Would you trust an on train USB charging point?

[Tweed]

I've just read that some ill defined rolling stock on the new TPE franchise
will sport the following:

"Every pair of seats will have power sockets and USB ports to charge
devices".

Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

[j***@gmail.com]

Post by Tweed
I've just read that some ill defined rolling stock on the new TPE franchise
"Every pair of seats will have power sockets and USB ports to charge
devices".
Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

A lot of modern planes have had USB sockets for a while. I trust them and haven't had any problems. Why would a train be any different?

[Tweed]

Post by j***@gmail.com

Post by Tweed
I've just read that some ill defined rolling stock on the new TPE franchise
"Every pair of seats will have power sockets and USB ports to charge
devices".
Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

A lot of modern planes have had USB sockets for a while. I trust them and
haven't had any problems. Why would a train be any different?

I suspect that planes are maintained to a higher standard and more care is
taken over the electronics because of what might happen if things go wrong.

[Recliner]

Post by Tweed

Post by j***@gmail.com

Post by Tweed
I've just read that some ill defined rolling stock on the new TPE franchise
"Every pair of seats will have power sockets and USB ports to charge
devices".
Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

A lot of modern planes have had USB sockets for a while. I trust them and
haven't had any problems. Why would a train be any different?

I suspect that planes are maintained to a higher standard and more care is
taken over the electronics because of what might happen if things go wrong.

All true, but also planes have a stable power supply during the flight. The
engines are running continuously and there's no reason for the voltage to
fluctuate.

I assume with trains that the USB ports are fed off batteries that are
recharged continuously from the train's hotel power supply, which will be
much less stable. The question is whether spikes in the train power supply
can get through to the USB circuits.

[ian batten]

Post by Recliner
I assume with trains that the USB ports are fed off batteries that are
recharged continuously from the train's hotel power supply

Almost nothing is powered by float-charged batteries these days: the
batteries are charged but kept out of circuit, and are switched in when the
supply fails. Devices are assumed to be able to survive the ~20ms break
(the same's true for UPSes too: the assumption is that a modern switch-mode
power supply won't cause a computer to fail if the power goes out for cycle).

I don't particularly see why a train USB socket would be any less trustworthy
than a car one. If high voltages are potentially (ho ho) applied to passenger
accessible connectors then the HSE needs to respond.

If you're nervous, charge a cheap battery pack and then use that to choose your
phone.

ian

[Anna Noyd-Dryver]

Post by Recliner

Post by Tweed

Post by j***@gmail.com

Post by Tweed
I've just read that some ill defined rolling stock on the new TPE franchise
"Every pair of seats will have power sockets and USB ports to charge
devices".
Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

A lot of modern planes have had USB sockets for a while. I trust them and
haven't had any problems. Why would a train be any different?

I suspect that planes are maintained to a higher standard and more care is
taken over the electronics because of what might happen if things go wrong.

All true, but also planes have a stable power supply during the flight. The
engines are running continuously and there's no reason for the voltage to
fluctuate.
I assume with trains that the USB ports are fed off batteries that are
recharged continuously from the train's hotel power supply, which will be
much less stable. The question is whether spikes in the train power supply
can get through to the USB circuits.

On GWR's HSTs, I think the USB sockets are powered from the 240V supply to
the sockets. Which are powered by inverters from the batteries, which in
turn are charged by the train supply.


Anna Noyd-Dryver

[Stephen Furley]

Not exactly a train, but not too different, the Oxford Tube offered both 230V and USB charging the last time I used it. Both outlets were on the same faceplate, but I'm not sure if they were far enough apart to allow both to be used at the same time. I don't know for sure, but my guess would be that each socket assembly is fed with 230 V a.c. From an on-board single phase inverter, and that the 5 V d.c. Supply for USB charging is derived from a local USB charging circuit behind each socket. BS 1363 socket outlets which also include USB charging ports, and the necessary circuitry, are widely available, and only require a 230 V supply, without a separate USB one.

I can't se why this would carry any greater risk than two conventional USB chargers plugged into two BS 1363 outlets, which electrically would be the same thing.

Modern computers, including mobile 'phones, tablets, etc. seem to be quite tolerant of poor power supplies.

[Anna Noyd-Dryver]

Post by j***@gmail.com

Post by Tweed
I've just read that some ill defined rolling stock on the new TPE franchise
"Every pair of seats will have power sockets and USB ports to charge
devices".
Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

A lot of modern planes have had USB sockets for a while. I trust them and
haven't had any problems. Why would a train be any different?

GWR's HSTs have had these in first class since the last interior refurb.
The seem to charge slower than using a mains adaptor.


Anna Noyd-Dryver

[Tim Watts]

Post by Tweed
I've just read that some ill defined rolling stock on the new TPE franchise
"Every pair of seats will have power sockets and USB ports to charge
devices".
Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

Yes - as much as a 13A power point on the same train.

[b***@aol.com]

DBS Class 66's are being fitted with them to run the tablets. So will have no choice anyhow.

[R. Mark Clayton]

Post by Tim Watts

Post by Tweed
I've just read that some ill defined rolling stock on the new TPE franchise
"Every pair of seats will have power sockets and USB ports to charge
devices".
Leaving aside the fact that a USB socket is likely to disintegrate after a
bit of use or be bunged up with chewing gum etc., would you really trust
your expensive smart phone's charging circuit to what might come out of
such a socket under fault conditions? At least with a mains socket you have
a power supply to iron out the spikes etc, and to take the fatal hit if
necessary.

Yes - as much as a 13A power point on the same train.

One would plug in a 110 = 250V 50/60Hz charge into a mains socket - this should deal with just about anything likely properly come out of the socket and smooth out any spikes and filter noise. Even if it fails, it should protect the valuable phone from damage and then you can buy a replacement for around a fiver instead of £500.