Understanding Fast Charging Standards: Why a 20 Percent Per Hour Charger is Considered Slow

When you pick a charger at your local store, terms like 'fast charger' can often seem misleading. Understanding what constitutes a fast charger and what doesn't is crucial, especially when trying to manage your device's battery efficiently.

What is Considered Fast Charging?

In today's technological landscape, fast charging is more about the rate at which a device can charge, rather than just the label on the charger. A standard charger typically provides around 5 watts of power, aiming to charge a phone from 0 to 100 percent over several hours. However, a fast charger operates at much higher wattage, commonly 18W, 30W, or even higher, enabling much more efficient charging.

The Variables Affecting Charging Rates

The speed of charging can be influenced by several factors:

Amp capacity of the charger: A higher amp capacity allows for faster charging. Length and quality of the USB cable: Longer or lower-quality cables can slow down charging times. Technology capability of the phone and charger: Differences in charging technology, such as Quick Charge, USB-C Power Delivery, and proprietary systems, can significantly affect charging rates.

Marketing labels like 'fast charger' can be somewhat generic. In practice, any charger capable of delivering over 0.5 amps can technically be considered a fast charger, although this still varies widely depending on individual device and charger specifications.

Why a 20 Percent Per Hour Charger is Slow

The charger you found in Walmart that claims to be a 'fast charger' and charges 20 percent per hour is not fast by contemporary standards. A true fast charger typically enables you to charge a device to 80 percent or more in under two hours. For context, a fast charger usually provides 18W or more, allowing for significantly quicker charging.

More specifically, if your phone charger could charge 100 percent of your battery in 2 to 3 hours, it is indeed a standard charger. Fast charging is most efficient when it can bring the battery from 10 to 100 percent in 90 minutes or less. Even less, ideally, fast charging is considered when the battery gets charged from 10 to 20 percent to 100 percent in 90 minutes.

The Two Phases of Fast Charging: CC and CV

Fast charging modes typically operate in two phases:

CC - Constant Current (CC) Stage: This stage occurs from 10% to 80-90% of the battery charge. Here, a constant current is applied to charge the battery as quickly as possible. CV - Constant Voltage (CV) Stage: This stage is used for the final 10-20% of the charge. Here, the voltage is kept constant while the current decreases, ensuring that the battery doesn’t overheat or overcharge.

Even if a charger operates in CC mode, a rate of 20 percent per hour would still be considered slow. Both in the CC and CV phases, a slow rate of charging is inefficient and defeats the purpose of fast charging.

Differences in Charging Standards

Not all 'fast chargers' are created equal. There are different types and standards, such as:

Adaptive Charging: Adapts the charging speed based on the device's needs. Quick Charge 3.0 (QC 3.0): Developed by Qualcomm, this standard supports higher charging rates. USB-C Power Delivery: Used by Apple, this standard is flexible and supports high power delivery. Proprietary Standards: For example, Huawei has its own fast charging standard that may not be compatible with other manufacturers.

Chargers like the Anker PowerPort III Mini are compatible with both QC 3.0 and USB-C Power Delivery, showcasing the variety of options available. In terms of charging speed, a charger that can fully charge a phone from 0 to 100 percent in a couple of hours would be considered fast. A rate of 20 percent per hour, or even 5 percent per hour, would be considered extremely slow.