If you look through your menus while it's charging it will give a capacity %. Once it hits 8.4v which is normaly about 90+% on my Hyperions it will maintain the 8.4v and continue to charge the last 10 or so percent, don't panic when you notice it doesn't stop charging at 8.4v. It's normal, you will also notice the charge amps will gradualy decrease after it reaches 8.4v, also normal.

Like others have said stopping the charge early won't hurt anything, many guys will pull it off once it hits 8.4v because they don't need that last few mah for racing.