Author Topic: How much an output amperage should be to achieve a fast charging?  (Read 856 times)

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Offline zillahTopic starter

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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 ?

https://imgur.com/a/kisBgoW

Thx
 

Offline tooki

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Re: How much an output amperage should be to achieve a fast charging?
« Reply #1 on: July 26, 2021, 05:15:04 pm »
iPhone fast charging requires USB-C: https://support.apple.com/en-us/HT208137

Note that the quality of the USB cable makes a massive difference in charging speed, as an iPhone (or iPad) will detect excessive voltage drop (due to resistance in a bad cable, or a charger that can't keep the voltage up) and limit its current draw. In some of my tests (a while ago, so I don't remember the precise values), a cheap cable limited my iPad's charging to around 700mA while on a good cable it drew 1.1A. But the 750mA for your iPhone on a 5V charger sounds about right to me, I don't think I've ever seen more than that for an iPhone on 5V.
 

Offline zillahTopic starter

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Re: How much an output amperage should be to achieve a fast charging?
« Reply #2 on: July 26, 2021, 05:23:39 pm »
Thx tooki

Quote
iPhone fast charging requires USB-C

The article was published 2020,,,,I guess before type C,,,,, USB type A was doing a fast charging as well ,,,,please see the link below for car charger by TomTom it says Fast Charging and it is using USB A

https://tomtom.factoryoutletstore.com/details/47894/high-speed-multi-charger-for-tomtom-.html?category_id=30519&catalogitemid=46382

I would assume that can be the case on wall adapter ?

Quote
a cheap cable limited my iPad's charging to around 700mA
The cable that I have used it is genuine

Quote
But the 750mA for your iPhone on a 5V charger sounds about right to me

But would that consider as a fast charging ? If not how can we achieve fast charging ?

 

Offline tooki

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Re: How much an output amperage should be to achieve a fast charging?
« Reply #3 on: July 26, 2021, 05:47:17 pm »
Thx tooki

Quote
iPhone fast charging requires USB-C

The article was published 2020,,,,I guess before type C,,,,, USB type A was doing a fast charging as well ,,,,please see the link below for car charger by TomTom it says Fast Charging and it is using USB A

https://tomtom.factoryoutletstore.com/details/47894/high-speed-multi-charger-for-tomtom-.html?category_id=30519&catalogitemid=46382

I would assume that can be the case on wall adapter ?

Quote
a cheap cable limited my iPad's charging to around 700mA
The cable that I have used it is genuine

Quote
But the 750mA for your iPhone on a 5V charger sounds about right to me

But would that consider as a fast charging ? If not how can we achieve fast charging ?
OK, we need to establish some basics here!

1. "Fast charging" does not have a fixed, industry-standard meaning. That's why I said specifically "iPhone fast charging", since the only device you mentioned was an iPhone X. Every product can have its own meaning of "fast" charging, with its own implementation and/or requirements.

2. USB-C has been around since 2014.

Thus:
In Apple's iPhone charging definition, 5V/750mA charging is not considered "fast charging", it's just the maximum of normal speed charging. (Yes, this does indeed mean that the 5V/500mA chargers supplied with most iPhones charge them slower than they're capable of, presumably to be gentler on the batteries and allow for the cheaper, more compact charger size.) The charging current you're seeing is correct for the charger type being used.

TomTom's charging speed definitions are irrelevant to Apple devices and vice versa. iPhone "fast charging" requires USB-C; other devices can require whatever they want. Various fast charging systems have existed for a while, like Qualcomm QuickCharge.
 

Offline zillahTopic starter

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Re: How much an output amperage should be to achieve a fast charging?
« Reply #4 on: July 26, 2021, 10:17:27 pm »
Noted
Thx for your help
 

Offline tooki

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Re: How much an output amperage should be to achieve a fast charging?
« Reply #5 on: July 27, 2021, 02:27:04 pm »
Noted
Thx for your help
Sure thing!
 

Offline perieanuo

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Re: How much an output amperage should be to achieve a fast charging?
« Reply #6 on: July 28, 2021, 06:58:27 am »
the 'battery' decides the fast charging voltage/current
so you took battery specs, the maker tells you accepted current and voltage, then you implement the charger with margin for voltage (charge's Vcc should be bigger than battery package with the margin final transistor permits+ some reserve) and you convince the charging circuit to adapt the voltage and current according to specs.
 3.7v acc needs some voltage/current capacity depending of his current capabilities, if tomorrow motorola decide to put 10000 mAh battery on one phone, the charging current will meet the new specs and the oltage will increase at minimum 10V.
as far as i know, nowadays 5V for older fast chargers with at least 2.1A and 12V and more for newer ones
this is a short and simple "resumé": https://www.pcmag.com/how-to/what-is-fast-charging
 


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