How much an output amperage should be to achieve a fast charging?   - Page 1
Forum section: electronics / beginners

author: zillah
author_rank: Contributor
timestamp: July 26, 2021, 05:04:03 pm
content: Dear folkTo my understanding, (please correct my confusion)Output voltage most of the time is 5 DCVTo achieve fast charging fast charging amperage should be bigger or equal to 2 DCAI 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 2AAs per the attached snapshots output current was less than 1 ?? Means not fast charging ?https://imgur.com/a/kisBgoWThx

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2021, 05:15:04 pm
content: iPhone fast charging requires USB-C:https://support.apple.com/en-us/HT208137Note 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.

author: zillah
author_rank: Contributor
timestamp: July 26, 2021, 05:23:39 pm
content: Thx tookiQuoteThe 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 Ahttps://tomtom.factoryoutletstore.com/details/47894/high-speed-multi-charger-for-tomtom-.html?category_id=30519&catalogitemid=46382I would assume that can be the case on wall adapter ?QuoteThe cable that I have used it is genuineQuoteBut would that consider as a fast charging ? If not how can we achieve fast charging ?

author: tooki
author_rank: Super Contributor
timestamp: July 26, 2021, 05:47:17 pm
content: Quote from: zillah on July 26, 2021, 05:23:39 pmOK, 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.

author: zillah
author_rank: Contributor
timestamp: July 26, 2021, 10:17:27 pm
content: NotedThx for your help

author: tooki
author_rank: Super Contributor
timestamp: July 27, 2021, 02:27:04 pm
content: Quote from: zillah on July 26, 2021, 10:17:27 pmSure thing!

author: perieanuo
author_rank: Frequent Contributor
timestamp: July 28, 2021, 06:58:27 am
content: the 'battery' decides the fast charging voltage/currentso 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 onesthis is a short and simple "resumé":https://www.pcmag.com/how-to/what-is-fast-charging