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Re: What sets the charging rate?

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In message <pth9uf.bag.1@ID-201911.user.individual.net>, Frank Slootweg 
<this@ddress.is.invalid> writes:
>Tim <onelydad58@gmail.com> wrote:
>> nospam <nospam@nospam.invalid> wrote in
>> news:261120180852212967%nospam@nospam.invalid:
>>
>> > In article <XnsA9A6336EF683timothybilyahoocom@69.16.179.28>, Tim
>> > <onelydad58@gmail.com> wrote:
[]
>> >> But the USB 3 ports on my computer provide 1.5A, so why doesn't it
>> >> charge at that rate rather than .5A?

(Same reason your 40 watt light bulb doesn't draw the kilowatt or so 
your household lighting circuit can supply.)
>> >
>> > it can provide *up* *to* 1.5a. if a device only requests 500ma, then
>> > that's what it gets.
>> >
>> But it was 'requesting' one amp from the power bank. Why not do so from the
>> wall charger?

Because the two don't speak each other's language. (Or _possibly_ the 
lead is missing the conversation wires.)
>
>  I've also seen such seemingly inconsistent behaviour, i.e. different
>currents drawn from different chargers, while the *highest* current is
>*less* than the capacity of the smallest-capacity charger.
>
>  For example at some state of charge (SoC), my Samsung tablet might
>draw some 750mA from its 2.1A charger, but on a 1A (also Samsung)
>charger, it draws only about half that, 375mA. However, when checking
>the *voltage*, the 2.1A charger delivers 5.18V, while the 1A charger
>delivers 4.96V.
>
>  So I'm quite sure that the 'inconsistent' below-charger-capacity
>charging currents are caused by the chargers delivering slightly
>different voltages.

I'm not. It's certainly _possible_ that the 'phones might monitor the 
voltage available and take current accordingly, but there may also be 
communication between the two. At its simplest, devices will by default 
take no more than half an ampère, because that's what USB 1 and 2 is 
rated at; I read that if the charger contains certain combinations of 
resistors between the power and data lines, the 'phone will "recognise 
it as a proper Apple charger" and draw more. More modern ones may 
actually converse in data terms. (USB3 is rated at a higher default 
level, but the 'phone must know it is a USB3 output - which I presume 
means also be connected with a USB3 cable - before it will draw more 
than the USB2 level.)
>
>  If your power monitors can also measure current and voltage, you might
>want to check if different voltages explain the seemingly inconsistent
>currents.

I doubt it's _purely_ the voltage level that determines it, at least for 
something as sophisticated as a 'phone - not least because the drops in 
the cable probably exceed the variation in supplies. For simpler loads, 
like a desk fan or light, it might have an effect (though only in 
proportion to the voltage variation).
-- 
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Have you ever heard about a petition, disagreed with it, but been frustrated
that there's no way you can *show* that you disagree? If so, have a look at
https://petition.parliament.uk/petitions/232770 - and please pass it on if you
agree, especially to twitter, facebook, gransnet/mumsnet, or any such forum.

You cannot simply assume someone is honest just because they are not an MP.

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Thread

What sets the charging rate? Tim <onelydad58@gmail.com> - 2018-11-23 22:52 +0000
  Re: What sets the charging rate? Tim <onelydad58@gmail.com> - 2018-11-24 04:24 +0000
    Re: What sets the charging rate? micky <NONONOmisc07@bigfoot.com> - 2018-11-25 00:10 -0500
      Re: What sets the charging rate? "Carlos E.R." <robin_listas@es.invalid> - 2018-11-25 14:12 +0100
        Re: What sets the charging rate? micky <NONONOmisc07@bigfoot.com> - 2018-11-25 21:22 -0500
          Re: What sets the charging rate? "Carlos E.R." <robin_listas@es.invalid> - 2018-11-26 15:21 +0100
            Re: What sets the charging rate? micky <NONONOmisc07@bigfoot.com> - 2018-11-27 03:52 -0500
    Re: What sets the charging rate? nospam <nospam@nospam.invalid> - 2018-11-25 00:42 -0500
      Re: What sets the charging rate? Tim <onelydad58@gmail.com> - 2018-11-26 06:18 +0000
        Re: What sets the charging rate? nospam <nospam@nospam.invalid> - 2018-11-26 08:52 -0500
          Re: What sets the charging rate? Tim <onelydad58@gmail.com> - 2018-11-26 14:03 +0000
            Re: What sets the charging rate? nospam <nospam@nospam.invalid> - 2018-11-26 09:11 -0500
              Re: What sets the charging rate? Tim <onelydad58@gmail.com> - 2018-11-26 15:45 +0000
                Re: What sets the charging rate? nospam <nospam@nospam.invalid> - 2018-11-26 10:49 -0500
            Re: What sets the charging rate? Frank Slootweg <this@ddress.is.invalid> - 2018-11-26 16:19 +0000
              Re: What sets the charging rate? 123456789 <12345@12345.com> - 2018-11-26 09:33 -0700
                Re: What sets the charging rate? nospam <nospam@nospam.invalid> - 2018-11-26 11:57 -0500
              Re: What sets the charging rate? "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2018-11-26 16:52 +0000
                Re: What sets the charging rate? nospam <nospam@nospam.invalid> - 2018-11-26 11:57 -0500
                Re: What sets the charging rate? Frank Slootweg <this@ddress.is.invalid> - 2018-11-26 18:49 +0000
                Re: What sets the charging rate? "Carlos E.R." <robin_listas@es.invalid> - 2018-11-27 04:09 +0100
                Re: What sets the charging rate? "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> - 2018-11-27 16:42 +0000
                Re: What sets the charging rate? Tim <onelydad58@gmail.com> - 2018-11-27 22:43 +0000
                Re: What sets the charging rate? "Carlos E.R." <robin_listas@es.invalid> - 2018-11-28 14:08 +0100
                Re: What sets the charging rate? Andy Burns <usenet@andyburns.uk> - 2018-11-28 13:27 +0000
                Re: What sets the charging rate? "Carlos E.R." <robin_listas@es.invalid> - 2018-11-28 14:06 +0100

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