I have succumbed to the iPad phenomenon and purchased a new iPad 2. While I am very pleased with the device I have found that it will not charge when plugged into a USB on my desktop PC (quite a new computer running Windows 7). One person said that it should charge and another said that the USB port was the problem. However, looking on the internet seems to indicate that many other iPad users around the world have experienced the same problem. It is being suggested that the power output from a USB port is insufficient to charge the iPad, although some have suggested that there are some models of Apple computers that will charge an iPad. Is this an issue you have come across and is there a solution?

Well firstly, congratulations on your purchase! This is a very good question, and something which I have also encountered previously. The short answer is that the USB port on your computer is not providing enough current for the iPad to charge. A standard USB port provides around 500 mA at 5 volts for connected devices, but this is not enough to charge an iPad (among other Apple devices) so you will probably instead notice that the iPad says “Not Charging” next to the battery indicator. If you switch off the display the iPad may charge, given the reduced power needs due to the screen being switched-off, but even if it does it will be a very (very) slow charge. The recommended way to charge an iPad is to use the provided power adapter which provides significantly more current and will also charge the iPad much quicker. The recommendations for charging an iPad are available on the Apple Knowledge Base at support.apple.com/kb/HT4060 .

You are correct that some Apple computers are able to charge these devices, because they are equipped with high-powered USB ports. You can find an explanation of the workings of these high-powered ports at support.apple.com/kb/HT4049 . Even this article recommends using the power adapter to charge the iPad as it will still be quicker than charging using a high-powered USB port. Some PCs may also have higher-powered ports, but this all depends on the make and model of the computer. Presumably the reason that Apple computers have these ports is because Apple has designed them into the computer due to the increased power needs of their devices.

For the sake of completeness, ASUS have released a utility which apparently can make charging iPods, iPhones and iPads quicker on all PCs. This is available at event.asus.com/mb/2010/ai_charger . I have never used this utility and while some users report success, I advise extreme caution as other users have reported system instability (particularly iTunes hanging) when this utility has been installed. I have included mention of this utility here purely so I could include this warning, so only use this at your own risk. If you do decide to install the utility then ensure you create a system restore point and have a backup of your data, as some users have reported that when they attempt to uninstall the utility it causes problems with the USB and other drivers on the computer requiring rolling back to a restore point (and in some extreme cases have required a reinstallation of Windows). I would recommend against using this utility and instead just use the wall charger which is the recommended method for charging the iPad.