Written by 12:22 PM Tips

What’s the difference between 1A and 2A written on the charger?

・The difference between 1A and 2A is the amount of current that can flow.

The 1A and 2A on AC adapters and mobile batteries are numbers that indicate the difference in the amount of current that can flow through the USB port. The higher the number, the more electricity can flow through it, so 2A can supply more current to a smartphone or tablet than 1A.

More current means a much higher charging speed, and 2A will charge your device faster than 1A.

In fact, using the iPhone as an example, comparing the charging speed of a 1A charger and a 2A charger, the time it takes to go from 0% to 100% using a 1A charger is about 2 hours and 20 minutes, while a 2A charger takes about 1 hour and 55 minutes. If you look at the total charging time, it’s only about 25 minutes shorter, but if you compare the percentage of the battery that can be charged after leaving it at 0% for an hour, the 1A charger takes 60% and the 2A charger takes 87%, a difference of 27%. (Both measurements were taken with an iPhone 6s)

The reason for the 25-minute difference in total time is that when the iPhone battery level exceeds 70%, a function that reduces the amount of current flowing forcibly to reduce battery pain operates, slowing down the charging speed.

Some tablets, such as the iPad, require an AC adapter that supports at least 2A output for charging, and in some cases, 1A output is fundamentally insufficient for charging.

・V represents the power to push out electricity.

Next, let’s talk about the unit V, which is always written together with A.

V” (volt) is a unit of force that pushes out electricity, like the speed of water flowing in a river.
By the way, “A” (ampere) is a unit that represents the amount of electricity flowing, and if we compare it to a river, it is like the width of the river.

For AC adapters and mobile batteries, the number 5V is most commonly used.
As mentioned earlier, this indicates that “the power to push out electricity is 5 (a river with a water flow of 5).

AC adapters, mobile batteries, and cables that use the USB-A standard are generally not allowed to use any other V than 5V, and rarely use any other V than this. However, Qualcomm Quick Charge provides a voltage of 9V or higher to the USB-A terminal for safe and fast charging, so it cannot be said that products that use voltages other than 5V are dangerous.

If it is 5V, the only factor that affects the charging speed is the number of A’s, so you don’t need to think too much about the number of V’s. However, this is only the case for USB-A.

If it’s 5V, the only factor that affects the charging speed is the number of A’s, so you don’t need to think too much about the number of V’s. However, this is only true for USB-A, and not for USB Power Delivery.

・Can a 1A charger charge a 2A product?

Can a 1A charger charge a 2A product? In other words, can a charger that can only draw a small amount of power charge a device that requires a large amount of power?

This is also a point of concern when choosing a charger.

As it turns out, there are two types of chargers: those that can charge and those that cannot.

For smartphones, 1A can be used to charge devices without any problem, although it will take longer to charge, as was the case with the 1A charger included with the iPhone until recently.

However, for tablets such as the iPad, the battery will not decrease or increase while it is connected to the power supply. The battery will not decrease or increase while connected. A mobile battery, for example, can increase the remaining charge, albeit slowly.

Also, the maximum amount of electricity that can flow from a 1A charger is 1A, so even if you connect a device that requires 2A output to a 1A charger, the charger will not fail or the device to which it is connected will not fail. However, since the amount of heat generated tends to increase, it is important to keep in mind that it may cause low-temperature burns after use and accelerate the deterioration of the charger.

・What about the opposite?

So, what happens when you connect a 2A charger to a device that requires only 1A output, or in other words, when you connect a device that does not require a lot of power to a charger that can draw a lot of power?

As with the previous question, there are very few cases where this will be a major problem, and in most cases it can be used without any problem.

However, it is important to note in both cases that these are the results of using a safe charger, and using an inferior product can lead to damage or even burn out of the device.

・Recent years have seen the emergence of W numbers and numbers exceeding 2A

With recent improvements in charging technology, it has become possible to charge various devices at higher speeds.
As a result, chargers are also changing with the times, such as USB-PD chargers that can handle up to 5A instead of the usual 2.4A.

With the increase in the amount of power that can be handled, “W” (watt), which has not been used extensively in the past for chargers for smartphones and other devices, is increasingly being used to indicate the specifications of chargers.

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