Author Topic: Dodgy USB Chargers  (Read 5657 times)

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Offline labnet

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Dodgy USB Chargers
« on: September 17, 2018, 03:53:33 am »
Thought I would start a thread for dodgy USB chargers.
You know, you buy the 'genuine' apple USB charger only to find its a chinese knockoff.
I remember once buying a 12W apple charger and the 240v head plastic was slightly different to the case body. I took it apart, and lo and behold, craptastic creepages. The ebay seller replaces it. I take the replacement apart, and boom, different design and at least an attempt at creepage control but again a copy.
I down vote them, and oh boy are they upset. No amount of explaining would convince them that what they were doing was illegal and potentially dangerous... no.. it was all about the one star review.

My latest problem is with a Volans unit bought from retail in Australia. The end plate takes the full force of the PCB when unplugging the fig-8 power cable. The end plate has popped off on my unit, pulling the unrestrained PCB with it and exposing 240v direct to consumer in the process.

Maybe Dave should go buy a whole heap of 'Genuine' chargers from ebay and check them out.
 

Offline Raj

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Re: Dodgy USB Chargers
« Reply #1 on: September 17, 2018, 04:02:42 am »
Brands aren't no better. My genuine made in India, motorola usb-c charger has started to give bearable amount of shock after 3 years of use (touching the shielding portion of the charger plug is enough to give you a shock).To make it worse, the whole phone's body is conductive.

My hp printer's adapter, lacks a ground pin.touching any metal portion like usb port gives you a shock, Until you connect it to a grounded computer.
My samsung monitor does the same thing too,if you touch vga plug,unless again, its connected to a computer.

None of them trigger mains GFI.
You know, when devices start to give you shock, it is really a good method to brain wash yourself to not use them.


Meanwhile, My zte charger and motorola charger, age 6, works fine but both are rated for 600mA.

They Really don't make things like they used to.
« Last Edit: September 17, 2018, 04:07:19 am by Raj »
 

Online blueskull

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Re: Dodgy USB Chargers
« Reply #2 on: September 17, 2018, 04:10:37 am »
My genuine made in India, motorola usb-c charger has started to give bearable amount of shock after 3 years of use (touching the shielding portion of the charger plug is enough to give you a shock).To make it worse, the whole phone's body is conductive.

That's called Y capacitor. To control EMI, a hihg voltage, guaranteed not to fail or only fail open, capacitor is placed between primary and secondary to shunt transformer coupled noise.
Cheaper chargers use hard switch flyback, which requires higher Y cap capacitance, hence more leakage. To make things worse, the leakage current doubles in 220V/240V countries compared with US/Japan.

If you hate leakage, go for a medical power supply. They are designed with goal of reducing leakage current. 1mA leakage to your hand when you hold your phone is not a big deal. 1mA leakage to your heart muscle in an open chest surgery can kill you.
 

Offline Raj

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Re: Dodgy USB Chargers
« Reply #3 on: September 17, 2018, 05:05:03 am »
If you hate leakage, go for a medical power supply. They are designed with goal of reducing leakage current. 1mA leakage to your hand when you hold your phone is not a big deal. 1mA leakage to your heart muscle in an open chest surgery can kill you.

True, electricity is way worse when it has a direct path through flesh. I've given myself shock from 9v battery by accidentally pricking the wire into my finger

but it's kinds strange,Hp printer has a ground pin, which is not connected anywhere at all.Why didn't they connect it to reduce the shock? Plus, Motorola charger  didn't give a shock when it was brand new.
 

Online wraper

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Re: Dodgy USB Chargers
« Reply #4 on: September 17, 2018, 06:43:58 am »
If you hate leakage, go for a medical power supply. They are designed with goal of reducing leakage current. 1mA leakage to your hand when you hold your phone is not a big deal. 1mA leakage to your heart muscle in an open chest surgery can kill you.

True, electricity is way worse when it has a direct path through flesh. I've given myself shock from 9v battery by accidentally pricking the wire into my finger

but it's kinds strange,Hp printer has a ground pin, which is not connected anywhere at all.Why didn't they connect it to reduce the shock? Plus, Motorola charger  didn't give a shock when it was brand new.
Because it's double insulated and does not need ground pin for operating safely. Then think about charger plug size and where it will be plugged, don't tell me fairy tales about all sockets in India to be grounded. Also without Y cap, touchscreen of the phone attached usually will stop operating properly, even if there was no purpose of passing EMC test.
Quote
Plus, Motorola charger  didn't give a shock when it was brand new.
:palm: Then something has changed in how you used it. I guess at that time there were no metal objects with a path to ground anywhere around. Therefore there was no path for current to flow and you did not feel anything.
« Last Edit: September 17, 2018, 11:27:46 pm by wraper »
 

Offline labnet

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Re: Dodgy USB Chargers
« Reply #5 on: September 17, 2018, 10:21:28 pm »
What I find interesting, at least in the Australian context, is that as a business, I have to make sure I pass RCM. In fact we pulled a product because re-certifying ($10k+) was going to cost more than the profit than we made on that particular product.
Yet, people can import products without RCM marks, and I'm sure most ebay sellers are bulk importing from China and reselling their gear without getting the local certifications.
So either certification is a waste of time (because death rates/interference haven't gone up from the use of all this un-certified gear so we should scrap it), or the government should be doing a lot more policing of this area to make a level playing field for everyone.
 

Offline Raj

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Re: Dodgy USB Chargers
« Reply #6 on: September 18, 2018, 04:47:18 am »
If you hate leakage, go for a medical power supply. They are designed with goal of reducing leakage current. 1mA leakage to your hand when you hold your phone is not a big deal. 1mA leakage to your heart muscle in an open chest surgery can kill you.

True, electricity is way worse when it has a direct path through flesh. I've given myself shock from 9v battery by accidentally pricking the wire into my finger

but it's kinds strange,Hp printer has a ground pin, which is not connected anywhere at all.Why didn't they connect it to reduce the shock? Plus, Motorola charger  didn't give a shock when it was brand new.
Because it's double insulated and does not need ground pin for operating safely. Then think about charger plug size and where it will be plugged, don't tell me fairy tales about all sockets in India to be grounded. Also without Y cap, touchscreen of the phone attached usually will stop operating properly, even if there was no purpose of passing EMC test.
Quote
Plus, Motorola charger  didn't give a shock when it was brand new.
:palm: Then something has changed in how you used it. I guess at that time there were no metal objects with a path to ground anywhere around. Therefore there was no path for current to flow and you did not feel anything.

The phone's body is metallic, so I would have noticed. Now I can't touch the phone while charging. Also, this means, it ain't double insulated.
Also,nothing was done to the charger except for using it to charge the phone.So natural degradation pretty much.
The touchscreen still works.
I don't care since the phone was S#!t anyways, except for the battery life, camera and best kind of card tray.

And about grounding India,My house has grounding ever since it was built. But it's becoming a must have since even corsair's (other companies too) computer power-supply electrifies the chassis of a computer, if ground is missing.My cousin had to get his house electricity grounded because of that, when he bought his first PC.

Attached-photo of a goofy plug for hp printer's adapter.Notice how the wire contains only 2 conductors and no ground point at adapter side. Funny that they spent an extra buck on the metal of plug's ground pin.
« Last Edit: September 18, 2018, 05:12:16 am by Raj »
 

Online wraper

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Re: Dodgy USB Chargers
« Reply #7 on: September 18, 2018, 07:40:38 am »
The phone's body is metallic, so I would have noticed.
:palm: Do you understand that current won't flow unless there is current path? You can hold line wire under voltage and not feel anything if you don't touch anything else conductive (say standing bare foot on wet floor).
Quote
Also, this means, it ain't double insulated.
So you don't even know what double insulated means.
« Last Edit: September 18, 2018, 07:43:18 am by wraper »
 

Offline Raj

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Re: Dodgy USB Chargers
« Reply #8 on: September 18, 2018, 08:44:39 am »
The phone's body is metallic, so I would have noticed.
:palm: Do you understand that current won't flow unless there is current path? You can hold line wire under voltage and not feel anything if you don't touch anything else conductive (say standing bare foot on wet floor).
Quote
Also, this means, it ain't double insulated.
So you don't even know what double insulated means.

Double insulated means, every part of the circuit has 2 layers of insulation as separation from outside. Moto z play isn't double insulated. The whole body of the phone is connected to usb shielding and the ground of the whole circuitry inside.

Also, charger was double insulated but it now has failed.

You can feel it zapping you even with rubber flipflops on.And surely if it was made like this from day one, it would have zapped my in 2 years of heavy use

The fact remains that it has started to zap me and that wasn't the reason why I stopped using it.(I could have replaced the charger and continued)

Also, there is 35 volts AC, from usb shielding to the ground with max current of 5uA
« Last Edit: September 18, 2018, 09:12:39 am by Raj »
 

Online wraper

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Re: Dodgy USB Chargers
« Reply #9 on: September 18, 2018, 09:10:52 am »
Double insulated means, every part of the circuit has 2 layers of insulation as separation from outside. Moto z play isn't double insulated. The whole body of the phone is connected to usb shielding and the ground of the whole circuitry inside. This means, charger was double insulated but it now has failed.
Yep, you completely don't understand what it means. Sure phone is not double insulated, the charger is.  https://en.wikipedia.org/wiki/Appliance_classes#Class_II
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The basic requirement is that no single failure can result in dangerous voltage becoming exposed so that it might cause an electric shock and that this is achieved without relying on an earthed metal casing.

Quote
Also, there is 35 volts AC, from usb shielding to the ground with max current of 5uA
LOL, and you call it failed insulation?  :palm:. With Y cap between primary and secondary side you normally can measure half of the mains voltage and up to about 0.3mA leakage current. And it's completely normal and within spec.
« Last Edit: September 18, 2018, 09:13:10 am by wraper »
 

Offline stj

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Re: Dodgy USB Chargers
« Reply #10 on: September 19, 2018, 06:51:11 pm »
so-called "safety caps" can and do go leaky with age - so do MOV's
if your getting more of a tingle than when it was new then the cap is probably starting to break down.
 

Online wraper

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Re: Dodgy USB Chargers
« Reply #11 on: September 19, 2018, 07:09:24 pm »
so-called "safety caps" can and do go leaky with age - so do MOV's
if your getting more of a tingle than when it was new then the cap is probably starting to break down.
Excuse me but Y caps don't get leaky unless something extraordinary happens, and such product gets recalled. Also comparing them with MOVs is ridiculous, there is a good reason why MOV clamping voltage goes down with time.
Quote
if your getting more of a tingle than when it was new then the cap is probably starting to break down
:palm: You'll get tingle from almost anything if there is Y cap and current path through you. Also you may feel weird feeling when moving your fingers over metal surface even if there is no current path. Especially noticeable on laptops with metal case.
 

Offline stj

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Re: Dodgy USB Chargers
« Reply #12 on: September 19, 2018, 08:28:55 pm »
i'v been in the repair industry for a long time and replaced more than a few safety-rated caps that had gone leaky or just plain split in half and burned.
it may be rare, but it happens.

here is something to dwell on.
if a cap is rated at 1KV and is sitting on a 240v line, how many times a day is it going to see over the rated voltage for a fraction of a cycle?
i'm pretty sure test meters rated for mains must be spec'ed to survive 6KV spikes.
 

Online Wolfgang

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Re: Dodgy USB Chargers
« Reply #13 on: September 19, 2018, 08:32:43 pm »
Hi,

I must say, same experience. I hate them. They are unsafe, create a lot of illegal EMI and are simply junk.

To get some RFI out of my ham shack, I killed them all. See here:

https://electronicprojectsforfun.wordpress.com/power-supplies/a-quad-usb-power-supply-with-low-noise/
 

Online wraper

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Re: Dodgy USB Chargers
« Reply #14 on: September 19, 2018, 09:29:41 pm »
if a cap is rated at 1KV and is sitting on a 240v line, how many times a day is it going to see over the rated voltage for a fraction of a cycle?
i'm pretty sure test meters rated for mains must be spec'ed to survive 6KV spikes.
X capacitors sure do blow up, never seen Y cap failed. And if this happens it should be caused by something akin thunderstorm. You cannot buy Y cap rated for 1kV. For consumer electronics Y2 and sometimes Y1 capacitors are used.

« Last Edit: September 19, 2018, 09:34:03 pm by wraper »
 

Online Gyro

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Re: Dodgy USB Chargers
« Reply #15 on: September 19, 2018, 09:53:02 pm »
I came across a couple of Rifa MP Y caps in an old HP3310A Function generator after the X one did its characteristic meltdown. They hadn't failed but were showing the same characteristic package moisture cracking. Needless to say, they got retired!

Those are the worst exception though. You're unlikely to come across anything other than Ceramic Y caps these days, certainly in new stuff.
Chris

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Online wraper

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Re: Dodgy USB Chargers
« Reply #16 on: September 19, 2018, 11:01:49 pm »
I came across a couple of Rifa MP Y caps in an old HP3310A Function generator after the X one did its characteristic meltdown. They hadn't failed but were showing the same characteristic package moisture cracking. Needless to say, they got retired!

Those are the worst exception though. You're unlikely to come across anything other than Ceramic Y caps these days, certainly in new stuff.
Yep, those are exceptional junk. Although I dod not came across those caps in Y variant. Normally Y caps are ceramic.
 

Offline Raj

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Re: Dodgy USB Chargers
« Reply #17 on: September 21, 2018, 03:49:20 pm »
Well I did had a problem distinguishing purpose from method

The company should have thought of what if scenarios and should have designed the charger differently so as to not allow any leakages considering that the user is definitely gonna come in contact to it.

Btw,No other phone charger, including those using Y caps that I've seen so far leaks current so high the one can feel it. Infact I trust my reputation on many of them. I often insert sony charges into my creations.
« Last Edit: September 21, 2018, 03:51:13 pm by Raj »
 

Online wraper

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Re: Dodgy USB Chargers
« Reply #18 on: September 21, 2018, 06:28:23 pm »
Btw,No other phone charger, including those using Y caps that I've seen so far leaks current so high the one can feel it. Infact I trust my reputation on many of them. I often insert sony charges into my creations.
Excuse me but 5uA leakage current is nothing. You'd have a very hard time finding a charger with so little leakage current. I think it does not even have Y cap at all, and all leakage happens through capacitance between windings in transformer. Or you did your measurements wrong.

 :palm: Yeah, and your measurements completely contradict your claims about feeling current leakage. And don't forget that all leakage through Y cap happens as AC through capacitance. It has nothing to do with quality of insulation.
 

Offline stj

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Re: Dodgy USB Chargers
« Reply #19 on: September 22, 2018, 10:19:43 am »
and inclusion of said cap violates the "double insulated" claim.
it's "insulated" (sort of) by a single dialectric layer.
 

Online Gyro

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Re: Dodgy USB Chargers
« Reply #20 on: September 22, 2018, 10:39:37 am »
and inclusion of said cap violates the "double insulated" claim.
it's "insulated" (sort of) by a single dialectric layer.

It's done by agency approved withstand voltage rating. You would specify Y1 cap (8kV withstand) for Class II. It's the same situation for the regulation  feedback optoisolator....

In Grounded chassis applications you typically use Y2 caps (~4kV), In Class II double insulated you use Y1 (8kV)

The same situation with the PCB itself. For grounded chassis, mains to chassis clearance is 4mm, for Class II it's 8mm. Effectively two 4mm insulation gaps side by side. They don't have to be physical barriers (as long as the conductors can't move!).
« Last Edit: September 22, 2018, 11:22:06 am by Gyro »
Chris

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Online TurboTom

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Re: Dodgy USB Chargers
« Reply #21 on: September 22, 2018, 12:45:46 pm »
Well, this one is a good joke by itself. And you probably need a good insurance if you're going to use it. Wait a moment, got it as a feebie with the branding of a major international -- you guess it -- insurance company!  >:D


So far, so good...



No glue whatsoever, the plate with the wall plug prongs is just snapped in and it's so wobbly a five-year old could open it  :o



Admittedly, it's tiny but do these components have to be cramped inside like this?



Isolation clearance? What is it? It would be generous to say it's one millimeter. And even that's sprinkled with flux!



Here's the one I like most -- a genuine press fit between the input smoothing electrolytic and the USB shielding can. Probably cannot get any better than this!



If this company is still in business? They've got to have a good insurance...  :P

Obviously, I never plugged that one in. Maybe I'll check it with an insulation tester, just for fun. At least the micro USB cable that was included is useful since it includes the data lines unlike some of these super-cheap charging only cables...
« Last Edit: September 22, 2018, 12:49:05 pm by TurboTom »
 

Online Gyro

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Re: Dodgy USB Chargers
« Reply #22 on: September 22, 2018, 01:10:48 pm »
That is by far the worst I have seen in a long time! It's impossible to quantify any primary-secondary isolation gap.


The fact that they are a German based Insurance company is the topping on the cake! .... Oh no, sorry, the dry jointed negative lead on the output capacitor is probably in the running too.  :palm:


P.S. I am sorely tempted to sent Allianz a link to their blatant breach of CE regulations, and hence, EU law! [Edit: @TurboTom, how long ago did you get that thing? Any history? Presumably they've handed out these lethal items by the bucket load!]
« Last Edit: September 22, 2018, 01:25:56 pm by Gyro »
Chris

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Online wraper

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Re: Dodgy USB Chargers
« Reply #23 on: September 22, 2018, 01:14:03 pm »
At least the micro USB cable that was included is useful since it includes the data lines unlike some of these super-cheap charging only cables...
I would not consider it as anything good. Most likely it has hair thin strands in the wires which have so much resistance that phone will limit charging current because of a huge voltage drop. Also don't expect it to be shielded.
 

Online TurboTom

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Re: Dodgy USB Chargers
« Reply #24 on: September 22, 2018, 01:49:33 pm »
My daughter won it at a tombola at this year's summer festivities at her school. All the items given away there had been donated by parents. I remember there were many of the USB power adapters. Only recently I got it in my hands again and opened it. I guess I better phone the school on monday and warn them about the adapters...

I don't know when or if they had been actually distributed by Allianz or if they just stayed in some employee's home who eventually donated them to the tombola.

Cheers,
Thomas
 
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