Hello, I really curios about fast charging and how its relation with volts and ampere, like for example my chargers output specification are 5V

2.5A / 9V

2A / 12V

1.5A so which one of the output does my chargers provide and when because there's 3 outputs, and what would be the specification of my cable has, it's type c of course , and the type c cable has so many specs like 1.8A, 2.1A, 2.4A, even 3A and what would be the best specification option for my charger to use , like when I used the 3 amps one will it still deliver max 2.5 amps or what ever my chargers supplied (I still don't know which one because there are 3 outputs) and when I used 1.8A cables will it bottleneck my chargers output if it provides 2A/2.5A (still don't know which one would be and when). and lastly the relations between voltage and ampere is V=I.R right? so why does the volts are increasing but the ampere are decreasing.

Here is my chargers specs

 

PS : I'm asking when because I assumed the outputs are time variant, because my phone help support says my fast charging is only up to 50% only but in my case even after 50% of charging the "charging rapidly" notifications is still there. And recently they says my phone requires the 9V

2A outputs, so the outputs is totally dependant to the device?, and my chargers is like 'universal' to the device that requires one of the three output? and from their explanations of my fast charging capabilities just up to 50% of charge ( even though I'm still not sure because even when it's over 50% the "charging rapidly" notifications is still there ) so after 50% the output is decreased? if it's decreased then which one of the two options is the outputs going to be if it isn't 9V

2A. And which of the 3 outputs is the fastest?

 

why does the volts are increasing but the ampere are decreasing.

That's because the power output (V x I) from the charge is fairly constant thus
5V x 2.5A = 12.5W
9V x 2A = 18W
12V x 1.5A = 18W
(The 5V output lower power may be due to the supply being less efficient at a low voltage.)

The output you use is the one with the correct voltage.
The current will take care of itself as the phone takes whatever current it needs.

 

The output you use is the one with the correct voltage.

What do you mean by this? Btw thanks for the explanation

 

What do you mean by this?

I mean, the output voltage you use is what the device being charge requires.
You stated "And recently they says my phone requires the 9V

2A outputs" which, if I understand you correctly, means you should connect the phone to the 9V output of the charger.

 

you should connect the phone to the 9V output of the charger.

So if I want to buy cables I should get cables with 2A or more? anyway the charging ports is just one so the chargers is automatically choosing the correct output?

 

anyway the charging ports is just one so the chargers is automatically choosing the correct output?

If you mean the correct output current, yes.
It just takes the current it needs (as long as it's no more than the supply output rating).