IPhone – Apple iPhone 5 doesn’t charge attached to a laptop

The iPad uses a 10W charger. The iPhone has a 5W charger. Most older computers only support the original USB spec of 2.5W USB port power support. Your iPad, when on, uses more than 2.5W, so it will not charge unless it's turned off, and when off it will charge at less than 1/4 the speed of the normal iPad charger. That can be up to 16 hours for a fully depleted iPad.

Newer Apple computers, and computers that support USB3.0, support higher USB power standards, but if your computer doesn't then you'll need to invest in a new charger for your iPad.

Note that the iPad will generally charge off other USB chargers from other manufacturers, but only at a slower rate than the original iPad charger, unless the charger you use is specified to charge the iPad. When the original iPad came out 10W USB chargers were not common.

I know, in most cases, this problem to be the usb port on the iphone. Unfortunately this part seems to be a part which only one in five of these parts to be good from experience. Either the mic or data port are defective which makes a diy repair frustrating. Most people will change it once they hit a defect part and give up. Don't give up. Trying to help people who are frustrated as I was. Usually occurs when you update with a port having bad contacts and ends up with a no sync or no voice on phone mic. May not be what you want to hear.