USB charging points

[Iggifer]

Shaver sockets take no power until you put a plug in. They have a switch wired to the primary of the transformer operated by inserting the plug.
Likewise neons in switches only take power when the switch is on.

That's assuming people turn them off. Plenty of neons on cooker and shower isolators that people never turn off.

 

[JohnW2]

Hager quote theres as 170mW I think. Hardly a deal breaker if I'm honest. As we've discussed before, probably much less than a shaver socket, and probably similar to some neons in switches

... and MK quote 150mW.

Those figures are, indeed, relatively trivial (25p a year or so) but probably appreciably more than an indicator neon; as has been said, shaver sockets are often (usually?) 'switched' by plug insertion.

Kind Regards, John

 

[JohnW2]

Shaver sockets take no power until you put a plug in. They have a switch wired to the primary of the transformer operated by inserting the plug.

That is true of many, maybe most/all.

As for the USB charging sockets, the manufacturers must have thought about it. The running cost of the standby current is trivial, but there is a theoretical safety issue associated with leaving the electronics connected to power 24/7/365. I imagine that the problem may well be that of space (particularly with people moaning that existing ones won't fit into a 25mm back box) and, in particular, of engineering adequate mains-voltage switches for each USB socket without running into problems of LV/ELV separation.

Kind Regards, John

 

[JohnW2]

... and MK quote 150mW. ... Those figures are, indeed, relatively trivial (25p a year or so) but probably appreciably more than an indicator neon ....

I should not make statements without doing the sums!

An accessory indicator neon I've just looked at has a series resistor of 150 kΩ and has about 60 V across the neon when lit. With a typical 240V supply voltage, that means 180 V across the resistor, hence 1.2 mA - and that would amount to 288 mW. If the one I looked at is 'typical', that's almost double the MK USB charger, in which case I apologise for any confusion!

Kind Regards, John

 

[ban-all-sheds]

You seem to be taking the rather garish slogan too literally. I guess you know that the source and sink negotiate a mutually possible voltage and current, up to 100W. Standard available fixed voltages are 5V, 9, 15V and 20V. A max current of 5A could be available at each of those voltages, subject to the cable also responding correctly.

And therefore up to 20A at 5V.

 

[JohnW2]

And therefore up to 20A at 5V.

I don't know the facts, but I suspect that his fourth sentence limits his second one (in terms of what is "mutually possible") - i.e. that the "negotiation of a mutually possible voltage and current" is subject to a maximum of 5A from the charger - hence max power available varies from 25W at 5V to 100W at 20V ... but maybe that's not what he meant.

Kind Regards, John

 

[ban-all-sheds]

Do they claim negotiation capability?

curiously, a search for visually similar images to this:

doesn't find another....

 

[JohnW2]

Do they claim negotiation capability?

I don't know about 'they' but, as you quoted, Detlef certainly made such a claim.

curiously, a search for visually similar images to this: ...

... doesn't find another....

Unusually, that one only shows as a placeholder even in the 'Reply box'. Do you know if anyone is trying to fix this problem?

Kind Regards, John

 

[DetlefSchmitz]

As for the item in the picture, I expect at this point in time it is just a mock-up. It is technically perfectly feasible (I have samples of the hardware required in my lab). The Type-C connector is pretty tiny, so it is limited to 5A. Hence, negotiating higher voltage is the only way to get higher power. Clearly for backward compatibility only 5V is available without negotiation (using the Power Delivery protocol).

 

[ban-all-sheds]

As for the item in the picture, I expect at this point in time it is just a mock-up.