This 120 VAC to 12 VDC wall charging adapter plugs into standard wall outlet. It comes with an international plug kit used to either recharge a low battery or to use for continuous operation. The monitor has a built-in charging circuit that protects from overcharging. A completely discharged battery will be charged to capacity within ten hours. The battery will be drained slowly, even if the monitor is turned off. Therefore, if the monitor has not been charged for 7-10 days, the battery voltage will be low. The factory supplied battery is designed to last for ten hours of normal operation (no alarm, no back light condition). As the battery becomes older, or is subject to adverse conditions (such as cold ambient temperature), the battery capacity will be reduced significantly. Fits all PGM-50, 76, 2000, and 7000 series monitors.