[Nexus 5X General] nikozzzzzz:
Intro

I do not take any responsibility for any damaged, bricked, burned devices or electric shock caused by your doing. You need basic knowledge of electicity before doing something.

I got my N5X a few weeks ago, and unfortunately found out that all my powerbanks are useless - N5X takes about 400-500 mAh from the battery pack ( via a normal USB -> TypeC cable) and it is not even enough to keep the battery charging - if the screen is on, the phonejust slooooowly discharges

Ideas

So I had a few Ideas of how to fix the problem:

1) Buy a compatible USB Type-C powerpack on Amazon/Aliexpress, wait for it for like 2 month ( I live neither in USA nor in China ) and hope that Fast Charging, oh wait, at least, normal charging will work.

2) Try out all powerpacks I can find in hope that some will have a compatible DATA+/- chip/resistor/shortcircuit combination.

3) Read USB Type-C charging specs and find out what ICs support the so called "Fast charging" like the Qualcomm QuickCharge ( remember, you need a special IC doing voltage negotiation between charger and phone )

Thoughts

Number 1 was not a solution for me because I have LOTS of 18650 lithium batteries ( and also some LiPos my friend gave me) and paying $50 for a compatible battery pack is OMGTOOMUCH :laugh:

Nubmer 2 was a partial solution for me ( and I did find A LOT of powerpacks and tried them out, no result )

Number 3 made me really sad, after reading the specs I found out that you really do need an IC, because Type-C has a special data pin for power negotiations, and it has a special protocol.

Solution

Turned out to be simpler than I thought.

Logic behind my solution: We got a phone that has a special pin in Type-C usb port, that waits for the charger to tell " heeey I am strong,I am legit made by LG, you can take up to 3A from me".

But it is difficult to buy 2-3 additional original chargers ( 1 for work, 1 for home, 1 to be in your backpack), not because they are expensive, but because they just dont sell them in Russia ( the phone is legitimately sold here though). So there should be some other way for the phone to charge rapidly.

So I started experimenting, I thought, that the biggest problem is not the missing IC and negotiation data on USBA-USBTypeC, but the low quality of the cable itself, in other words, its resistanse measured by Ohms is too high. There is one way to compensate the voltage drop on the cable - make the charger voltage cover it, make the charger voltage higher. I took an oscilloscope, a multimeter and a alternate current transformator to measure sudden current drops and spikes.

Experiment

At first I tried 5,2V. Did not help

Then I tried 5,4V. Wow, here it comes better, already charging @ 1,2A ( it was like 400 mA before)

Then I tried 5,6V. The current stayed about 1,2-1,4A ( measured by Ampere App and a physical real current meter)

In all of the experiments I left the DATA pins soldered together - a standart simple way for most phones to think they are connected to a charger.

Then I remembered, that some phones by Sony, some by Nokia and other brands sometimes had a resistor between the DATA pins in the charger, so that, for example you could fast charge a sony from a sony charger, but not from a nokia's one, because sony's had 56kOhm resistor, and nokia had 5kOhm ( values are for example, I dont really remember how it was back then).

So I took the first resistor I found in the box, turned to be 3,2kOhm and soldered it between DATA pins.

And it worked!

At first I saw a fast current spike on the oscilloscope ( could not take a picture, but it was for about 0,3 seconds ), I think the phone was checking capabilities of the charger by giving a load and watching if the voltage drops. The voltage did not drop below normal value ( 5V ). Output voltage of my charger is stabilised and not depending on the load given, so the phone figured that it fits for fast charging, as the voltage did not drop below 5V ( 5,6V on the charger minus about 0,5V at 2A on the cable leaves 5-5,1V at the phone)

Proof:

Charging current as reported by Ampere app ( real current meter said 1,8A, but it is not a precise one )

What you need to do this:

1) A multimeter ( a good one )

2) An output with voltage above 5,5V but below 5,7V. to compensate voltage drop on a cable ( depends on the cable, measure your cable's resistanse, then you can count voltage drop using Ohm's law)

I got mine first on a laboratory power supply, later on a LM2596 board, ( you can buy it here . You just have to adjust the output voltage to 5,6V. Be careful, you must know what you are doing, for this IC to work, input voltage has to be higher than output voltage for like if you need an output of 5,6V, you need about 7V input ( for better effecancy you need about 12V input )

2) A resistor about 3kOhm between DATA pins of the USB cable on the side of the charger

Conclusion

So by these simple manipulations you can charge a N5X ( and possibly N6P) rapidly with a cheap DIY powerbank/charger.

In a few days I will try to reach 3A charging current cap, I will post results

I would be glad to answer your questions and post the detailed schematics if nesessary.

Cheers!