An other question you had about how long to charge a battery.
It depends on a charger.
We have a battery charger for the car, lawnmower etc.
It does not have a shut off button.
So if you you not turn it off, it can/will cook the battery.
He looked at the battery we use for the e-cig, and charge, when the green light comes on, it's done charging.
So no, no "cooking" of your e-cig
batteries if you leave them connected.
Same thing when you charge your
batteries for your camera.
I leave mine "charging" for weeks on end, they never "fry" because the charger has the "off" button.
When it turns green it's done.