Xiaomi 16000mAH Power Bank Needs Charge-only USB Cable to Work with Z3

[Humprey]

Hello!

The Xiaomi 16000mAH power bank, using its original USB cable, didn't work on my Z3. Though, to my surprise, it worked on other smartphones (have tried samsung and lenovo). So I tried my friend's power bank USB cable albeit blindly (since the Xiaomi unit worked with other phones, there should be no problem with the cable right?), and strangely, it worked!

So what gives? Later on, I found out that the other cable is a "Charge-only" cable (cannot use for data transfer). 

So why do you think exactly does this Xiaomi 16000mAH needs a charge-only USB cable in order to work with Z3 but not with other device? Also, do you think it safe to use it that way in the long run? 

Lastly find it strange that I cannot seem to find (I mean Google) any case similar to mine (I don't think I'm the only Z3 user who purchased this power bank), but I also think it is genuine (from these: https://www.youtube.com/watch?v=obYhTgzEVP8; https://www.techmesto.com/identify-fake-xiaomi-power-ba... I've already contacted the supplier about these, I think I can still send it back, but I really had it on a good deal (from Malaysia, below $25, including everything, if converted). 

What do you think? 

[Uliwooly]

I have encountered similar issues with some power banks, did you try to use Sony's usb cable? what is the output voltage on the power bank?

[Humprey]

You mean as in similar? That, on a genuine power bank, the usual data+charge cable won't work but a charge-only one would?

Yap the Sony cable won't work too. And I actually found out something about the Z3 cable included on the package with the charger during my experiment. Using current measuring apps, it seems the OEM cable don't allow the phone to draw its maximum potential current pull. When I use the charge-only cable, I'm reaching 1.5A (which is what supposed to be output by the OEM AC adapter), but using the OEM cable, I could only pull around 1A. I think this would be due to the cable quality, maybe the gauge, since AC adapters actually shorts the data pins right (which would eliminated the functional difference between data+charge and data-only)? I actually plan to make a thread about this.

And I've got another one that makes this more interesting..

I've also purchased a Sony wireless speaker SRS-BTV5, and guess what, the same happens! Using a charge+data cable won't work, but a charge-only cable would!

I guess there is a protection circuit on these Sony device that disconnects the charging (at least for this Xiaomi 16000mAH power bank), but I can't seem to imagine what would be the problem that would only be present on charge+data cable and not on a data-only cable. After all aren't power banks also do what AC charger does namely short the data pins (I just guess this since both of them is indicated "AC mode")? If this is the case, then difference between charge+data and data-only cable seem to become more non-existent!

Thanks for the response!

[Humprey]

I'm really trying to wrap my head around this (which is hard given only the facts without relevant techincal knowledge!).

What I considered facts:

1) USB cable only have 4 wires, two for power and the other two for data (presumably the inner two pins).

2) The only difference between the charge+data and charge-only cable is that the latter had its data pins shorted presumably to signal the phone that it could do a "AC mode" charging which means it could draw greater than 500mA which is not permitted on "USB mode".

3) That's presumably is what AC adapters also do (short the inner 2 pins), and that's why we have slower charging on laptop, presumably. 

4) This (shorting of 2 inner/data pins) is also how "AC mode" and "USB mode" charging is indicated/differentiated.

5) Power bank also do this data pin shorting that's why they are also indicated as "AC mode" charging

Now if the said power bank also do this (since it is indicated as "AC mode" charging), then there's shouldn't be any funtional difference between the 2 cables (but, obviously, there is)!

So we are left with the case that the said power bank do not short the data pins, (which actually makes fact 4 and/or 5 false for how are power banks indicated "AC mode"), but what functional difference then could these 2 unshorted data pins make now when we are only dealing about a power bank, meaning power supply where only the 2 power pins should be relevant?

[Humprey]

I think I also forgot to mention one important fact, that other power bank (Pineng for instance) works without any problem with my Z3 using any of the 2 types of cable I mentioned. 

So in summary other phone works on Xiaomi and other power bank works on Z3 (and speaker) on both 2 types of cable. But there's a problem between Sony devices and the Xiaomi power bank when using charge+data cable. So what could be there in either or both of them that prevents the other?!

[Uliwooly]

I have similar issues using EZO power banks, but using PNY or Sony works fine and other brands too, quite odd. 

[Humprey]

I see. I really would aapreciate if someone could tell us the technical explanation of this..

[Humprey]

i have general question about power bank, using common cable (charge+data) do they suppose to charge via AC or USB mode? 

I think it supposed to be AC mode, lest they wouldn't exceed 500mAH right? 

Now, when I tried the Xiaomi 16000mAH to other phone (Samsung Note, using charge+data cable which is what the Xiaomi OEM included cable is actually), it charges via USB mode! 

Is this some indication of fault/fake? Well it doesn't seem to me that a high capacity bank like this is supposed to only deliver 500mAH (USB mode charging)!

[Uliwooly]

@Rickard perhaps he could comment on this.

[Humprey]

I received a possible explanation to this on other site (http://forum.xda-developers.com/z3/accessories/xiaomi-16000mah-power-bank-charge-usb-t3068892#post59... he says:

>>The difference might be in "nonstandard charger" detection.

There are various methods by which some Android devices try to handle nonstandard chargers (ones that don't properly short D+/D-) more gracefully than just "no charging" or "USB only" - some work better than others, all have potential tradeoffs since, after all, it's trying to deal with an unknown "nonstandard" charger.

By "nonstandard charger" that means "Apple charger". Apple is notorious for not following standards.<<

So maybe Xiaomi 16000mAH is one of such non-standard charger (they also market it by something like it can automatically adjust output based on the device), and Sony may also have it's own way of handling these things (since other device would charge, though via USB mode only, to the said power bank using charge+data cable).

This would make it sensible now (though drifting from standard doesn't make sense to me).