There Should be a Chip in Phone and laptop batteries that simply disconnect the Battery from power source once it is fully charged. What I mean is that the software stack currently is able to recognize when the battery is fully charged. So why is that there cannot be a circuit breaker such that it would cut flow of the current to the battery? There should be an algorithmic way for the bios (software Stack) to simply turn off that switch once the battery charge has declined to a level like 10-20%. The intended purpose of such a feature would be to prevent your lithium ion battery from getting damaged by being always plugged in.