# How much an output amperage should be to achieve a fast charging?

#### zillah

Joined Jul 21, 2015
9
Dear folk

To my understanding, (please correct my confusion)

Output voltage most of the time is 5 DCV

To achieve fast charging fast charging amperage should be bigger or equal to 2 DCA

I did a test using 2 USB power meters and 2 different lightening cables and 2 wall adapters (10W, means 2A as voltage always 5) to test it on iPhoneX which can take up to 2A

As per the attached snapshots output current was less than 1 ?? Means not fast charging ?

Thx

#### Papabravo

Joined Feb 24, 2006
20,600
Just to be clear. You CANNOT force current into a load that will not take it. Just because a power supply or a charger has the ability to deliver large currents does not mean the load has to accept them. The LOAD will take whatever current it needs for whatever state it is in -- no more, and certainly no less.

#### Dodgydave

Joined Jun 22, 2012
11,149
The phone dictates the charge rate not the charger, if the battery is very low say 20%, then the phone might fast charge it upto 60%, then drop the current to normal.

#### zillah

Joined Jul 21, 2015
9
Thx Papabravo
Just to be clear. You CANNOT force current into a load that will not take it. Just because a power supply or a charger has the ability to deliver large currents does not mean the load has to accept them. The LOAD will take whatever current it needs for whatever state it is in
Yes I am aware of that

#### zillah

Joined Jul 21, 2015
9
The phone dictates the charge rate not the charger, if the battery is very low say 20%, then the phone might fast charge it upto 60%, then drop the current to normal.
Noted
Thx

#### Papabravo

Joined Feb 24, 2006
20,600
Thx Papabravo

Yes I am aware of that
Let's just say you have a strange way of demonstrating that.

#### Tonyr1084

Joined Sep 24, 2015
7,549
A charger capable of high amperage will charge the battery as fast as the battery wants to be charged. Both you and Papabravo have discussed that. However, if a battery is capable of accepting 2 amps but the charger itself is only capable of half an amp then the battery will have to live with what's available. But I suspect you already know this as well. Sometimes the obvious needs to be stated because not everyone everywhere is aware of all things. Some things are new to some people. So don't take offense please.

#### zillah

Joined Jul 21, 2015
9
Thanks Tony

Some things are new to some people. So don't take offense please.
Not at all I am here to learn this is why I posted my equation

But I suspect you already know this as well.
This assumption may be not quite right ,,,,,And I tested that by using an old iphone or samsung wall charger their output where 5v and 1A or less than 1 comparing to origin iPhone x wall charger that their output where 5v and 2A,,,,the later is faster because it is capable to supply more current
And tested that in car with default USB port charger rated 1 A comparing to ANKER charger that rated 2.4 A when I charge iPhoneX