This is a minor question, really... but I bought a starter kit from Cignot and it comes with this carrying case that you charge, and the case in turn charges your batteries. My question is: Can I charge the case before it runs out of juice, or will that hurt the case's battery? I'm assuming it would be okay to charge, but I figured I'd be sure. If I'm gonna vape, I wanna get a good head start doing it the right way. 