I have several Smok V8 Stick Big Baby Beast vape pens and suddenly some of them won't charge. I got two brand new ones today, and when I plug the charger into the batteries, the red light comes on for few seconds, then goes off. Two of my older units just started doing that, too, and I have no idea what is causing it. The two other older ones charge just fine with the same chargers, so I am stumped.