How Fast Charging Works
Amperage x Voltage = Watts
The basic components of charging are amperage, voltage, and watts. Amperage (or current) is the amount of electricity flowing from the battery to your phone or other connected device. Voltage is the speed or strength of the current. Watts are amperage multiplied by voltage. A common comparison used is a watering hose. Amperage (or current) is the hose width, voltage is the water pressure, and watts is how much water is coming from the hose.
So, how does Fast
Charging happens in two phases. In the first phase, a higher voltage increases the charging rate. Fast charging chargers leverage this phase to increase power flow. Once the battery has received most of its charge, the charger will decrease voltage to preventing overheating or overcharging, ensuring your smartphone and charger are both safe.
Exact speeds vary by device safety requirements.
How do you charge faster?
Before you embark on a high-speed charging journey, you’ll need the right equipment. Your smartphone, tablet, laptop, or other device will all need to use the same fast charging standard. In some cases, even your cable will need to be compatible with the fast charging standard used in your device and charger.
Once you have a charger and cable with the fast charging standard compatible with your phone, laptop, or other device, take note of the maximum charging speed for both. For example, if you are using a 27W charger with a smartphone that has a maximum charging speed of 18W, the phone will charge at 18W.
Types of Fast Charging Standards
The original and most popular types of fast charging standards are USB Power Delivery (or USB-PD) and Qualcomm Quick Charge. In addition to these, you may be familiar with TurboPower, Adaptive Fast Charging, or SuperCharge. Many of these are based on Qualcomm Quick Charge and have been rebranded for marketing purposes. Similarly, Apple uses USB-PD standard in their devices, so your iPhone will be compatible with all USB Power Delivery chargers and cables.
|Fast Charging Standards|
|Standard||Quick Charge||USB Power Delivery|
|Charge Up To||27 watts||100 watts|
|Developed By||Qualcomm||USB Implementers Forum|
|Connector Types||USB-A, Micro USB and USB-C||USB-C|
|Supported By||Older Samsung, LG, and other smartphones and tablets||iPhone 8 and later, Google Pixel, iPad Pro 10.5” and later, Samsung S10 5G, Samsung Note 10+, Samsung Note 20 devices and later, Samsung S20 devices and later, and other smartphones and tablets|
Is fast charging safe?
Because these technologies allow your smartphone to charge faster than standard charging speeds, your phone and charger may become warm while charging. To ensure you’re always charging safely, use high quality chargers and cables that have all relevant certifications. When using fully certified accessories, a fast charge is as safe as standard charging.
closeIs fast charging bad, or does it damage batteries?
To ensure safety and optimal speeds, always check that your fast charging accessories are certified to be compatible with your smartphone. This is most likely going to be Quick Charge or USB Power Delivery. Certified accessories ensure the charger or cable meets performance and safety standards. With a charger or cable that’s not certified, there’s an increased risk of shorting or overheating, which can damage both your device and charger.
Your charger may get warm while powering devices, but if it’s produced by a reputable manufacturer and certified compatible, there’s nothing to worry about. These certifications mean a series of safety measures have been taken. A controller chip regulates the flow of electricity to your battery, ensuring there aren’t any dangerous spikes in the current while temperature and voltage controls keep your charger running within safe parameters.
Before purchasing or using a fast charging accessory with your device, you should first verify that the product you are using is:
- Manufactured by a trusted brand
- Qualcomm Quick Charge or USB Power Delivery certified
- Includes technical specifications and warranty details that protect your device from damage caused by the accessory
closeWhy is fast charging not working?
There are a few reasons why fast charging may not be working on your device. Below are a list of common causes and suggested trouble shooting:
- Your device might not support fast charging.
View our list of devices that support fast charging below to check.
- Your phone may not recognize the accessory is connected.
Try unplugging and re-plugging in the fast charger from the outlet and device.
- Your circuit breaker may have been tripped and is not working.
Try plugging something else into the outlet or plugging your fast charger and device into another outlet. If nothing is working in the outlet, try resetting its circuit breaker.
- For Samsung devices: you may need to enable fast charging and or turn off your screen.
See our FAQ on how to enable fast charging on Samsung phones for more details.
- Your device is having a software issue.
First, make sure your software is up-to-date. If your software is up-to-date, try restarting your device. As a last resort, you can also choose to factory reset your device.
- Your device is having a hardware or battery malfunction.
If it is an older device, this might be the case. Try using the fast charger on a different device. If your fast charger works, the problem is with the first device.
- Your fast charger could be faulty or broken.
Try using the fast charging accessory on a different device. If it still does not work, the problem is likely with the fast charger.
If following steps 1 – 7 does not solve the issue, contact the fast charger accessory manufacturer for additional assistance.
closeWhich iPhone and Android devices support fast charging?
Fast charging is available on:
- iPhone 8 and later
- Samsung Galaxy S6 and later
- Pixel 2 and later
- iPad Pro (1st Generation) 12.9inch and later
The number of devices enabled with fast charging technology is growing every day, check your device’s manufacturer for the most up-to-date information.
closeHow do I turn on fast charging?
Some devices need to have fast charging enabled to work. If fast charging needs to be enabled on your device, you can refer to device manufacturer. For Samsung devices, follow the steps below.
Go to Settings > Device > Maintenance > Battery > Advanced Settings and toggle on fast cable charging.
Note: your screen must be turned off for fast charging to begin once enabled on your phone.
closeWhat is adaptive fast charging?
The original and most popular types of fast charging standards are USB Power Delivery and Qualcomm Quick Charge, but you may have heard about Adaptive Fast Charging, TurboPower, and SuperCharge. Most of these are based on Quick Charge or USB Power Delivery and have been rebranded for marketing purposes.
closeHow do I identify a fast charger?
To ensure a charger will fast charge your device, you can check with the manufacturer for compatibility. As a general rule, a charger needs to be at least 18W from a single port to deliver fast charging. You can also check for the USB Power Delivery and Quick Charge logos on packaging.
closeHow fast do phones charge with fast charging?
USB Power Delivery (iOS/iPhone and Android/Google Devices):
- iPhone 8 or later will charge from zero to 50% in 30 minutes*
- iPad Pro recharges from zero to 50% in 60 minutes*
- Pixel 2, 2 XL, 3, and 3XL recharge from zero to 50% in 37 minutes*
Listed USB-PD devices and speeds reflect capabilities as of July 2019.
Qualcomm Quick Charge (Samsung, LG and other smartphone and tablet devices):
- Quick Charge 3.0-compatible devices charge from zero to 80% in 35 minutes*
- Quick Charge 4.0-compatible devices charge from zero to 50% in 15 minutes*
Listed Quick Charge devices and speeds reflect capabilities as of July 2019.
*Charge time varies with environmental factors; actual results will vary.
closeHow can I tell if my phone is fast charging?
When your phone is fast charging, a small lightning symbol will appear on your phone.
Fast charging is automatic when available and does not deliver a confirmation of charging speed.
For Pixel, LG, and other smartphone devices:
Many devices display ‘Charging rapidly’ or ‘Fast charging’ instead of simply ‘charging’ on the lock screen.
For other devices, please contact your manufacturer.