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USB charging points

Discussion in 'Electrics UK' started by prefab, 7 Aug 2017.

  1. Iggifer

    Iggifer

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    That's assuming people turn them off. Plenty of neons on cooker and shower isolators that people never turn off.
     
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  3. JohnW2

    JohnW2

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    ... 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
     
  4. JohnW2

    JohnW2

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    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
     
  5. JohnW2

    JohnW2

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    I should not make statements without doing the sums! :oops:

    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
     
  6. ban-all-sheds

    ban-all-sheds

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    And therefore up to 20A at 5V.
     
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  8. JohnW2

    JohnW2

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    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
     
  9. ban-all-sheds

    ban-all-sheds

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    Do they claim negotiation capability?

    curiously, a search for visually similar images to this:

    [​IMG]

    doesn't find another....
     
  10. JohnW2

    JohnW2

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

    DetlefSchmitz

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    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).
     
  12. ban-all-sheds

    ban-all-sheds

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    [​IMG]
     
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    DIYnot Local

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