Power distribution terminal storage battery undervoltage on-line monitoring device and method

The invention discloses a power distribution terminal storage battery undervoltage on-line monitoring device and method. The device comprises an alternating current power supply contact module, an open-circuit voltage monitoring relay module and an operation module. The open-circuit voltage monitoring relay module comprises an alternating-current time delay relay, an alternating-current power-loss blocking relay, a local starting relay, a detection execution relay and a direct-current under-voltage relay. The method comprises the following steps: selecting an automatic or manual monitoring function through an operation module; when the automatic monitoring function is selected, an action switch of the alternating current delay relay is closed after preset time, or when the manual monitoring function is selected, an action switch of the on-site starting relay is closed; an action switch of the detection execution relay is switched off, and an open circuit breakpoint is formed in a loop of the direct-current ch