Phones and tablets have become essential for many aspects of modern life. This is why the value of long, uninterrupted battery life has risen as well. But even with continued advances in sleeker and more robust power storage, all mobile devices will need to be charged at some point.


The sooner a user can take their device off a charger will full power, the better. This need has led to a rise in fast-charging solutions. Faster charging is a benefit that’s touted by phone manufacturers, developers of fast charging apps, and makers of plug-in chargers and cables.

Claims of 80 percent charging in under 30 minutes or zero-to-complete battery charging in just one hour are now common in all types of tech products. Skeptical consumers may wonder just how fast charging works and whether a super-fast charger, cable, or app will live up to its promises.

While rapid charge capabilities and devices come in many shapes and forms, most fast charging is accomplished by boosting the amount of power, or watts (W), that can reach a battery in a given time.

Fast chargers and charging capabilities increase the 2.5W to 15W charging standards to levels as high as 100W. While this sounds fairly straightforward and can be an attractive prospect for anyone charging their phone multiple times a day, there are a few factors to consider.

Fast Charging And Adaptive Charging

It’s easy to think that plugging in a phone amounts to a uniform charging process, but in reality, lithium-ion batteries charge in different phases, and each phase has a different speed—some of which can be sped up easier than others. In the first state, also known as the constant current phase, voltage rises at a high level and power is fed to the battery.

The second charging state is the saturation phase. At this phase, the voltage reaches its peak and the current decreases, which means the charging process will slow as the battery nears a full charge. Stage three is the tickle/topping phase. At this point, the battery has reached a full charge and the current drop stops at a set level.

The device then cycles through short increases in voltage while the device is in standby mode to “trickle” or “top off” power. Different charger types may modify different charging phases to make the overall process more efficient, but most rapid charge processes accelerate the first phase. This means that a fast charger can quickly boost a device’s battery to 75-80 percent, but getting to the full charge will not occur at the same rate.

A process known as adaptive charging utilizes this cycle in a similar manner. Users can elect to link their phone’s sleep and alarm settings with a slow-and-steady overnight charging process. Adaptive charging ensures the battery reaches 100 percent before the user’s usual waking time. Adaptive charging is also designed to ensure optimal phone usability while the longevity battery is preserved.

Many fast charging apps operate on a similar phase principle. These digital tools modify device settings to optimize the charging process regardless of the charging hardware. They are typically activated when the device is plugged into a charger but they may also extend battery life by modifying the performance of background activity to prevent non-essential battery use.

Can Fast Charging Damage A Battery?

Obtaining the fastest phone charger may seem like a great idea for anyone who’s frequently using and charging their mobile device. But with the convenience of the fast charger, there are some potential drawbacks. Increasing charing rates by increasing current and voltage also means generating a lot more heat in a device’s battery.

Credit: Malcolm Koo

An occasional rapid charge may not have a notable negative impact, but regularly fast-charging phones and tablets with lithium-ion batteries will degrade them over time. This can be exasperated if a device is fast charged and heavily used on a continuous cycle that limits cool-down times.

For this reason, fast chargers are not always recommended as a primary charging option but only when a quick charge is absolutely necessary.

It’s also important to keep in mind that fast chargers do need to be compatible with a device to deliver notable results. Charging speed capacities are ultimately limited to the design and condition of the device’s charging circuit, as well as other hardware like cables.

The fastest charger on the market may not have much of an impact on a phone or tablet that has a limited capacity charging circuit or when paired with a standard cable.

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