Sounds then like it was discharged. Long hours at high wattage, which is what you have at 4 volts on the 1.8 coil, will drain most batteries in less than the "average" time.
I generally don't recommend charging unattended, or asleep. While rare, considering all the batteries in use, a catastrophic failure in the charger or battery (or wall wart for the charger) can be dealt with more quickly if awake than if the smoke alarm gets you up.
You really should have at least two, anyway. One to use while the other charges. And in case of a failure or breakage.
Murphy was an optimist.
What he said! ^
And please get a quality name brand battery this time; joyetech eGo-C Twist, Vision Spinner, Kanger eVod VV, Smoktech Winder are all good. And buy from a reputable vendor who exchange or replace a bad battery.
Good luck!
