Secret of Fast Charging: How to activate fast charging of my phone?

Nowadays, more and more smartphone brands, like Apple and Samsung, launch new phones without chargers for sustainability reasons and charging technology improvement. Have your friends around you started using “fast chargers”? And have you put effort into choosing a proper charger?


Before the iPhone 15 launch, let’s see how to ensure you enjoy the phone’s fast charging function to the fullest.


You might wonder, how a smartphone can develop from slow-charge to fast-charge. Is it going to damage my phone battery? In short conclusion, phone batteries nowadays are designed to withstand higher wattage power inputs than before, and smartphones can identify according to condition and command the output of a charger, thanks to PD protocol, which brings us to a whole new era of charging speeds.


The charging power (wattage) of a smartphone, refers to the proclaimed maximum charging wattage that the phone can withstand and request from a charger. For instance, iPhone 14 Pro Max can go up to 27 watts, iPhone 15 Pro Max up to 30W, and Samsung Galaxy S23 Ultra up to 45W. However, in practice, charging speeds are affected by numerous factors, and if you’re not careful, you may be unable to fast-charge your phone.


Before we get into the details, let’s review how to calculate the wattage. Here is the simple formula:


Wattage (W) = Output Voltage (V) X Output Current (A)


Here are the four main factors that affect charging speed:


  1.       Power (wattage) of Charger: When the phone supports fast charging, BUT the power (wattage) of the charger is not enough, the charging speed will be affected. For example, if your phone supports 27 watts, but you use a 20-watt charger, the maximum output of the charger will not be able to match the peak demand of your phone, and the effect of fast charging will be reduced. (Learn more – how to choose the best charger)


  1.       Quality of the charging cable: The quality of the charging cable also affects the charging speed. When the charging cable is poorly made, resulting in poor contact, or, too small a diameter to allow enough current (A) to pass through. In addition, when the purity of copper wire used in the charging cable is low, it will cause a voltage (V) reduction while power passes through the charging cable. (Learn more –  the secrets of the fast charging cable)


  1.       Charging circuit of the cell phone: The quality of the charging circuit of the cell phone also affects the charging speed. Poor maintenance or aging of the charging circuit, such as a buildup of lint or rust development in the charging holes or connectors, also affects the charging performance.


  1.       Phone usage: When the smartphone processes many applications, it will consume the power of the smartphone quickly, which affects the charging speed – simple math. In addition, the battery is in very active mode while the phone operates heavily. Charging at the same time results in more burden to the battery. To sustain the battery’s lifespan, Innergie also recommends avoiding using your phone while it’s charging, if possible. 

To summarize, in addition to regular phone cleaning and usage habits, choosing a wattage-sufficient charger and quality-assured charging cable from the manufacturer according to your device is the key to ensuring fast charging.


According to a news leak, the iPhone 15 replaced Lightning with a USB-C charging connector, and the Pro Max version has a charging wattage of up to 30 watts. Make sure you’re not using an under-wattage charger or an unknown-quality charging cable so that when you take your new phone home and charge it, it still charges at a snail’s pace.


We are Innergie, a brand of Delta Electronics, produced on Delta’s production line and sourced from Delta’s components manufacturers. We verify and inspect our product quality with the same standards as international laptop and smartphone brands. A 3-year product warranty is our confidence in quality.


Find the best charger for your digital lifestyle, One For All Charger starting from 30W:  

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