Quote Originally Posted by Justloadit View Post
LiPo when reaching full charge, the current drops to approximately 1% of its capacity. The charger must then switch off completely, and not allow a trickle charge as is the case with other batteries.
These are usually built-into the battery as electronic safety features, or part of the phone's charging circuit, but sometimes it might be a feature of the charging transformer itself - it might be a good idea to have all 3 with such built-in safety "feature". The same stuff also ensures overheating shouldn't occur during use.

One thing noted in the tests: These electronic safety features (even from reputable manufacturers) are not fool proof, they're a stop-gap solution over the inherent dangers of the technology. Some circuits were fried due to static charges short-circuiting them (so don't wear nylon / other static collecting clothing), some got easily damaged due to mechanical shock (so don't drop the phone). So these safety features can easily fail even just because of normal daily use, thus make sure to treat the phone with care all the time.