When i put the battery in on full charge it will start at 4.2. It wont be long before it drops, i haven't been vaping hard lately. About half a day and it will be around 3.8 3.6, and i notice it because i am getting a lot less vapor. Put a full charged batt in and lots of vapor. Seems right, but i thought somewhere i heard that they maintain a lvl of power until it dies. I normally vape at 4.2. Any thoughts?