Ordered unbranded EP-PG920I Qi charging pad & spotted unexpected QC issues

[Kiriakos GR]

This is my new eBay adventure.    
I did order totally unbranded EP-PG920I Qi charging pad, and received an item stamped with Samsung logos all over it.
This item weight it is 70 grams compared to original 84 grams.
In my surprise this came also with charging cable, at a total cost of 5.18EUR

While I was ready according my new buying choice, to accept an mediocre electrical performance ( something that I will test later on),  what attracted my attention right away , this is the bad job that this copycat did about the rubber pad beneath the base.

In the pictures bellow there is a demonstration of the solution which I gave and it did solved the problem.   

Speaking of product serial RF7G34827RMCIS, yes this is copycat-ed too hahaha     

[Kiriakos GR]

Today I become expert in what to expect from nameless Qi pads coming from eBay at low price.

Basically, price this is not always a warranty factor of better quality, because this is up to the seller and of how much he thinks that a product this must be sold.

Either way, this pad did not work at all in the beginning with my genuine S-View Cover Wireless EP-VG900BBEGWW
I had to start investigating and modify this so called charging pad so to work.
By removing the top rubber, phone and pad distance decreased, and pad started to get activated by working unstably.
Then removed all the top clear crystal, and even inspected the internal coil.

All those modifications helped the base to operate, but now I did spot a new problem.
This new problem it is called as heat … the closer distance from the pad to the phone this causes heat transfer from the coil of this pad to the phone case.

Supposedly there must be always a clearance distance from phone and pad so direct heat transfer this to be avoided.

Now I am aware that I have a poorly made wireless pad, from the ones called as weak ones.
Naturally I am not going to use it and I hope to receive a replacement that this will work as it should than a simple refund.

What my readers should be aware of, this is that Li-ion batteries them dislike heat, especially in summer time.
Therefore it is just not worth it, a premature damage to a good battery this worth 20~25 EUR, due a charger this worth less than six EUR.
Simple math   

Also be aware about such charging pads WITH more than 1 coils = more heat.

[Kiriakos GR]

I just made a new gadget for in-depth evaluation of 5V chargers.
This is a 0-100V DC voltmeter and also 0,001 mA - 9,999 mA (9.9A) DC current meter.
This dual meter it is a newest revision from the basic that has lesser counts.
In the box there is a PCB just hosting a female USB plug, and D+ & D- them are not disrupted.
 
Now, by removing from the fake EP-PG920I anything causing spacing between the coil and the phone, I did manage to use it for my testing purposes.
As you can see in order this Samsung Qi receiver and case, this to deliver 740mA, almost 1500mA them must be wasted due the charging pad.
And because this consumption it is constant, this is why it is advised the charging block this always to be at the max output of 2A and genuine one.
One powerless charging block, this eventually it will burst in flames and burn your home. 

Today I am considering the specific testing project as completed, Now I am going to use my new measuring gadget so to explore other truths and dark paths.   
   

[Kiriakos GR]

Today I think that my topic this needs this final addition.
Especially for the one who will ask the question as:
How one truly well build Qi circuitry this must look like? 


While Samsung trusting their own cycle of product suppliers, them be under Samsung evaluation for their products.

Other sources of Qi technology, them must use or develop similarly complicate Qi circuitry, this requiring a significant number of active electronic parts them combined with simple semiconductors.
In simple English: It is required one complex CPU this handling several parameters, and such a complex device it can not be replaced by cheap logic circuitry that most cheap Qi come with.

Bellow there are (called healthy) samples of Qi technology so you to see how they look like.   
   

[Kiriakos GR]

Recently I had the opportunity to order a sample of Qi coil this coming as branded.
I wanted to find out of why this unbranded QI charger this is such poor performer out of the box.

With my LCR I did manage to find base specifications of the unbranded coil.
Then ordered the sample.

While QI coil electrical specifications they should be made at 125 kHz, I did my at 100 kHz due LCR highest testing frequency.
Either way I got very close and I did the correct choice.

Now the very good news these are that with the new coil, my pad now working much better, even distance between smartphone and coil this improved to named specification of 6mm them be apart.

Speaking of electrical properties comparison:
.........................WE coil Named  .....  WE Coil tested   ....  No name Coil
inductance :  6.3   ............ 6.2  ...............6.6 
Q-factor :  115 ............ 197 ..........100.6
DCR :    0.04 ......... 0.05 ............ 0.06
RS:   0.048 ......... 0.022 ........0.041   

Bellow there is screen shots,  two including pulses made when the pad in not in use.
Third one this is pulses under true operating conditions.
If you have not see before Qi charger waveform, this is your golden opportunity.