I'd assumed he knew that but you can get much bigger ones with multiple
sockets. Call me old fashioned but despite the inefficiency, a good set of
lead Acid leisure batteries an invertors some charging apparatus that does
it from multiple local sources or the mains with some low voltage outlets
too seems more versatile to me.
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"alan_m" <junk@admac.myzen.co.uk> wrote in message
news:jsi4luFa41dU1@mid.individual.net...
> On 03/11/2022 15:10, Scott wrote:
>> Could someone check my homework please :-)
>>
>> I am thinking about a USB powered lamp in the event of future power
>> cuts - linked to a powerbank. I believe the typical output from a
>> powerbank is 2 amps at 5 volts. I assume an LED bulb will consume no
>> more than 5 watts. If 2 amps at 5 volts is 10 watts (V x I ), this
>> should be more than adequate to power the lamp.
>>
>> Am I missing something?
>
>
> The capacity of the battery. The power bank may supply 2A @ 5V but for
> only 10 minutes.
>
>
> --
> mailto : news {at} admac {dot} myzen {dot} co {dot} uk
>

Brian Gaff wrote:

> I think officially 1 amp is the max current of standard USB sockets. Even
> that seems to be pushing it a bit in my view.

What is your view on USB type C sockets allowing up to 5A at 48V ?

Brian Gaff <brian1gaff@gmail.com> wrote

> I think officially 1 amp is the max current of standard USB sockets.

Not anymore.
https://en.wikipedia.org/wiki/USB_hardware#Power

> Even that seems to be pushing it a bit in my view.

Nope.

On Thu, 3 Nov 2022 22:31:18 +0000, Chris Green <cl@isbd.net> wrote:

>Scott <newsgroups@gefion.myzen.co.uk> wrote:
>> On Thu, 3 Nov 2022 21:44:35 +0000, Chris Green <cl@isbd.net> wrote:
>>
>> >Scott <newsgroups@gefion.myzen.co.uk> wrote:
>> >>
>> >> I already have an LED lantern for that purpose (which is rechargeable
>> >> but a very large battery). I am now looking for a desk type lamp so I
>> >> can read in bed if early nights become mandated.
>> >
>> >Get a Kobo or a Kindle, much easier than a real book for reading in
>> >bed and they have long-lasting backlights. I prefer Kobo mostly
>> >because I can borrow books from my local (UK) library with it
>> >directly.
>>
>> I was given a Kindle about eight years ago. Is it likely to be okay
>> now, if I can find it?
>
>Possibly, plug it in to charge and leave it for a day (or more) and
>see if it comes to life.

What about software and stuff? I know support falls away with iPads
and Android, for example.

Scott <newsgroups@gefion.myzen.co.uk> wrote:
> On Thu, 3 Nov 2022 22:31:18 +0000, Chris Green <cl@isbd.net> wrote:
>
> >Scott <newsgroups@gefion.myzen.co.uk> wrote:
> >> On Thu, 3 Nov 2022 21:44:35 +0000, Chris Green <cl@isbd.net> wrote:
> >>
> >> >Scott <newsgroups@gefion.myzen.co.uk> wrote:
> >> >>
> >> >> I already have an LED lantern for that purpose (which is rechargeable
> >> >> but a very large battery). I am now looking for a desk type lamp so I
> >> >> can read in bed if early nights become mandated.
> >> >
> >> >Get a Kobo or a Kindle, much easier than a real book for reading in
> >> >bed and they have long-lasting backlights. I prefer Kobo mostly
> >> >because I can borrow books from my local (UK) library with it
> >> >directly.
> >>
> >> I was given a Kindle about eight years ago. Is it likely to be okay
> >> now, if I can find it?
> >
> >Possibly, plug it in to charge and leave it for a day (or more) and
> >see if it comes to life.
>
> What about software and stuff? I know support falls away with iPads
> and Android, for example.

Doesn't really matter, My wife has a very ancient Kindle which still
works fine with downloaded Amazon books. It can of course still read
PDFs and such as well.

--
Chris Green
·

S Viemeister <firstname@lastname.oc.ku> wrote:
> On 03/11/2022 21:44, Chris Green wrote:
> > Scott <newsgroups@gefion.myzen.co.uk> wrote:
> >>
> >> I already have an LED lantern for that purpose (which is rechargeable
> >> but a very large battery). I am now looking for a desk type lamp so I
> >> can read in bed if early nights become mandated.
> >
> > Get a Kobo or a Kindle, much easier than a real book for reading in
> > bed and they have long-lasting backlights. I prefer Kobo mostly
> > because I can borrow books from my local (UK) library with it
> > directly.
> >
> I borrow books from my local Scottish library with my Kindle.

Yes, I think it varies from local authority to local authority. Also
things have got better since I bought my Kobo, I think.

When you say "I borrow books from my local Scottish library with my
Kindle" how does it work? My Kobo just synchronises with my library
and any borrowed books appear on the Kobo. I can do the borrowing on
a computer or on the Kobo.

--
Chris Green
·

Brian Gaff <brian1gaff@gmail.com> wrote:
> I think officially 1 amp is the max current of standard USB sockets. Even
> that seems to be pushing it a bit in my view.

I believe USB2 is 500mA, USB3 (in its many incarnations) can be a lot
more but there are so many variations there isn't really one
definitive value.

--
Chris Green
·

On Fri, 4 Nov 2022 10:17:36 +0000, Chris Green <cl@isbd.net> wrote:

>Scott <newsgroups@gefion.myzen.co.uk> wrote:
>> On Thu, 3 Nov 2022 22:31:18 +0000, Chris Green <cl@isbd.net> wrote:
>>
>> >Scott <newsgroups@gefion.myzen.co.uk> wrote:
>> >> On Thu, 3 Nov 2022 21:44:35 +0000, Chris Green <cl@isbd.net> wrote:
>> >>
>> >> >Scott <newsgroups@gefion.myzen.co.uk> wrote:
>> >> >>
>> >> >> I already have an LED lantern for that purpose (which is rechargeable
>> >> >> but a very large battery). I am now looking for a desk type lamp so I
>> >> >> can read in bed if early nights become mandated.
>> >> >
>> >> >Get a Kobo or a Kindle, much easier than a real book for reading in
>> >> >bed and they have long-lasting backlights. I prefer Kobo mostly
>> >> >because I can borrow books from my local (UK) library with it
>> >> >directly.
>> >>
>> >> I was given a Kindle about eight years ago. Is it likely to be okay
>> >> now, if I can find it?
>> >
>> >Possibly, plug it in to charge and leave it for a day (or more) and
>> >see if it comes to life.
>>
>> What about software and stuff? I know support falls away with iPads
>> and Android, for example.
>
>Doesn't really matter, My wife has a very ancient Kindle which still
>works fine with downloaded Amazon books. It can of course still read
>PDFs and such as well.

I'll look into it. Nothing to lose.

On Thu, 3 Nov 2022 22:43:25 +0000, S Viemeister
<firstname@lastname.oc.ku> wrote:

>On 03/11/2022 21:44, Chris Green wrote:
>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>
>>> I already have an LED lantern for that purpose (which is rechargeable
>>> but a very large battery). I am now looking for a desk type lamp so I
>>> can read in bed if early nights become mandated.
>>
>> Get a Kobo or a Kindle, much easier than a real book for reading in
>> bed and they have long-lasting backlights. I prefer Kobo mostly
>> because I can borrow books from my local (UK) library with it
>> directly.
>>
>I borrow books from my local Scottish library with my Kindle.

Is there a fine for late return :-)

On 04/11/2022 08:58, Andy Burns wrote:
> Brian Gaff wrote:
>
>> I think officially 1 amp is the max current of standard USB sockets. Even
>> that seems to be pushing it a bit in my view.
>
> What is your view on USB type C sockets allowing up to 5A at 48V ?

When I saw the spec now mentioned voltages of up to 50.9V (48V + a 5%
tolerance) I was left wondering if there were implications for touch
voltages in domestic installations. E.g. if a USB socket tests just
over 50V?

--
Robin
reply-to address is (intended to be) valid

On Fri, 4 Nov 2022 10:22:45 +0000, Chris Green <cl@isbd.net> wrote:

>Brian Gaff <brian1gaff@gmail.com> wrote:
>> I think officially 1 amp is the max current of standard USB sockets. Even
>> that seems to be pushing it a bit in my view.
>
>I believe USB2 is 500mA, USB3 (in its many incarnations) can be a lot
>more but there are so many variations there isn't really one
>definitive value.

Apart from the risk of injury, is there also a risk of damaging the
equipment by touching the live part of the socket?

On 03/11/2022 15:42, alan_m wrote:
> On 03/11/2022 15:32, Andy Burns wrote:
>> alan_m wrote:
>>
>>
>>> The capacity of the battery. The power bank may supply 2A @ 5V but
>>> for only 10 minutes.
>>
>> Also the powerbank may quote the capacity as e.g. 20,000mAh (why not
>> 20Ah?)
>
> More zeros mean a better product :) It also depends on if it's a Chinese
> 20Ah or a real world 20Ah.  Ebay is full of batteries claimed to be 4x
> the capacity of those same size, same technology, batteries from
> reputable manufacturers.
>
The trick is that 20,000mAh is the lifetime capacity, ie keep recharging
and using it and it'll give that amount in total till it packs up :-)

--
Cheers
Clive

On Friday, 4 November 2022 at 11:01:33 UTC, Scott wrote:
> On Fri, 4 Nov 2022 10:22:45 +0000, Chris Green <c...@isbd.net> wrote:
>
> >Brian Gaff <brian...@gmail.com> wrote:
> >> I think officially 1 amp is the max current of standard USB sockets. Even
> >> that seems to be pushing it a bit in my view.
> >
> >I believe USB2 is 500mA, USB3 (in its many incarnations) can be a lot
> >more but there are so many variations there isn't really one
> >definitive value.
> Apart from the risk of injury, is there also a risk of damaging the
> equipment by touching the live part of the socket?

The higher voltages need to be negotiated, so they will not be present without
anything being plugged in.
John

Scott <newsgroups@gefion.myzen.co.uk> wrote:
> On Thu, 3 Nov 2022 22:43:25 +0000, S Viemeister
> <firstname@lastname.oc.ku> wrote:
>
> >On 03/11/2022 21:44, Chris Green wrote:
> >> Scott <newsgroups@gefion.myzen.co.uk> wrote:
> >>>
> >>> I already have an LED lantern for that purpose (which is rechargeable
> >>> but a very large battery). I am now looking for a desk type lamp so I
> >>> can read in bed if early nights become mandated.
> >>
> >> Get a Kobo or a Kindle, much easier than a real book for reading in
> >> bed and they have long-lasting backlights. I prefer Kobo mostly
> >> because I can borrow books from my local (UK) library with it
> >> directly.
> >>
> >I borrow books from my local Scottish library with my Kindle.
>
> Is there a fine for late return :-)

Ha ha. The book just disappears from your reader at the end of the
borrowing period (or at least that's what happens on my Kobo).

--
Chris Green
·

Scott <newsgroups@gefion.myzen.co.uk> wrote:
> On Fri, 4 Nov 2022 10:22:45 +0000, Chris Green <cl@isbd.net> wrote:
>
> >Brian Gaff <brian1gaff@gmail.com> wrote:
> >> I think officially 1 amp is the max current of standard USB sockets. Even
> >> that seems to be pushing it a bit in my view.
> >
> >I believe USB2 is 500mA, USB3 (in its many incarnations) can be a lot
> >more but there are so many variations there isn't really one
> >definitive value.
>
> Apart from the risk of injury, is there also a risk of damaging the
> equipment by touching the live part of the socket?

The 'a lot more' is by negotiation, I don't think there should ever be
more than 5v when nothing is connected.

--
Chris Green
·

On 04/11/2022 10:21, Chris Green wrote:
> S Viemeister <firstname@lastname.oc.ku> wrote:
>> On 03/11/2022 21:44, Chris Green wrote:
>>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>>
>>>> I already have an LED lantern for that purpose (which is rechargeable
>>>> but a very large battery). I am now looking for a desk type lamp so I
>>>> can read in bed if early nights become mandated.
>>>
>>> Get a Kobo or a Kindle, much easier than a real book for reading in
>>> bed and they have long-lasting backlights. I prefer Kobo mostly
>>> because I can borrow books from my local (UK) library with it
>>> directly.
>>>
>> I borrow books from my local Scottish library with my Kindle.
>
> Yes, I think it varies from local authority to local authority. Also
> things have got better since I bought my Kobo, I think.
>
> When you say "I borrow books from my local Scottish library with my
> Kindle" how does it work? My Kobo just synchronises with my library
> and any borrowed books appear on the Kobo. I can do the borrowing on
> a computer or on the Kobo.
>
I log in to my library account on my computer, select a book, then send
it to my Kindle.

On 04/11/2022 10:36, Scott wrote:
> On Thu, 3 Nov 2022 22:43:25 +0000, S Viemeister
> <firstname@lastname.oc.ku> wrote:
>
>> On 03/11/2022 21:44, Chris Green wrote:
>>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
>>>>
>>>> I already have an LED lantern for that purpose (which is rechargeable
>>>> but a very large battery). I am now looking for a desk type lamp so I
>>>> can read in bed if early nights become mandated.
>>>
>>> Get a Kobo or a Kindle, much easier than a real book for reading in
>>> bed and they have long-lasting backlights. I prefer Kobo mostly
>>> because I can borrow books from my local (UK) library with it
>>> directly.
>>>
>> I borrow books from my local Scottish library with my Kindle.
>
> Is there a fine for late return :-)
>
Returning is taken care of, automatically.

S Viemeister <firstname@lastname.oc.ku> wrote:
> On 04/11/2022 10:21, Chris Green wrote:
> > S Viemeister <firstname@lastname.oc.ku> wrote:
> >> On 03/11/2022 21:44, Chris Green wrote:
> >>> Scott <newsgroups@gefion.myzen.co.uk> wrote:
> >>>>
> >>>> I already have an LED lantern for that purpose (which is rechargeable
> >>>> but a very large battery). I am now looking for a desk type lamp so I
> >>>> can read in bed if early nights become mandated.
> >>>
> >>> Get a Kobo or a Kindle, much easier than a real book for reading in
> >>> bed and they have long-lasting backlights. I prefer Kobo mostly
> >>> because I can borrow books from my local (UK) library with it
> >>> directly.
> >>>
> >> I borrow books from my local Scottish library with my Kindle.
> >
> > Yes, I think it varies from local authority to local authority. Also
> > things have got better since I bought my Kobo, I think.
> >
> > When you say "I borrow books from my local Scottish library with my
> > Kindle" how does it work? My Kobo just synchronises with my library
> > and any borrowed books appear on the Kobo. I can do the borrowing on
> > a computer or on the Kobo.
> >
> I log in to my library account on my computer, select a book, then send
> it to my Kindle.

So you can't do it all from the Kindle? Essentially it'sjust like buying
a book from Amazon.

With the Kobo it's much more integrated with the library. You can
quite easily choose and borrow books using the Kobo (no need for
computer) and the books just appear on the Kobo.

--
Chris Green
·

On 04/11/2022 11:09, Clive Arthur wrote:
> On 03/11/2022 15:42, alan_m wrote:
>> On 03/11/2022 15:32, Andy Burns wrote:
>>> alan_m wrote:
>>>
>>>
>>>> The capacity of the battery. The power bank may supply 2A @ 5V but
>>>> for only 10 minutes.
>>>
>>> Also the powerbank may quote the capacity as e.g. 20,000mAh (why not
>>> 20Ah?)
>>
>> More zeros mean a better product :) It also depends on if it's a
>> Chinese 20Ah or a real world 20Ah.  Ebay is full of batteries claimed
>> to be 4x the capacity of those same size, same technology, batteries
>> from reputable manufacturers.
>>
> The trick is that 20,000mAh is the lifetime capacity, ie keep recharging
> and using it and it'll give that amount in total till it packs up :-)
>
Also the stated capacity in mAh is only for the lithium cell ie at 3.7V.
After the DC-DC converter to bring it up to 5V when the capacity is
lower due to the stepup ratio. If only they would specify the capacity
in Wh!

On 04/11/2022 10:52, Robin wrote:
> On 04/11/2022 08:58, Andy Burns wrote:
>> Brian Gaff wrote:
>>
>>> I think officially 1 amp is the max current of standard USB sockets.
>>> Even
>>> that seems to be pushing it a bit in my view.
>>
>> What is your view on USB type C sockets allowing up to 5A at 48V ?
>
> When I saw the spec now mentioned voltages of up to 50.9V (48V + a 5%
> tolerance) I was left wondering if there were implications for touch
> voltages in domestic installations.  E.g. if a USB socket tests just
> over 50V?
>

POE Ethernet and POTS Telephones are in the region of 48V. So it is
nothing new.

On Friday, 4 November 2022 at 13:53:27 UTC, Pancho wrote:
> On 04/11/2022 10:52, Robin wrote:
> > On 04/11/2022 08:58, Andy Burns wrote:
> >> Brian Gaff wrote:
> >>
> >>> I think officially 1 amp is the max current of standard USB sockets.
> >>> Even
> >>> that seems to be pushing it a bit in my view.
> >>
> >> What is your view on USB type C sockets allowing up to 5A at 48V ?
> >
> > When I saw the spec now mentioned voltages of up to 50.9V (48V + a 5%
> > tolerance) I was left wondering if there were implications for touch
> > voltages in domestic installations. E.g. if a USB socket tests just
> > over 50V?
> >
> POE Ethernet and POTS Telephones are in the region of 48V. So it is
> nothing new.

The safety standard for computer and AV equipment is IEC62368.1 which
has a limit of 60V for "energy source class 1" sources which are considered safe
to touch.

Here is the definition:
Under normal operating conditions and abnormal operating conditions, the energy in a
class 1 source, in contact with a body part, may be detectable, but is not painful nor is it likely
to cause an injury. For fire, the energy in a class 1 source is not likely to cause ignition.
Under single fault conditions, a class 1 energy source, under contact with a body part, may
be painful, but is not likely to cause injury.
and
No safeguards are required between a class 1 energy source and an ordinary person (see
Figure 9). Consequently, a class 1 energy source may be accessible to an ordinary person.

In other words, anything up to 60V (after worst case tolerances have been applied) is fine.

There are special exceptions for telephone ringing signals and loudspeaker outputs
which allow higher voltages to be touchable that would not otherwise be permitted.
POE+ and POE++ are rated for voltages up to 57V, so they just fall within the safety
limits for touchable circuits.

John

On 04/11/2022 13:28, Chris Green wrote:
> S Viemeister <firstname@lastname.oc.ku> wrote:
>> On 04/11/2022 10:21, Chris Green wrote:
>>> When you say "I borrow books from my local Scottish library with my
>>> Kindle" how does it work? My Kobo just synchronises with my library
>>> and any borrowed books appear on the Kobo. I can do the borrowing on
>>> a computer or on the Kobo.
>>>
>> I log in to my library account on my computer, select a book, then send
>> it to my Kindle.
>
> So you can't do it all from the Kindle? Essentially it's just like buying
> a book from Amazon.
>
I haven't actually tried - I find it easier to browse books on my
computer, then request them from the library - decent keyboard, colour
book covers.

> With the Kobo it's much more integrated with the library. You can
> quite easily choose and borrow books using the Kobo (no need for
> computer) and the books just appear on the Kobo.
>

In article <jsi582Fa75dU1@mid.individual.net>,
Andy Burns <usenet@andyburns.uk> wrote:
> Also the powerbank may quote the capacity as e.g. 20,000mAh (why not 20Ah?)

Because it looks better to those who don't understand such things?

--
*If you can't see my mirrors, I'm doing my hair*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

On 04/11/2022 13:45, Andy Bennet wrote:
> On 04/11/2022 11:09, Clive Arthur wrote:
>> On 03/11/2022 15:42, alan_m wrote:
>>> On 03/11/2022 15:32, Andy Burns wrote:
>>>> alan_m wrote:
>>>>
>>>>
>>>>> The capacity of the battery. The power bank may supply 2A @ 5V but
>>>>> for only 10 minutes.
>>>>
>>>> Also the powerbank may quote the capacity as e.g. 20,000mAh (why not
>>>> 20Ah?)
>>>
>>> More zeros mean a better product :) It also depends on if it's a
>>> Chinese 20Ah or a real world 20Ah.  Ebay is full of batteries claimed
>>> to be 4x the capacity of those same size, same technology, batteries
>>> from reputable manufacturers.
>>>
>> The trick is that 20,000mAh is the lifetime capacity, ie keep
>> recharging and using it and it'll give that amount in total till it
>> packs up :-)
>>
> Also the stated capacity in mAh is only for the lithium cell ie at 3.7V.
> After the DC-DC converter to bring it up to 5V when the capacity is
> lower due to the stepup ratio. If only they would specify the capacity
> in Wh!
>
Well its a very simple sum.
Just multiply by...whatever the voltage turns out to be throughout the
discharge cycle.

--
"The most difficult subjects can be explained to the most slow witted
man if he has not formed any idea of them already; but the simplest
thing cannot be made clear to the most intelligent man if he is firmly
persuaded that he knows already, without a shadow of doubt, what is laid
before him."

- Leo Tolstoy

In article <0v58mh1t3ultmqofh091smd3ngc86k9as2@4ax.com>,
Scott <newsgroups@gefion.myzen.co.uk> wrote:
> Actually, this was my first thought. The problem is that all the 12
> volt lamps seem to be for caravans and are fixed mounting (for obvious
> reasons). I wanted a standalone lamp that can be moved around and
> maybe stored away when not needed.

Some time ago, got this from Lidl. It looks like a small version of an
outdoors flood light. Came with a desk stand, so can be pointed in most
directions. Built in battery and wall wart charger. Plenty output as a
work light. Bounce off the ceiling for general lighting of a room. Lasts
about 4 hours on a charge.

I'm sure you could buy similar from a cordless drill maker which uses the
same batteries as the drill, etc. Bound to be better value than something
made for computers.

--
*If you're not part of the solution, you're part of the precipitate *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.