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What sets the charging rate?

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  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

Page 2 of 2 — ← Prev page 1 [2]

#57931

On 26/11/2018 17.52, J. P. Gilliver (John) wrote:
> 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.)

Well, not exactly: the light bulb doesn't have a controller, and it
doesn't negotiate. It is purely ohm law, with a relatively fixed plain
resistor (except that the resistor gets so hot, that resistance
increases notably with the temperature).

So the house supplies a fixed voltage and you connect a fixed resistor:
the current is determined from both. There is no limitation in the
circuit on current or power: but if the resistor is too low, the fuse blows.

Intelligent devices can have batteries with regulation. The apparent
resistance the "battery" has varies so that it draws more or less
current as needed.

-- 
Cheers, Carlos.

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#57932

In message <35pucf-i3d.ln1@Telcontar.valinor>, Carlos E.R. 
<robin_listas@es.invalid> writes:
>On 26/11/2018 17.52, J. P. Gilliver (John) wrote:
>> 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.)
>
>Well, not exactly: the light bulb doesn't have a controller, and it
>doesn't negotiate. It is purely ohm law, with a relatively fixed plain
>resistor (except that the resistor gets so hot, that resistance
>increases notably with the temperature).
>
>So the house supplies a fixed voltage and you connect a fixed resistor:
>the current is determined from both. There is no limitation in the
>circuit on current or power: but if the resistor is too low, the fuse blows.
>
>Intelligent devices can have batteries with regulation. The apparent
>resistance the "battery" has varies so that it draws more or less
>current as needed.
>
I know, it was a poor example: I was just a bit shocked that someone 
could say "my charger delivers 1.5A"; he didn't realise that the truth 
was that his charger _can_ deliver 1.5A, but doesn't necessarily do so 
if the device doesn't suck that much. I suppose I could have said "your 
charger doesn't deliver _anything_ if nothing is connected to it", but 
that wasn't as good, I thought.

Interesting off-topic sidebar: nearly forty years ago I briefly worked 
in the electricity supply industry, where they had (presumably do still) 
things called "current transformers", usually abbreviated to CT, which 
worked counter to how we're used to thinking: they delivered a _current_ 
proportional to the current in the primary (often a "bar primary"!), and 
did so no matter what. They were intended for instrumentation (and thus 
control of course). Unlike conventional power sources, they were quite 
happy to be shorted: they'd deliver their rated current through the 
short. In fact you normally _did_ leave them shorted when not connected 
to anything - because they'd try to deliver that current regardless, and 
if you left them _open_ circuit, would overvoltage and damage 
themselves. I never did figure out how they worked (I don't remember 
trying very hard, I admit. I'm pretty sure they were passive devices 
though - just coils and cores, no electronics). Their advantage was 
that, no matter how long the cable run between them and the (say) meter 
you connected them to (could be many tens of yards - possibly miles I 
think), the current would indicate.
-- 
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.

offensive speech is something to be protected, not celebrated.
- "yoni", 2015-8-5

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#57939

"J. P. Gilliver (John)" <G6JPG-255@255soft.uk> wrote in
news:zUesCwyzPX$bFw5D@255soft.uk: 

> In message <35pucf-i3d.ln1@Telcontar.valinor>, Carlos E.R. 
> <robin_listas@es.invalid> writes:
>>On 26/11/2018 17.52, J. P. Gilliver (John) wrote:
>>> 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.)
>>
>>Well, not exactly: the light bulb doesn't have a controller, and it
>>doesn't negotiate. It is purely ohm law, with a relatively fixed plain
>>resistor (except that the resistor gets so hot, that resistance
>>increases notably with the temperature).
>>
>>So the house supplies a fixed voltage and you connect a fixed
>>resistor: the current is determined from both. There is no limitation
>>in the circuit on current or power: but if the resistor is too low,
>>the fuse blows. 
>>
>>Intelligent devices can have batteries with regulation. The apparent
>>resistance the "battery" has varies so that it draws more or less
>>current as needed.
>>
> I know, it was a poor example: I was just a bit shocked that someone 
> could say "my charger delivers 1.5A"; he didn't realise that the truth
> was that his charger _can_ deliver 1.5A, but doesn't necessarily do so
> if the device doesn't suck that much. I suppose I could have said
> "your charger doesn't deliver _anything_ if nothing is connected to
> it", but that wasn't as good, I thought.
> 
You are missing the point. My point was, the charger was capable of 
delivering 1.5A, and the question was why isn't the device doing so. The 
device had shown it was capable of using a 1.0A charge current when 
plugged into the powerbank, so why wasn't it using more than .5A from the 
charger. I understand now what the probable reason is, thanks to the 
pointer to the very useful Wikipedia entry on USB(Power) pointed to by 
another respondent.

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#57950

On 27/11/2018 23.43, Tim wrote:
> "J. P. Gilliver (John)" <G6JPG-255@255soft.uk> wrote in
> news:zUesCwyzPX$bFw5D@255soft.uk: 
> 
>> In message <35pucf-i3d.ln1@Telcontar.valinor>, Carlos E.R. 
>> <robin_listas@es.invalid> writes:
>>> On 26/11/2018 17.52, J. P. Gilliver (John) wrote:
>>>> 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.)
>>>
>>> Well, not exactly: the light bulb doesn't have a controller, and it
>>> doesn't negotiate. It is purely ohm law, with a relatively fixed plain
>>> resistor (except that the resistor gets so hot, that resistance
>>> increases notably with the temperature).
>>>
>>> So the house supplies a fixed voltage and you connect a fixed
>>> resistor: the current is determined from both. There is no limitation
>>> in the circuit on current or power: but if the resistor is too low,
>>> the fuse blows. 
>>>
>>> Intelligent devices can have batteries with regulation. The apparent
>>> resistance the "battery" has varies so that it draws more or less
>>> current as needed.
>>>
>> I know, it was a poor example: I was just a bit shocked that someone 
>> could say "my charger delivers 1.5A"; he didn't realise that the truth
>> was that his charger _can_ deliver 1.5A, but doesn't necessarily do so
>> if the device doesn't suck that much. I suppose I could have said
>> "your charger doesn't deliver _anything_ if nothing is connected to
>> it", but that wasn't as good, I thought.
>>
> You are missing the point. My point was, the charger was capable of 
> delivering 1.5A, and the question was why isn't the device doing so. 

Because the load doesn't draw that much current :-)

-- 
Cheers, Carlos.

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#57951

Tim wrote:

> You are missing the point. My point was, the charger was capable of
> delivering 1.5A, and the question was why isn't the device doing so

Most likely the combination of resistors between GND/+5V/D+/D- in the 
charger aren't what the tablet would like to see, to confirm it is 
allowed more than 0.5A

<https://www.maximintegrated.com/en/app-notes/index.mvp/id/5801>

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#57949

On 27/11/2018 17.42, J. P. Gilliver (John) wrote:
> In message <35pucf-i3d.ln1@Telcontar.valinor>, Carlos E.R.
> <robin_listas@es.invalid> writes:
>> On 26/11/2018 17.52, J. P. Gilliver (John) wrote:
>>> 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.)
>>
>> Well, not exactly: the light bulb doesn't have a controller, and it
>> doesn't negotiate. It is purely ohm law, with a relatively fixed plain
>> resistor (except that the resistor gets so hot, that resistance
>> increases notably with the temperature).
>>
>> So the house supplies a fixed voltage and you connect a fixed resistor:
>> the current is determined from both. There is no limitation in the
>> circuit on current or power: but if the resistor is too low, the fuse
>> blows.
>>
>> Intelligent devices can have batteries with regulation. The apparent
>> resistance the "battery" has varies so that it draws more or less
>> current as needed.
>>
> I know, it was a poor example: I was just a bit shocked that someone
> could say "my charger delivers 1.5A"; he didn't realise that the truth
> was that his charger _can_ deliver 1.5A, but doesn't necessarily do so
> if the device doesn't suck that much. I suppose I could have said "your
> charger doesn't deliver _anything_ if nothing is connected to it", but
> that wasn't as good, I thought.

Indeed :-)

> 
> Interesting off-topic sidebar: nearly forty years ago I briefly worked
> in the electricity supply industry, where they had (presumably do still)
> things called "current transformers", usually abbreviated to CT, which
> worked counter to how we're used to thinking: they delivered a _current_
> proportional to the current in the primary (often a "bar primary"!), and
> did so no matter what. They were intended for instrumentation (and thus
> control of course). Unlike conventional power sources, they were quite
> happy to be shorted: they'd deliver their rated current through the
> short. In fact you normally _did_ leave them shorted when not connected
> to anything - because they'd try to deliver that current regardless, and
> if you left them _open_ circuit, would overvoltage and damage
> themselves. I never did figure out how they worked (I don't remember
> trying very hard, I admit. I'm pretty sure they were passive devices
> though - just coils and cores, no electronics). Their advantage was
> that, no matter how long the cable run between them and the (say) meter
> you connected them to (could be many tens of yards - possibly miles I
> think), the current would indicate.

Interesting. I heard of them, but never saw one.

We did use "current sources" in circuit theory - and they were initially
a bit of a conflict to understand :-)

-- 
Cheers, Carlos.

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