On 18/10/2022 18:32, bob prohaska wrote:

It turns out my Pi2 problems were yet another dying power supply.

I can easily splice the old power cord onto a new wallwart, but
wonder if it's possible to use a USB C adapter that might remain
useful after the Pi2 is obsolete.

AIUI USB C power supplies can deliver up to 20 volts after negotiating
with the load. Less clear is how the negotiating is done and what happens
if a C power supply is connected to a Pi2 which can't negotiate.

Anybody tried it?

Thanks for reading,

bob prohaska

Bob,

I've been going for power supplies which say they are 5V, such as the official RPi-4 USB-C ones. No mention there of having the higher-voltage options. Beware of xPhone "compatible" ones.

--
Cheers,
David
Web: https://www.satsignal.eu

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It turns out my Pi2 problems were yet another dying power supply.

I can easily splice the old power cord onto a new wallwart, but
wonder if it's possible to use a USB C adapter that might remain
useful after the Pi2 is obsolete.

AIUI USB C power supplies can deliver up to 20 volts after negotiating
with the load. Less clear is how the negotiating is done and what happens
if a C power supply is connected to a Pi2 which can't negotiate.

Anybody tried it?

Thanks for reading,

bob prohaska

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In article <9eb76f395a.DaveMeUK@BeagleBoard-xM>, David Higton <dave@davehigton.me.uk> wrote:

A USB charger is not intended to run 24/365.

yes they are.

Depending on how much you
run your Pi2, you may find you're better off with a proper power supply.

usb chargers are proper, except perhaps noname junk that's best avoided.

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On Tue, 18 Oct 2022 15:29:08 -0400, nospam wrote:

In article <9eb76f395a.DaveMeUK@BeagleBoard-xM>, David Higton <dave@davehigton.me.uk> wrote:

A USB charger is not intended to run 24/365.

There are actually three classes of 'PSU's, all designed for different use cases:

1) *battery charger*, which is designed for intermittent use, typically
it is only in use for a small fraction of its duty cycle. That's
because its job is to top off the battery it's attached to and then
set its 'charge complete' indicator and shut down.
It is NOT designed for continuous operation.

2) *PSU*, USB or not. These are designed to run 24/7, but offer no
protection against mains failure

3) 'uninterruptable power supply', which is designed to keep its load
powered regardless of interruptions of its power source, though the
length of time it can provide power will be specified. Longer costs
more.

It pays to think about which of those classes you actually want before installing anything: picking the wrong type for your application is likely
to be unsatisfactory. And be careful to over-specify rather then under-
specify your power source as well as considering its use case because that
will extend its life.

Depending on how much you run your Pi2, you may find you're better off
with a proper power supply.

Spot on. There's a fourth case too: the 'piece of crap'. Avoid at all
costs.



--

Martin | martin at
Gregorie | gregorie dot org

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bob prohaska <bp@www.zefox.net> wrote:

It turns out my Pi2 problems were yet another dying power supply.

I can easily splice the old power cord onto a new wallwart, but
wonder if it's possible to use a USB C adapter that might remain
useful after the Pi2 is obsolete.

AIUI USB C power supplies can deliver up to 20 volts after negotiating
with the load. Less clear is how the negotiating is done and what happens
if a C power supply is connected to a Pi2 which can't negotiate.

The USB-C power interface is a total can of worms IMHO, it is far, far
too complex and the chances of buying a supply that implements it
completely or properly are minimal.

Anything that uses much more than the extra current available at 5
volts probably needs to be specific to the device manufacturer to be
safe.

--
Chris Green
·

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bob prohaska <bp@www.zefox.net> wrote:

It turns out my Pi2 problems were yet another dying power supply.

Just get the effing official power supply already. Maybe it's $2 more but
that is definitely worth it.

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Chris Green wrote:

The USB-C power interface is a total can of worms IMHO, it is far, far
too complex and the chances of buying a supply that implements it
completely or properly are minimal.

what about the micro-USB?

Also what about using only the +5V and negative (red/black) - what kind of negotiations are you talking about?!

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On Tue, 18 Oct 2022 21:10:51 +0100
Chris Green <cl@isbd.net> wrote:

The USB-C power interface is a total can of worms IMHO, it is far, far
too complex and the chances of buying a supply that implements it
completely or properly are minimal.

The chip makers are all over this - there will undoubtedly be a few
bad ones but they should fall out of use pretty quickly or get fixed. WiFi
and Bluetooth are *way* more complex but all a manufacturer has to do to
get it right is use a decent chip.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

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Deloptes <deloptes@gmail.com> wrote:

Chris Green wrote:

The USB-C power interface is a total can of worms IMHO, it is far, far
too complex and the chances of buying a supply that implements it completely or properly are minimal.

what about the micro-USB?

The 'old' micro-USB is fairly straightforward, usually. I think there
are some possible extras but basically the only real 'extra' is the availability of more current from some PSUs.

Also what about using only the +5V and negative (red/black) - what kind of negotiations are you talking about?!

On USB-C the source and client can 'negotiate' all sorts of changes to
the basic 5 volt supply, it can be negotiated up to 12 volts or even
20 volts. The 'negotiation' comprises signals on the other pins of
the connector so (as far as I understand it) if you only connect to
the 0v and +ve supply pins you should only ever get 5 volts.

--
Chris Green
·

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On Tue, 18 Oct 2022 20:06:07 -0000 (UTC), Martin Gregorie <martin@mydomain.invalid> wrote:

There are actually three classes of 'PSU's, all designed for different use >cases:

1) *battery charger*, which is designed for intermittent use, typically
it is only in use for a small fraction of its duty cycle. That's
because its job is to top off the battery it's attached to and then
set its 'charge complete' indicator and shut down.
It is NOT designed for continuous operation.

Many of these can negotiate with the device they are charging to
supply a higher voltage / current.

2) *PSU*, USB or not. These are designed to run 24/7, but offer no
protection against mains failure

They are supposed to deliver a fixed voltage. No negotiation.
The device determines how much current it will pull at any
moment, up to a PSU specific maximum current.
--
Kees Nuyt

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Chris Green wrote:

On USB-C the source and client can 'negotiate' all sorts of changes to
the basic 5 volt supply, it can be negotiated up to 12 volts or even
20 volts.

Latest USB PD spec allows 48V @ 5A

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On Fri, 21 Oct 2022 08:43:19 +0100
Andy Burns <usenet@andyburns.uk> wrote:

Latest USB PD spec allows 48V @ 5A

Nice cheap, warm cables.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

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