Have your tried to charge an iPad by connecting the charging cable from your computer to the iPad and noticed something strange? If you look closely at the iPad while it is plugged in you may see "Not Charging" in the upper right hand corner of the tablet. Don't worry the iPad is probably not broken, more likely the computer USB port does not have the required juice to charge the iPad. That is because the Apple iPad has higher charging requirements than other USB devices. Specifically the iPad expects 10w of power to optimally charge the device. To compare, a normal USB port produces only 2.5W of power. If you try to plug the iPad charging cable into a standard USB port, you may not be able to adequately charge the device. This is especially true for older computers and USB hubs. It turns out newer computers, such as new Macs, with special USB ports can do a little better job. So what is the best way to charge an iPad?

  • Whenever possible, use the included power brick that comes with the iPad to charge the device. It produces 10W of power, which is 20 times the standard USB wattage. This is supposed to fully charge an iPad in a few hours no matter what you are doing with it. Many third party manufacturers have started to sell charging bricks for the iPad if you need a spare.
  • If you do not have the power brick available, look for a high-power USB port. These high-powered USB ports are rated to deliver slightly over 5 Watt of power. This is double the standard USB port but way lower than the optimal 10W that the iPad needs. This means that the iPad will charge much slower using a computer than with the iPad brick. In addition, the peak power consumption of an iPad is estimated to be just above 5W so you can still fail to adequately charge the iPad if it is doing a lot of work. High-powered USB ports can be found on the newer Macs or on some USB hubs. Fortunately, the iPhone charging brick or other especially built iPhone chargers are also high-powered USB ports. So you may want to carry the more svelte iPhone brick around as a back up charger.
  • If neither of the above options are available, plug the iPad into a standard USB port. You will still see the "Not Charging" message because the iPad is using more power than the standard USB port can provide. However if you put the iPad into sleep mode, the iPad will now receive less power than it uses. You will have to keep the iPad in sleep mode continue to charge it. However, this may take a very long time to charge the iPad.

Apple has posted tech support posting to help iPad owners.