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

zillah

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Dec 24, 2005
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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 ?

View: https://imgur.com/a/kisBgoW


Thx
 

Eximo

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There are many factors that pertain to fast charging.

State of the battery charge.
Battery temperature.
Possibly system temperature
Cable capacity, particularly with apple devices.
USB handshaking

Devices have hardware and/or software to negotiate charging rates. (Older standards used resistors for a very simple capability logic, newer types communicate chip to chip before sending significant amounts of power) If any link in that chain (including your current meters) doesn't meet that standard it will assume a lower charging standard. Fast charging likely would not work if the battery is close to capacity either, that is undue stress to the battery and could lead to premature wear.

Not all USB wall worts are built the same either. What they advertise and what is actually inside them is quite different. There are even fake versions of the 'real' thing out there where they replace the guts of an OEM charger with cheaper internals.

That current meter is going to get you the average, an oscilloscope could show you the high ripple or straight DC chopping of AC that some cheap units do.
 
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 ?

View: https://imgur.com/a/kisBgoW


Thx
You’re using a USBA cable. You need a USB C cable for fast charging. Also why are you assuming the Voltage is always 5? My fast charge varies from 5 to 20v
 

Eximo

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You’re using a USBA cable. You need a USB C cable for fast charging. Also why are you assuming the Voltage is always 5? My fast charge varies from 5 to 20v
You are seeing the power supply end, that is typically Type A, the other end can basically be whatever, though typically on late model phones it is Type C.

There are fast charging technologies that use a higher voltage, but that doesn't apply here, pretty sure that is a 5V supply.
 
You are seeing the power supply end, that is typically Type A, the other end can basically be whatever, though typically on late model phones it is Type C.

There are fast charging technologies that use a higher voltage, but that doesn't apply here, pretty sure that is a 5V supply.
Usba is limited in voltage though. Lighting only uses USB 2
 

Eximo

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Usba is limited in voltage though. Lighting only uses USB 2
Not sure what part of there are faster technologies and mentioning that we are limited to 5V here needs re-explanation. Slow charging, or as it was called when it was released, charging, and there is fast charging, when phones and other devices were capable of charging faster than the old standard There are newer standards, yes. Including 20W charging on a USB type A to Type C cable, but here the power supply is limited to 2A, and it isn't even reaching that. Could be any number of the reasons stated in my original post.
 

jay32267

Champion
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 ?

View: https://imgur.com/a/kisBgoW


Thx
The iphone doesn't necessarily have to take 2 amps.

For instance...if the iphone is charged or near full charge it's not going to take 2 amps.
 
Not sure what part of there are faster technologies and mentioning that we are limited to 5V here needs re-explanation. Slow charging, or as it was called when it was released, charging, and there is fast charging, when phones and other devices were capable of charging faster than the old standard There are newer standards, yes. Including 20W charging on a USB type A to Type C cable, but here the power supply is limited to 2A, and it isn't even reaching that. Could be any number of the reasons stated in my original post.
Just saying with iPhones fast charging is only over the USBC to lightning wires
 

hang-the-9

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Usba is limited in voltage though. Lighting only uses USB 2
This is for output through a computer port, not a USB cable connected to a wall plug. It can also be affected by the cable quality. A wall charger, even if it has a USB plug, is not restrained by the USB computer standard for power, only as far as it should not be able to cook the devices it's trying to charge.
 

lvt

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You’re using a USBA cable. You need a USB C cable for fast charging. Also why are you assuming the Voltage is always 5? My fast charge varies from 5 to 20v
It depends on the technology used (using voltage or current, or both), for example my HTC phone uses 9V for fast charge but my other Oppo phone uses 5V for fast charge.
 
This is for output through a computer port, not a USB cable connected to a wall plug. It can also be affected by the cable quality. A wall charger, even if it has a USB plug, is not restrained by the USB computer standard for power, only as far as it should not be able to cook the devices it's trying to charge.
Depends iPhones can detect cables and refuse to work with none certified ones and ultimately the power draw is decided by the phone
 
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