MAX current through a USB-type port.

[bigegg]

I'm currently wiring up a lectronic/lectrickery play area, and I'm wanting to fit some 5v output sockets.

My thoughts are to fit USB style sockets - I know that they are "good" to 2.4A when charging phones etc, but can anyone tell me what the actual max is?
(I'm going to use a 5v/30A PSU to feed around 8 sockets and individually fuse each socket + a 30A fuse on main output).

My Google FU is failing, because I'm getting too many hits for "3.0A" which is a type of connector, not the rating.
Farnell/CPC tech data isn't helping either.

I'm hoping I can get away with 5-8A through each one. (Not all at once!)

 

[Kram]

Usb is not that great, 2-3A is really about the limit, Ive often had poor connections with connectors getting hot at these low currents. Its one of the reasons the idiots designing the standard, have gone with usb-pd which will give upto 20v 5A using the 3.1 connector - but thats using many pins, not just two, and needs fancy communication and variable voltage, rather than just having a dedicated pins. Very few devices support more than the minimum.

Id suggest something like XT30 rc connectors, most of my stuff uses 2mm and 4mm rc bullets but I will swap over to XT60 soon.
www.amazon.co.uk/RUNCCI-Upgrade-Female-Connectors-Battery/dp/B07PC1YKVW/

 

[hotponyshoes]

If you are only using it as a connector then you could connect +/- to 2 pins each and be good for 5amps that way.
Until one of the kids plugs your iPad into it.

I expect the actual rating will depend on the quality/construction of the actual socket rather than the usb destination.

If Farrell doesn't show it in the data sheet for the socket you want to use then get one from a known brand and do some destructive testing!

 

[bigegg]

I've done a bit more browsing around, and I'm going to go with plan B:
Run a 12V line around the room, then add a couple of mains USB sockets, and some 12V:5V vehicle adaptors.
Most of the high-current 5V applications will be for arduino-type stuff which I can add a buck convertor to, to step down from 12v if needed.

Plus, in reality, my projects are going to be 12V based, powered off car batteries, anyway.

 

[hotponyshoes]

I'm presuming this is a soldering/electronics type play area rather than (what I first thought) a kids play area?

Presuming again that you are not actually plugging usb devices into the sockets just stuff that needs 5v power?

If that's the case, and you want 12v power as well why not just mount some multi-way connectors and send all the powers to them?

Something like the one in the photo below,
That's an amphenol ep series, I think good for 20a per pin.
Positive locking but quick release, tough and easy to handle
You can get 4 way versions, put 5v on pin 1&2, 12v on pin 3&4 etc.

Then just wire the plugs appropriately to whatever they are connected to.
You could go fancy using 6 pins if you wanted and let the spare pins control a light that comes on over the socket that's plugged in etc.
Not the cheapest option if you need 8 but it would be a pretty good future-proof low voltage ring main.
You could wire all the terminals up as a ring, connect the 5v psi up now and have the other wires there as/when you need them

 

[bigegg]

I like that idea!
It would mean making up cables, though: whereas I have hundreds of USB cables.

I might use it for the 12V outputs, though...

 

[m_c]

Having just had a quick look at some random datasheets for USB-A connnectors on RS, 1.8A seems to be the common maximum current for main contacts.

 

[hotponyshoes]

I like that idea!
It would mean making up cables, though: whereas I have hundreds of USB cables.

I might use it for the 12V outputs, though...

Won't you have to cut one end off of the usb cables to connect them to the devices anyway though?

USB is not the easiest size to terminate compared to something with a 3mm solder bucket and dasiy-chaining several of them together would be a lot easier if you could twist 2 wires and other both into the same pin and solder.

You also don't pay much more for a 6 pin connector than you do for a 2 pin one.

USB plugs/sockets don't seem to last that well especially if dis/connected under load.

Having said that, usb is cheap, easily available and you can get port savers that you could mount on the wall side if you wanted.
And having the standard sockets would make a lot of sense for anything that does have a usb socket or phones etc that have usb one end and unusual/custom connectors on the other

 

[Kayos]

Just whack the full 30a through it and back it off until things stop melting and smoking

 

[bigegg]

Won't you have to cut one end off of the usb cables to connect them to the devices anyway though?

USB is not the easiest size to terminate compared to something with a 3mm solder bucket and dasiy-chaining several of them together would be a lot easier if you could twist 2 wires and other both into the same pin and solder.

You also don't pay much more for a 6 pin connector than you do for a 2 pin one.

USB plugs/sockets don't seem to last that well especially if dis/connected under load.

Having said that, usb is cheap, easily available and you can get port savers that you could mount on the wall side if you wanted.
And having the standard sockets would make a lot of sense for anything that does have a usb socket or phones etc that have usb one end and unusual/custom connectors on the other

I got a load of PCB USB sockets that I can just solder into my projects, so USB cables would be used as is: the good thing about that is that I can add a poundshop USB powerbank
as my power supply if I want the projects to be portable: and _they_ can be charged with cheap-ish solar panels, making them completely self-contained.

(I'm thinking things like WiFi wildlife cameras, pond/hydroponics sensors/ weather stations type of things)

Each bit would be "plug and play", nothing hardwired, so i could swap the solar panel for a larger one (or a separate feed).
The power bank could be upgraded, The esp32Cam microcontroller could be replaced with a better camera. etc.

Hence me wanting to start with a standard USB power supply- but possibly with a bit more "oomph" if I wanted to power a servo motor, or a GSM/GPS system (which needs a couple of amps to start)

 

[bigegg]

Just whack the full 30a through it and back it off until things stop melting and smoking

"A plumber's guide to Electrics".
Coming soon to Amazon Kindle...

 

[Kayos]

"A plumber's guide to Electrics".
Coming soon to Amazon Kindle...

Is that a USB powered kindle?

 

[bigegg]

Is that a USB powered kindle?

I don't care - I *hate* kindles.

 

[Kayos]

I don't care - I *hate* kindles.

Never used one but I reckon would be a good candidate for the 30a usb power supply

 

[Dev]

5a per socket looks fine - assuming the cable can handle it. Amps are pulled not pushed so it’s unlikely you’ll find a single device that will try and draw 8a - even a rPi 3 at full tilt is only 5a.

USB - Wikipedia

en.wikipedia.org

If you’re drawing more, LED strips or something, then another connector is probably a good idea.

 

[bigegg]

5a per socket looks fine - assuming the cable can handle it. Amps are pulled not pushed so it’s unlikely you’ll find a single device that will try and draw 8a - even a rPi 3 at full tilt is only 5a.

USB - Wikipedia

en.wikipedia.org

If you’re drawing more, LED strips or something, then another connector is probably a good idea.

Thanks!
I thought I'd looked at the wiki...