Problems with mobile phone chargers on Class 80x trains

[gallafent]

moderator note, split from this thread:

Strange wiring on an Azuma 801 228 | RailUK Forums (railforums.co.uk)

in my experience it's impossible to use my iPhone if it's plugged into a charger on one of these, some sort of EM interference makes the touch screen completely glitchy and unusable … I've never experienced this effect on any other train (or car etc.), but it was consistently the case on the GWR 80xs when I used them frequently.

 

[najaB]

Good luck with that on an 80x … in my experience it's impossible to use my iPhone if it's plugged into a charger on one of these, some sort of EM interference makes the touch screen completely glitchy and unusable … I've never experienced this effect on any other train (or car etc.), but it was consistently the case on the GWR 80xs when I used them frequently.

If it only happened while it was connected to the charger and was fine when it wasn't then I strongly suspect the charger was at fault! It could well be that the AC supply wasn't a pure-enough sine wave for the charger, or the peak voltage was was just low enough that it kept trying to switch between 120v and 230v operation.

Switch mode power supplies vary quite a bit in quality, and the ones at the lower end of the spectrum can have issues with anything other than the cleanest sine wave input.

 

[43096]

If it only happened while it was connected to the charger and was fine when it wasn't then I strongly suspect the charger was at fault! It could well be that the AC supply wasn't a pure-enough sine wave for the charger, or the peak voltage was was just low enough that it kept trying to switch between 120v and 230v operation.

Switch mode power supplies vary quite a bit in quality, and the ones at the lower end of the spectrum can have issues with anything other than the cleanest sine wave input.

It can’t be an individual charger as there’s loads of people who reported it - it only occurs when the train is under 25kV, not on diesel in my experience.

 

[IanXC]

If it only happened while it was connected to the charger and was fine when it wasn't then I strongly suspect the charger was at fault! It could well be that the AC supply wasn't a pure-enough sine wave for the charger, or the peak voltage was was just low enough that it kept trying to switch between 120v and 230v operation.

Switch mode power supplies vary quite a bit in quality, and the ones at the lower end of the spectrum can have issues with anything other than the cleanest sine wave input.

Long standing issue with 80x. It's a very dirty supply I'm told. I would never attempt to use my phone while it's charging on an 80x, it's simply infuriating.

 

[gallafent]

Long standing issue with 80x. It's a very dirty supply I'm told. I would never attempt to use my phone while it's charging on an 80x, it's simply infuriating.

Good to know it's not just me. Should plug an oscilloscope in at some point to see what it looks like. I wonder if there were specifications for this in the contract. And if so, whether (a) they were bad specifications or (b) they are not being met — it must be one or the other, clearly!

 

[najaB]

It can’t be an individual charger as there’s loads of people who reported it

Each of whom has an individual charger. Don't forget, half of all chargers are of below average quality.

 

[IanXC]

Each of whom has an individual charger. Don't forget, half of all chargers are of below average quality.

It's definitely an issue with the units; it is known and accepted by the operators.

 

[najaB]

It's definitely an issue with the units; it is known and accepted by the operators.

I know it's seen commonly but it's only an issue with the units if the power they're producing doesn't meet UK tolerances. There are a *lot* of very poor quality switch mode power supplies out there!

As noted above, it would be interesting to see an oscilloscope trace of the AC power supplied.

 

[gallafent]

it would be interesting to see an oscilloscope trace of the AC power supplied.

(A spectrum analysis might be useful too …)

it's only an issue with the units if the power they're producing doesn't meet UK tolerances.

Any chance of a link to somewhere which specifies these? I mean more detail than just the “50Hz+-1% sine wave at 230V-6%+10%” basics, more about how far from a sine wave they are allowed to diverge, acceptable harmonic content, etc., … at that point it would be possible to determine whether or not the supply on the 80x is acceptable …

(edit): Ah, BS EN 50160:2010 looks like the ticket. Now to decipher it. I expect someone on these forums has appropriate testgear for measuring the THD and so on as well as just the basics (I don't, and don't currently have the spare ~£500 available to buy an instrument, and £218 to buy the standard, just for this interesting but non-core project!) …

There's an interesting summary document that outlines the key requirements of the standard, available at https://copperalliance.org.uk/uploads/2018/03/542-standard-en-50160-voltage-characteristics-in.pdf (not quoted here since it's big, and for copyright reasons!), so with an appropriate meter / logger it should be straightforward to determine whether or not the 80x's supply is in spec (without forking out for the standard!). Depending on the way in which it is out of spec, it might be possible to correct it with a relatively minor intervention (filtering …), one would hope.

 

[najaB]

Depending on the way in which it is out of spec, it might be possible to correct it with a relatively minor intervention (filtering …), one would hope.

I suspect so. Hopefully they're not rectifying the 25kV AC and then inverting it again because that could be expensive to fix.

 

[ABB125]

I suspect so. Hopefully they're not rectifying the 25kV AC and then inverting it again because that could be expensive to fix.

Where else would the power come from, if not the OHLE?

I'm guessing that rectification isn't the problem, rather the inversion back to AC from whatever DC voltage they're using?

 

[najaB]

Where else would the power come from, if not the OHLE?

The energy would be coming from the OHLE, yes, but there's more than one way to get 230V. It could be a straight old fashioned iron-core transformer, they could drive a motor-alternator, rectification and inversion - hell, if they feel like playing with (literal) fire it could be a capacitive dropper!

 

[ABB125]

it could be a capacitive dropper!

That's a new one for me - I wonder why it isn't covered in first year engineering degree electrical modules...

 

[najaB]

That's a new one for me - I wonder why it isn't covered in first year engineering degree electrical modules...

So that they have people left alive for second year!

 

[ABB125]

So that they have people left alive for second year!

Perish the thought of actually doing something practical, especially last year...

Anyway, back on topic!

 

[D365]

Long standing issue with 80x. It's a very dirty supply I'm told. I would never attempt to use my phone while it's charging on an 80x, it's simply infuriating.

A vast majority of people that I have talked to (both in and out of the industry) have confirmed that this is their experience also.

 

[Skymonster]

Had the same problem on a United Airlines 787 - iThing totally unusable when plugged in.

 

[_toommm_]

It knackered my MacBook Pro when I was on a TPE 802. Made the Force Touch trackpad unusable and made the trackpad I was using multi touch gestures instead of just the one finger.

 

[dgl]

I used to have a similar problem with the touchscreen on my laptop if I connected it to my Panasonic CD/Radio without the grounded supply for the laptop connected (just running off the battery).

I would guess the supply is potentially running off an inverter mainly to cope with the varying voltages of the OLE as I would guess doing that would be lighter than having an automatically adjusting variac.
I wonder if the issues are either said inverter outputs modified sine wave or there's some kind of earthing issue that effects the RFI filtering.

A dedicated electronics forum is probably the best place to ask, e.g. the vintage radio forums.

 

[richw]

I’ve had the same issue on GWR Hsts when using a cheap replacement cable from a well known retailer that sells items for one pound. No issues though when I’ve been using a genuine cable. I’ve found it usable when using 801/802 but doesn’t charge the battery, just keeps it at the same percentage!

 

[dosxuk]

iDevices and Mac laptops are notorious for dumping fairly high amounts of leakage current, even with genuine chargers, which will cause issues with the touch screens / track pads. I've seen this on clean (if slightly higher voltage than desired, but still within spec) power supplies, especially if you happen to be in contact with an earthed object. I can't remember the exact scenario, but I've also seen another piece of equipment crash after a charging iDevice was placed on top.

I suspect that it's a rough power supply on the train and the rough charging design on the phone, is making a situation where both sides are independently within spec, but fall out of spec when used together.

 

[uvarvu]

I'm having deja vu on this topic, wasn't this discussed elsewhere on these forums? One of the reasons I ask is that I swear there was a picture of a unit which had some sort of device fitted to mitigate the problem.

 

[gallafent]

iDevices and Mac laptops are notorious

Ah, now this is interesting. I do also have other non-Apple devices with touch screens that I can try (with the same charger(s)) to see whether or not they misbehave. That would be an interesting datapoint. Not quite sure when I'll next actually be on an 80x, but I'll try to remember to have at least one with me.

 

[Nym]

When I was doing testing on 802s there were quite a few issues with the at seat supply I was using for my accompanying laptops, ran the power brick a lot hotter than it should do, my suspicion being it had quality issues that were overworking the filter.
When I moved to use our instrumentation supply from a battery supply on a true sine wave converter, the issue went away and the temperature on the power bricks dropped.

If I ever travel on one personally (doesn't happen often) I might slip my picoscope onto it and see what's what.

 

[Bald Rick]

I'm having deja vu on this topic, wasn't this discussed elsewhere on these forums? One of the reasons I ask is that I swear there was a picture of a unit which had some sort of device fitted to mitigate the problem.

There have been at least two threads on the subject. It’s not just 80x trains, or even just trains. (It’s also my office!)

 

[JN114]

I’ve experienced many times with iPhone in locations where I’d expect the power supply to be “poor” - including on IETs

I’ve always found taking the handset out of its case, and using it “naked” while charging completely cures the problem. As I understand the ground on an iPhone is around the edge of the phone, and the poor power supply coupled with poor grounding through people’s typically non-conductive cases is recipe for poor touchscreen responsiveness.

 

[lkpridgeon]

I've experienced it with chargers ranging from a cheap Poundland special up to a ThinkPad power brick. My experience with charging my phone and Nintendo switch is the power cuts in and out quite regularly (Sony & Samsung) no matter the charger. And can anecdotally say my ThinkPad charger was running hotter than usual.

There must be something going on.

 

[Bletchleyite]

Are they inverter-fed? Cheap inverters tend to produce very dirty, stepped AC which could be causing the issue. I plugged a CRT TV into one once and it made a right mess of the scanning which was clearly depending on a clean AC curve to work nicely.

Apple kit is very sensitive over earthing, certainly, I've had the issues above with cheap chargers in normal mains too. I'm not sure why as other manufacturers' kit isn't.

 

[_toommm_]

I've experienced it with chargers ranging from a cheap Poundland special up to a ThinkPad power brick. My experience with charging my phone and Nintendo switch is the power cuts in and out quite regularly (Sony & Samsung) no matter the charger. And can anecdotally say my ThinkPad charger was running hotter than usual.

There must be something going on.

The way the power feeds is definitely different to the previous electric trains (MK4/91s). You know you’re going into a neutral section because the power doesn’t continue to be fed to the sockets.

 

[swt_passenger]

I'm having deja vu on this topic, wasn't this discussed elsewhere on these forums? One of the reasons I ask is that I swear there was a picture of a unit which had some sort of device fitted to mitigate the problem.

Here’s a previous thread from 2019 on the same subject:

iPhone touchscreens on Class 800/801

Very odd problem. A friend reported on a class 800 on LNER that his iPhone's did not respond to touchscreen input when plugged into the power on the train. On a GWR Class 800 same problem with my friends iPhone. Anyone else noticed this?

www.railforums.co.uk

I can’t find any reference there to a mitigation device, but it could be my search terms aren’t finding all the threads…