This week a friend said he was put off purchasing an Apple Pencil because you can never tell how charged up it is, I said the concern should be the cost, I do like the Pencil, but I still think this is too expensive.
With Notification center it will show you an alert when it is low and needs charging, but you can check at any time.
All you need to do with your iPad is swipe right so you see the notification center, as long as you have the battery widget enabled then it will show you how much battery you have left in the pencil as well as the iPad.
I am always interested in feedback so please feel free to add any comments, or you can mail me here. If you would like to submit a quick tip with full credit and links back to your site then also feel free to contact me.