great links, thanks Looks like I accidentally bought the lower-power 160GB drive. I was trying to figure out what the difference between the Seagate and Hitachi was, and was tempted to go with the Seagate because of the longer warranty, but ended up with the Hitachi.

 

Nominally mine have two cables, one connects for "power" the other for "data" just make sure the right one is connected to the hard drive from the laptop.

Not sure about the Y cables, I've not seen them, can you post a pic?

 

It is a bit more complicated. At a point in time I may have connected to my laptop several accesories (external hdd, cooling pad, other), and I may not have free usb ports, and/or I do not want - just in case - to stress the motherboard with wore power demand....

 

This is not my experience, as my external 3.5" gets an average of 36 mb/s through USB. However this may be due to the larger hard drive, and 2.5" drives may max out at a lower level.

 

What happened Tim? Connected too many devices and the excessive current draw burnt the USB's?