This is my second unit; I returned the first one because of a charging issue. As a few other purchasers have written, the Power Covers sometimes have an initial problem that appears to be due to their age (i.e., these covers were manufactured at least a couple of years ago).Here's what the problem looks like: when you first receive your power cover and attach it to your Surface Pro 2, the Surface Pro recognizes it, the keyboard functions as it should, and the battery status screen lists the charge as either 0% or 100%. However, it turns out that the Power Cover actually has an initial charge of 0% (this can be the case even when the power status shows a 100% charge). Here's why I think the problem occurs. Lithium Ion batteries usually have at least some kind of a charge inherent in them when you receive them, and when they're attached to a device. But, if the battery is old, it might have drained completely over the year or two it was sitting on a warehouse shelf. When someone buys a device (like a Power Cover) with a lithium ion battery that has no stored charge left in it, and then attaches it to a device, the device doesn't know what to do, and therefore it doesn't even attempt to charge the battery. In the case of the Power Cover and the Surface Pro 2, the Surface Pro doesn't quite know what to do, and so it mistakenly lists the status of the battery as being either 0% or 100%. But, there apparently is a way to "wake" up the battery so that the device finally recognizes it and begins charging it.Here's the solution that worked for me, and got my Power Cover to finally start charging:1) Attach your Power Cover to your Surface Pro 2 and check to see what charge is listed. If it lists either 0% or jumps up to 100% after a few seconds, that apparently is an indication that the Surface Pro is not yet recognizing the lithium battery. If that happens move to Step 2.2) Wait a few minutes and disconnect the power cover from your Surface Pro (note: leave the Surface Pro turned on with the AC adapter attached). Leave the Power Cover disconnected for a few minutes, and then reconnect it. Check the battery status bar (Note: to view the status of the batteries of the Surface Pro 2 and the Power Cover, click on the battery symbol at the bottom right section of the Task Bar at the bottom of the Surface Pro screen; Battery 1 is the Surface Pro's battery, and Battery 2 is the Power Cover's battery) , wait for it to process the fact that you just reattached the Power Cover, and see if it again lists 0% or jumps to 100%. If it remains at 0% check to see whether the status says "0% and charging". If it does not say that Battery 2 is charging, then repeat these steps: leave the power cover attached for a few minutes, then disconnect it and leave it disconnected for a couple of minutes, and then reattach it and check the status. Keep repeating these steps until the Power Cover's battery is recognized and actually begins charging (it took me several cycles of the above steps before it worked. I think the reason is that by doing these steps, a small amount of charge reaches the Power Cover's battery each time, and eventually it builds up enough of a small charge for the Surface Pro to recognize it's there and begins to charge it). I knew when my Surface Pro 2 got to this point because the status of Battery 2 stayed at 0%, but stated that the battery was charging. After a couple of minutes it went from 0% to 1%, and then kept increasing from there over the next couple of hours. Problem solved.Now that I was able to, finally, get the Power Cover to charge, I'm very pleased with it and feel comfortable rating it as 5 stars. It's nice knowing that I have a few extra hours of use before needing to plug my Surface Pro 2 in, and I also have a nice, responsive keyboard/cover as well.