I recently bought a couple of usb external HDD enclosures for 2.5" drives.
One came with a straight male-male usb cable. The other came with the cable pictured.
https://trademe.tmcdn.co.nz/photoserver/full/1495483900.jpg
What is the function of the additional plug? It doesn't work using only the short part of the cable to the drive, so I assume it may be to supply additional power?

rpvr - 2021-02-25 10:33:00

Your pic is a bit too blurry to ascertain whether the 2nd plug is the same as the other two ?

Generally this type of cable has three plugs the same. The single plug goes into the external hard drive and the other two plugs are there because in some circumstances with some hard drives the 'donor' computer wont be able to supply enough power from a single usb outlet. Then you plug both the other usb cables into the computer. This makes more amperage available for the external drive.

If you need that extra power from the other plug its best to not plug both usb plugs into side-by-side ports on the computer. Use one on the front and one on the back of the computer if you can or on opposite sides of the computer, (if laptop for example). Plugs side-by-side can quite often take power from the same source in the computer so may not supply enough Amperage to run the external drive.

Edited by nice_lady at 11:14 am, Thu 25 Feb

nice_lady - 2021-02-25 11:08:00

Its to provide 2 times the usb power because 1 usb can often not provide enough current to spin up a harddrive, so you get the v5 volt from 2 sources= double the current.

intrade - 2021-02-25 11:13:00

Yes, they are all the same. Thanks for the replies. If the extra power is needed, I assume it could be provided form elsewhere, i.e a usb charger.

rpvr - 2021-02-25 11:56:00

rpvr wrote:

Yes, they are all the same. Thanks for the replies. If the extra power is needed, I assume it could be provided form elsewhere, i.e a usb charger.

I would be a little bit careful about suppling the power from 2 total unrelated sources.. e.g from the PC and from a separate USB power supply.. There is potential for earthing problems and the like.

onl_148 - 2021-02-25 12:13:00

rpvr wrote:

Yes, they are all the same. Thanks for the replies. If the extra power is needed, I assume it could be provided form elsewhere, i.e a usb charger.

Hmm..... while that *might* be ok I'm not entirely sure of that and wouldn't advise it. The extra power is usually drawn from the computer you're using.

nice_lady - 2021-02-25 12:17:00

nice_lady wrote:

If you need that extra power from the other plug its best to not plug both usb plugs into side-by-side ports on the computer. Use one on the front and one on the back of the computer if you can or on opposite sides of the computer, (if laptop for example). Plugs side-by-side can quite often take power from the same source in the computer so may not supply enough Amperage to run the external drive.

Then why do they make the lead for the extra power source so short?

rpvr - 2021-02-25 15:11:00

Cheap cable ?

nice_lady - 2021-02-25 15:23:00

rpvr wrote:

Then why do they make the lead for the extra power source so short?

You use 2 USB ports that are next to each other.

gsimpson - 2021-02-25 15:32:00

gsimpson wrote:

You use 2 USB ports that are next to each other.

So you disagree with nice lady at post #2? Good to get all opinions!

rpvr - 2021-02-25 16:06:00

gsimpson wrote:

You use 2 USB ports that are next to each other.

Better to use 2 usb ports which dont' share the same power 'rail' from the psu.

nice_lady - 2021-02-25 16:25:00

intrade wrote:

Its to provide 2 times the usb power because 1 usb can often not provide enough current to spin up a harddrive, so you get the v5 volt from 2 sources= double the current.

Crude explanation above ^^^

In reality, it's to increase the available AMPS.
ALL USB ports run on 5v
Also, USB ports generally only have 500ma (1/2 amp) available per port
Noting that there can be 4 or more ports connected via the motherboard, anything else you have plugged in will be sharing those port Amps.
USB keyboards/ mice/ printers etc etc

The double plug is there to try increase the available amps for your external 2.5" hdd
All electrical devices will only pull what amps they NEED.
Voltages must be correct to avoid damage
You can have a device that needs 1amp but it's fine to run it from a 10amp power pack as long as the volts are correct

Edited by mrfxit at 5:08 pm, Thu 25 Feb

mrfxit - 2021-02-25 17:08:00

nice_lady wrote:

...Generally this type of cable has three plugs the same...

I'm going to disagree too. One end is a male USB type B (commonly used on printers and scanners) and that plugs into the external drive enclosure, they're rated up to 5 amps.

The closest end is a male USB type A which can supply power AND data, and the attached end on the shortest piece is a male USB type A which will only supply power (if you only use this part it won't work with your external disk enclosure).

If you want the maximum power, plug both of the type A's into USB 3 sockets, because they can supply more power than USB 2 or USB 1 sockets. USB 3 sockets are often blue, sometimes red, and USB 2 and 1 are usually white or black.

Edited by gyrogearloose at 7:29 pm, Thu 25 Feb

gyrogearloose - 2021-02-25 19:21:00

intrade wrote:

Its to provide 2 times the usb power...

I disagree with this too, because you could plug 1 end into a USB 3 socket, and one into a USB 2 socket, and that won't be 2 times the power because USB 1 & 2 have lower capacity than USB 3.

USB has a 'handshake' feature where the device you plug in can negotiate the current with the socket you plug it into, so the actual current isn't as simple as using a simple multiplier.

gyrogearloose - 2021-02-25 19:28:00

gyrogearloose wrote:

I'm going to disagree too. One end is a male USB type B (commonly used on printers and scanners) and that plugs into the external drive enclosure, they're rated up to 5 amps.

The closest end is a male USB type A which can supply power AND data, and the attached end on the shortest piece is a male USB type A which will only supply power (if you only use this part it won't work with your external disk enclosure).

If you want the maximum power, plug both of the type A's into USB 3 sockets, because they can supply more power than USB 2 or USB 1 sockets. USB 3 sockets are often blue, sometimes red, and USB 2 and 1 are usually white or black.

Yeah due to the blurriness of that pic I thought MAYBE one of the plugs was usb B - but didn't quite twig to that. You are correct I had one of these long ago. These days of course I have an external drive caddy for 2.5" drives which has only 2x usb A. I was assuming that the third plug would also be usb A.

nice_lady - 2021-02-25 19:54:00

And here's me thinking that the second one was a spare for when the first one failed!

tegretol - 2021-02-25 23:07:00

nice_lady wrote:

Yeah due to the blurriness of that pic I thought MAYBE one of the plugs was usb B - but didn't quite twig to that. You are correct I had one of these long ago. These days of course I have an external drive caddy for 2.5" drives which has only 2x usb A. I was assuming that the third plug would also be usb A.

Sorry for the blurry pic, but your first impression was correct. All three of the connections on that particular lead are type A. The one on the longer lead at RH side of the pic is turned on its side, giving the impression it's different from the others.

Edited by rpvr at 7:49 am, Fri 26 Feb

rpvr - 2021-02-26 07:47:00

I????

nice_lady - 2021-02-26 08:41:00

i wont reply to trolls or know it better smurfs.
i do have a hdd connector and the hdd will spin up and fail to spinn wooom woom woom unless you have usb3 high current port = why you have 2 usb on a y cable to jumpstart the hdd that is what the other plug does.
you live in lalaland if you think it negoshiates power output from the y cable side.
Where the negoshiation is done will be inside the usb on computer side if it is usb3 and has the high current output usually set in bios and done via operation system.
if you have usb1 you will need to plug both ends of the Y cable in to get sufficient current to power the drive.
and yes i do agree it is not a wise idea to use a onhanglow usb plug to add the extra power its better to get it all from the pc laptop via the 2 differnt usb ports.

intrade - 2021-02-26 10:42:00

Gibberish as usual.

vtecintegra - 2021-02-26 10:56:00

intrade wrote:

i wont reply to trolls or know it better smurfs.
i do have a hdd connector and the hdd will spin up and fail to spinn wooom woom woom unless you have usb3 high current port = why you have 2 usb on a y cable to jumpstart the hdd that is what the other plug does.
you live in lalaland if you think it negoshiates power output from the y cable side.
Where the negoshiation is done will be inside the usb on computer side if it is usb3 and has the high current output usually set in bios and done via operation system.
if you have usb1 you will need to plug both ends of the Y cable in to get sufficient current to power the drive.
and yes i do agree it is not a wise idea to use a onhanglow usb plug to add the extra power its better to get it all from the pc laptop via the 2 differnt usb ports.

Power power Oh WHY power ....
The voltage doesn't change, the AMP'S do.
Try doubling voltage on most devices & it will probably fry it.
Try doubling Amps & it all it will do is allow the device to draw it's max rated amount.

When you have a stack of USB devices plugged in, it shares the max amount of Amps that the motherboard can supply for that specific block set of ports.
Hence why using 2 different blocks of usb ports (front & back) can get an external high draw device running again.
Some devices need just a little bit more amps then a single port can supply, hence why 2 plugs works.

The "Y" plug. . .. ...
One branch is a combo data/power plug
The other plug is power only

The device connector .. . ...
Could be anything from about 20 different types of usb plug to custom factory plugs

That cable picture probably has a single usb-b plug on the long length (common printer plug) but could be a usb-b male or female plug (poor photo issue)
The "Y" cable ends because of it's short length will be both usb-a male

Edited by mrfxit at 11:21 am, Fri 26 Feb

mrfxit - 2021-02-26 11:06:00

I deal with this on a regular basis
Prove me wrong & I will happily apologize

But in saying that, I also come across some pretty odd gear from time to time.

mrfxit - 2021-02-26 11:09:00

gyrogearloose wrote:

I disagree with this too, because you could plug 1 end into a USB 3 socket, and one into a USB 2 socket, and that won't be 2 times the power because USB 1 & 2 have lower capacity than USB 3.

USB has a 'handshake' feature where the device you plug in can negotiate the current with the socket you plug it into, so the actual current isn't as simple as using a simple multiplier.

THsi style cable / external disk predates USB 3.0, and is designed for USB 2.0. USB 3.0 has enough grunt for a single cable. USB 2.0 did not ,especially on laptops, or 'extended' USB plugs ie front case USB 2.0 ports often aren't as good as onboard rear ports.

bitsnpieces2020 - 2021-02-26 12:11:00

mrfxit wrote:

I deal with this on a regular basis
Prove me wrong & I will happily apologize

But in saying that, I also come across some pretty odd gear from time to time.

i was amazed as to how many coner the chineese managed to cut.
madman munz is nothing against what they pull off.
example a popcorn maker failed i once got .
it had 240 volt in to th switch to the heat element- to the fan and to neutral. 3 components.
the heat element was the voltage-drop resistor to spin with what was left over the 18 volt fan..
if they can cut corners they will. its why the crap usually go up in smoke quite quick because its all built to only just work for 5 secounds.

Edited by intrade at 1:28 pm, Fri 26 Feb

intrade - 2021-02-26 13:27:00

bitsnpieces2020 wrote:

THsi style cable / external disk predates USB 3.0, and is designed for USB 2.0. USB 3.0 has enough grunt for a single cable. USB 2.0 did not ,especially on laptops, or 'extended' USB plugs ie front case USB 2.0 ports often aren't as good as onboard rear ports.

True in most cases but only really applies when connecting modern gear to modern computers.

I still run in to low amp problems once in awhile because of testing IDE laptop hdd's & 1st gen Sat hdd's.
Most are fine, the odd unit will complain.

Slightly different spec but....
I have a set of 2.5" modern sata hdd's here that can't run from USB.
They need 5v AND 12v

mrfxit - 2021-02-26 15:25:00

bitsnpieces2020 wrote:

THsi style cable / external disk predates USB 3.0, and is designed for USB 2.0. USB 3.0 has enough grunt for a single cable. ...

What you say doesn't satisfy me enough for complete agreement.

I agree this style cable predates USB3 so let's assume it's USB2. The external disk wasn't photographed or described, nor was the second cable the OP said they'd purchased. The other end of the cable is USB type B which the literature says is good for 5 amps.

My reluctance is this: If you use a cable designed for USB2, and plug it into a USB3 socket, I'm thinking you're saying that "USB 3.0 has enough grunt for a single cable" and yet I'm thinking the cable was not manufactured with the USB3 current capability in mind because it predates the USB3 specification (and as intrade says, the manufacturers cut corners and only use the minimum grade components to cut costs.

To me, if I claim that something has USB3 capability end-to-end such as the power capacity rating, then I wouldn't be using a USB2 design cable in the middle. I don't care if the USB2 cable is only 6 inches long, I wouldn't sign my name to it.

gyrogearloose - 2021-02-26 18:31:00