Hi. I have a new Joye ego (just bought one battery and a low resistance atomizer). I purchased the "fast charger" for it, and it seems to take forever for the green light to change to red. It only stays on red for around 20mins and then goes back to green. The battery is not fully charged and will only last 40mins or so of decent vaping before going flat. Can I use my normal 510 charger to charge the Ego? I understand it will take a long time to charge. What could be wrong with the fast charger? Thanks