USB 3.0 hubs that can support several bus powered 1A devices simultaneously? - Page 1
Forum section: electronics / general

author: salil
author_rank: Regular Contributor
timestamp: March 22, 2015, 05:16:08 am
content: Do they exist? I see in the description of a lot of powered USB 3.0 hubs that they can only support one bus powered external HDD at a time. I'm trying to find a powered USB 3.0 hub that will support several 1A USB devices (optical drives, bus powered ext HDDs, phones, etc), but am having trouble finding anything but hubs with lots of ports that are each limited to 500mA...the total current is more than a bus powered hub could probably provide but I can't power a lot of high current devices. Any thoughts?Edit: I've attached some pics of this usb 3.0 hub I recently purchased:http://www.amazon.com/gp/aw/d/B00S4UDBGI/ref=mp_s_a_1_10?qid=1427000301&sr=8-10&pi=AC_SX110_SY165_QL70&keywords=usb+hub+3.0+4a

author: Rerouter
author_rank: Super Contributor
timestamp: March 22, 2015, 05:21:00 am
content: more likely the shitty little plug-pack they come with can only support 1 device at a time, if you where to swap it out for say a 3A plugpack then you would likely be able to pull it off, or higher current again,now in reality the trace width they use on the board may not be wide enough to support several amps of current, but i would hope so.

author: salil
author_rank: Regular Contributor
timestamp: March 22, 2015, 05:25:39 am
content: I recently purchased this one:https://www.amazon.com/gp/product/B00S4UDBGI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1And it comes with a 12v/4A power supply but so far, it appears to only supply 500 mA per data port.Ps: I noticed after the purchasing that the item description says that it only supports 1 bus powered ext hdd...so I'm now looking for something that will support more than one.

author: Rerouter
author_rank: Super Contributor
timestamp: March 22, 2015, 06:30:34 am
content: ... get out your multimeter, with your hub disconnected from power and data, measure the resistance between the +5V rail pins, and then between the ground pins on the ports including the charging ports, you have about a 99% chance they are all connected together, and there is no form of limiting per port,as such you should be able to use multiple externals per hub, the issue would be if you had say 4 plugged in at once and connected power to the hub, the surge required by more than one hard drive would pull more than the plugpack can supply and the voltage would drop like a rock resulting in a possible cycle of the drives all trying to turn over, get killed by brownout and wait till it rises again, for this the only way around it would be opening the hub and fitting a sodding big capacitor, or opening the power supply and fitting a sodding big cap,however for use where its always powered, you should be fine as long as you go one drive at a time, and wait say 10 seconds for the drive to come fully up to speed,

author: salil
author_rank: Regular Contributor
timestamp: March 22, 2015, 08:24:58 am
content: Please forgive my ignorance, but what is a "sodding big capacitor"?

author: salil
author_rank: Regular Contributor
timestamp: March 22, 2015, 08:28:41 am
content: Also, why would a 12v/4A power supply not be able to supply enough current for 4 bus powered USB external hard drives (assuming step down circuitry in the hub can handle the current)? They're only around 1A @5v, right? So less than .5A @12v each.I've added some pictures of the hub to the OP.

author: Howardlong
author_rank: Super Contributor
timestamp: March 22, 2015, 09:12:21 am
content: I had a similar experience with one of these bad boyshttp://manhattan-products.com/barcode/161718.I was building a flight sim setup with 20 odd USB panel controls, I didn't think the devices would draw the full 4A at 5V but they did, and then some.I had to switch to three separate ten port USB hubs and carefully distribute the current loading.The symptoms were that either device(s) would randomly not work, or Windows reported it was out of resources. I assumed it was a bandwidth problem, but it turned out to be power. I must've wasted a few days of my life trying to understand the problem.In retrospect, it's a bit stupid providing a 28 port USB hub with so little power capability.

author: Rerouter
author_rank: Super Contributor
timestamp: March 22, 2015, 11:12:12 am
content: a sodding big capacitor is a stylized way of saying a large value capacitor, e.g. 20,000uF,the fact that its going through a switchmode converter is probably your first clue of where the limit comes from, most modern ones in this type environment would have some form of current limiting, thus when your hard drive tries to turn over and would happily draw 17A for a few millisecond if it could, it hits the limit and voltage goes down, and they likely sized the output capacitance of the hub to be just big enough to cover one drives demand,now to make clear you should be able to connect more than one external at a time, heck i can do that on my unpowered hub, but you have to start them one after another, or the demand of all the devices at once is just to much and the brownout circuit kicks in, as the largest power requirement of a drive is getting it spinning,final point for the night, have you actually tried connecting as many drives / devices as possible to the thing and seen if it works? or are you fussing over a cheap product only claiming what they can promise to be true in all situations, I've done things with USB that break the specs before, heck I've had a webcam running at the end of a 60m usb extension lead, until you try it and can definitively say this doesn't work, why make a fuss?

author: Stigaard
author_rank: Contributor
timestamp: March 22, 2015, 11:45:28 am
content: There seem to be industrial devices available, which seem to promise the individual current handling you are looking for4 porthttps://www.usbgear.com/computer_cable_details.cfm?sku=USBG-4U3ML&cats=132&catid=434%2C433%2C132%2C131%2C111%2C187%2C188%2C104%2C653%2C210%2C2127 porthttps://www.usbgear.com/computer_cable_details.cfm?sku=USBG-7U3ML&cats=132&catid=434%2C433%2C132%2C131%2C111%2C187%2C188%2C104%2C653%2C210%2C21216 porthttps://www.usbgear.com/computer_cable_details.cfm?sku=USB3-16U1&cats=132&catid=434%2C433%2C132%2C131%2C111%2C187%2C188%2C104%2C653%2C210%2C212I have no experience with them however so no promises

author: Whales
author_rank: Super Contributor
timestamp: March 22, 2015, 08:11:35 pm
content: Quote from: salil on March 22, 2015, 08:24:58 amSodding = very

author: Len
author_rank: Frequent Contributor
timestamp: March 22, 2015, 09:10:18 pm
content: Quote from: salil on March 22, 2015, 08:28:41 amHere's one possible reason:

author: salil
author_rank: Regular Contributor
timestamp: April 25, 2015, 10:01:31 am
content: Quote from: Len on March 22, 2015, 09:10:18 pmI've tried other 12v DC power supplies on hubs that weren't supporting 4 x bus powered external hard drives simultaneously and it didn't make any difference. I've drawn as much as 9A from some of the 12v power supplies I have (different application).

author: senso
author_rank: Frequent Contributor
timestamp: April 25, 2015, 09:37:45 pm
content: What kind of loads are you using to test the hub?