Hello, I just read about this on another thread. It would appear that is has a built in battery tender, if so, this is a good thing. Basically, when charging the battery, it will charge to 100% then turn off the charger until the charge held by the battery reduces to a predetermined amount. At that point it begins charging again. If you charge it with the phone off, it will charge to 100% then simply stop, since the phone is off,it does not cycle , thus still 100%. Unplugging a turned on phone (that is not registering 100%) and then plugging it back in, restarts the cycle. This whole process protects the battery.