Charging an iPhone With a Computer Vs. a Wall Outletby Tyson Cliffton
Heavy use of your iPhone can drain your iPhone after just a few hours or less. Understanding the differences between a wall outlet to charge your iPhone versus your computer will help you select the charging method that works best for your current situation. Other factors such as the type of USB port you're using on your computer and whether you're using your phone while charging it can also play a role.
The biggest difference between charging your iPhone through a wall outlet using the AC adapter versus charging your device through a USB port on your computer is that the charging time using a wall outlet is faster. This is because your computer has to distribute available power across an array of internal components and can't dedicate all of its power to charging your iPhone. AC power offers a larger power source that results in the faster charge time.
USB Port Speed
There are two types of USB ports on computers: high speed and low speed. High speed USB ports are typically found on either your computer tower or on your laptop. Alternatively, low power USB ports are often the ports found on your keyboard or monitor. High speed USB ports will charge your iPhone, while low power USB ports either won't charge your device, or will charge it very slowly.
USB Port Settings
Even if you are connected to what should be a high power USB port, the settings for that port may have been changed so that port operates as though it's a low power USB port. Alternatively, if you notice your iPhone isn't charging while your computer is asleep or hibernating, check the settings for that USB port and make sure it's set up to operate while the computer is in different modes.
Using iPhone While Charging
If you notice that your iPhone isn't charging as fast it usually does when connected to either a wall outlet or your computer, it may be because you're using the device. For example, you may be browsing the Internet through Safari while connected to a wall outlet or syncing with iTunes while the device is connected to your computer. Your iPhone will charge the fastest if you don't use it while it's charging.