PURPOSE: To adequately protect a battery from generating overdischarge, by charging the battery in a state that a portable section is mounted on a main unit.
CONSTITUTION: An overdischarge protective-system consists of a main unit I provided with a charging equipment 1 and a current detecting resistor 14 placed between the charge terminala 2∼3, and a portable section II containing a battery 7 which can be charged, and worked with the power source of the battery. For example, the system is applied for the charging equipment of a cordless telephone unit or the like. While the battery 7 is charged, a switch circuit 10 is set in an ON-state by the control of a switch controlling circuit 9, and a working power source is fed to a load 8. When a charging power source is set in an interrupted state during the charging as it is, then current from the battery 7 is permitted to flow via said resistor 14, and by interrupting driving current to the switch controlling circuit 9, the switch circuit 10 is set in an OFF-state, and the battery 7 and the load 8 are separated from each other. As a result, during the charge interrupting period, the overdischarge of the battery 7 can be prevented from being generated via the load 8.
Ikegaya, Kenichi
Naito, Takao
Seshima, Yukio
Matsushima, Koji
