The best and most efficient way to charge your iPad is to use the charger that came with it and plug that into a good wall outlet.
Consider the Asus ai Charger. It's a driver that will allow a Windows Computer's USB ports to charge an iPad. I make no guarantees. I can only say that I've loaded it on a Dell laptop and a Dell desktop and it works with no problems. If you search this forum for Asus ai charger, you will find that others have reported that it has worked on other brands of computers as well. If you decide to try this I suggest you create a restore point before installing. Again, I make no guarantees.