Apple ships the iPad with a 10-watt adapter that provides 2 amps of power at 5 volts. This adapter is more than powerful enough to run and charge the iPad at the same time. It also comes with a detachable cable that you can use to sync the iPad or to charge it with other devices.
The iPad Challenge
Charging an iPad with a 5-volt source, which is the power that a USB port generates, is challenging because it has a large battery that needs a considerable amount of power to charge. The first two generations of iPads have 25 watt-hour batteries and the third and fourth generation iPads need almost twice as much power to charge their 42.5 watt-hour batteries. For this reason, Apple supplies a 10-watt power supply.
Your iPad can charge from a USB port. A traditional USB port provides 500 mA of current, which is 25 percent of what the Apple charger delivers. Some computers have high-power USB ports, though. A high-power USB port can deliver around 1200 mA of power. Either port actually has enough power to charge an iPad. The challenge is charging it while it's in use. A 500 mA port may not be able to keep up, although it can trickle-charge an iPad that isn't in use. A 1200 mA high power port should work. In either case, your iPad may display a message that says it is "Not Charging." The real test is to leave your iPad plugged in for a while and see if its battery level goes up.
Wall and Car Chargers
Given that the iPad can charge from a computer USB port, it follows that the iPad can also charge from external USB chargers other than the one that it comes with. Some manufacturers make special high-power chargers that deliver the same 10 watts as the charger that Apple includes with the iPad to accommodate its current requirements. To this end, any USB-equipped car charger can also work. You could even use a solar charger or a crank charger, provided it has sufficient power output.
If you need to charge your iPad where you don't have access to a car battery or a wall outlet and don't want to use a solar or crank charger, you have another option. You can bring along an extra battery that is already charged. Portable power packs hold high-capacity rechargeable batteries and can be plugged into the iPad to power it or to recharge its battery.
Information in this article applies to iPads released through April of 2013. It may vary slightly or significantly with other versions or products.
- Photo Credit Jupiterimages/Photos.com/Getty Images