100mah= about an hr of moderate vaping. So a 650mah battery should be about 6-7hrs. Anyone who says their getting 20+hrs on one battery is a very light vapor.
And like other posts said, certain things will change that number like using LR attys/cartos which will drain the battery faster, ect.
Deback, your question earlier about the voltage difference from the 650mah, 900mah, 1000mah batteries is they are all the same, 3.3-3.4V. All eGos are 3.3-3.4V, the different mah is just how long the battery lasts.
As far as chargers, I have no idea if some batteries arnt fully charged when the light turns green. I dont use eGos because I prefer 3.7V PVs more than 3.3-3.4V eGos, but I use a PV that uses non-proprietary batteries and have checked them on a multimeter after the light turns green and they are fully charged, but that doesnt mean all batteries do that.
I would be careful of leaving a battery on a charger for long periods of time after the light turns green. MOST chargers have a chip in them that will stop charging a battery when it is full, or switch to a trickle charge, but not all. What you have to be careful about though is that the charger is working properly. If that chip fails in a charger, it will continue charging the battery after its already full. Thats can be very dangerous. Most stories you hear about batteries exploding, catching fire, etc are because the chip failed in the charger that is supposed to stop charging the battery when its fully charged. Thats why I dont recommend leaving a battery on a charger for a long time after the light turns green, or letting batteries charge overnight.
Better to be safe than sorry.