I know its Nickel Metal meaning you can throw it on the charger whenever, as much as you want. But it is still recommended to kill the battery every now and then just to refresh it. I want to know how long I can leave it on the charger without having it over charge? Do Panasonic chargers have an option to turn off charging when its full? I dont think there is, as its still trickle charging, either way there is still some heat going to the battery. And how long do the batteries normally last before noticing the talk times start to shorten?