USB hub - help - don't want to break something!

Grangey.

Distinguished Member
Hi all,

Don't know where else to put this so hopefully one of you can help!

I've run out of "hidden" socket space on my AV wall sadly, and need to create one magically. To do this, I've realised I've got 4 devices that are powered in their rear via USB cable but each take up independant plug sockets.

I think it must be possible to replace these 4 plugs, with 1, which powers a USB hub, and this is where you're input would be appreciated.

Devices:
  • Nest Thermostat in a stand- from a google, suggests requests 0.15A (150mA) at 12 VDC
  • Echo Dot: Rated 1A @ 5.1V
  • Harmony Remote: Rated 1A @ 5.15V
  • Harmony Hub: Rated 1A @ 5.15V
I'm not an electrician, so what I don't want to do is order any old up with the wrong V or A ratings and risk frying a device. So can anyone point me to a powered hub that could safely power these in alignment with their ratings?

I've found this:
https://www.amazon.co.uk/dp/B01LRWN...olid=2JUREJKQYSE2J&psc=1&ref_=lv_ov_lig_dp_it

But as none of these devices are smartphones, not sure if said device could know the different amp requirements for each of these kind of devices... and not being electrically minded, don't know what the impact of plugging these into 2.4a type adapters would be, or whether I should try to get something like this that has specific ports with different amp ratings:

https://www.amazon.co.uk/WANLONGXIN...95586&sr=8-30&keywords=usb+power+hub+mains+5v

Sadly adding another socket on the wall or a larger extension lead aren't options.

Thanks in advance for your help!
 

IronGiant

Moderator
The first one will be fine. (The second might be too but looks a bit naff). But only for the ones requiring 5.1V. Are you sure the nest requires 12V?
 

IronGiant

Moderator
Ah, it's OK, it either needs a 12V power plug or a 5.1V USB...
 

IronGiant

Moderator
  • Echo Dot: Rated 1A @ 5.1V
  • Harmony Remote: Rated 1A @ 5.15V
  • Harmony Hub: Rated 1A @ 5.15V
BTW, I power these 3 off a similar device, so I know they will be OK. And as your Nest has an alternative USB input to the powerplug I'm sure that will be fine too.
 

nvingo

Distinguished Member
Even though many of the descriptions use the word 'hub' in them, I don't consider these to be hubs; to my mind a hub manages data, these are just power supplies (chargers) that happen to have multiple output sockets.

I like the look of these two (copy-paste into ebay search):
"9.6A 4 Port USB UK Desktop Mains Wall Multi Fast Charger for LG G4 / G4 Pro" and
"4-Port USB Wall Charger UK Mains Plug Travel Power Adaptor Plug for iPhone iPad"
the first has an unpluggable mains lead in case you need to thread it through cabinet holes,
the second has a digital meter display if that's helpful, though again it has unpluggable mains lead but it's US plug, you would need to source a UK lead for it (looks to be standard audio equipment connector but can't be sure), or cut off the plug and wire on a standard UK 3-pin.
 

EndlessWaves

Distinguished Member
USB is a little different because it started out as a data connection providing power to connected devices and there wasn't any provision to begin with for it to act in a pure power supply capacity. So as it's evolved the terminology has sometimes got a bit tangled.

A hub is for connecting for devices to a host device (computer, smartphone, TV etc.). If it doesn't have the outgoing connection to a host device it's simply a power supply (aka charger) and not a hub.

Additionally it's not possible to just draw power from a USB connector as a device can from a normal power supply. They have to negotiate with the port they're connecting to and request a certain amount of power.

Unfortunately the protocols for this negotiation have had rather a rocky road, with a couple of different official ones and several unofficial ones. And a lot of reluctance on the part of device manufacturer and power supply manufacturers to make it clear what they use and support.

You can't just look at power output, because if the charger doesn't understand the way the device is requesting the power it's not going to deliver it.

But on to specifics. The [email protected] devices are likely to be using USB Battery Charging which is the first official power standard and widely supported these days. They may also be using the Apple 1A standard, although that's also widely supported.

The Nest Thermostat values you've quoted are unusual. There are a couple of USB standards that can deliver 12V (USB Power Delivery and later versions of Qualcomm's Quickcharge) but it would be strange to use them on a 0.36W device when there are much better supported standards. I would double check those, perhaps drop them an e-mail.
 

IronGiant

Moderator
The Nest Thermostat values you've quoted are unusual. There are a couple of USB standards that can deliver 12V (USB Power Delivery and later versions of Qualcomm's Quickcharge) but it would be strange to use them on a 0.36W device when there are much better supported standards. I would double check those, perhaps drop them an e-mail.

I think you'll find that the Nest can be powered in one of two ways, either with a standard 5V usb if being used as a wireless free standing device, or by hard wiring into a 12V supply from the boiler/heat link using an existing low voltage thermostat's wiring.
 

Grangey.

Distinguished Member
Thanks all!

Does seem I got the Nest values wrong, it is 5V from USB, 12V is only relevant when wired direct to the boiler.

I think I was most concerned about the variety of amp ratings and how an appropriate hub power supply would deal with this not really understanding what they mean other than fuse come with these ratings which implies safety to me.

Great to know Im on the right lines though, will get ordering! :)
 

EndlessWaves

Distinguished Member
I think I was most concerned about the variety of amp ratings and how an appropriate hub power supply would deal with this not really understanding what they mean other than fuse come with these ratings which implies safety to me.

Very little unfortunately. You can guess that a device claiming 2.4A supports Apple's last proprietary standard (used in the early iPads before they swapped to USB Power Delivery), as that was it's maximum output. But if it doesn't support the way your devices are requesting power it'll drop back to the 0.5A that was the standard when USB got started to used as a power supply, and thus supported by everything.

But the upside of all this complexity is that you're not going to damage anything with an incorrect USB power supply like you could with a normal power supply. It just won't work properly.

In practice it doesn't sound like any of the devices draw enough to need the latest standards, so any USB power supply less than 3-4 years old should work.
 

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