Battery-powered warning lamp e.g. for roadworks site - has standby battery which is substituted automatically by relay in low-voltage monitoring circuit

摘要

Closure of a main switch (Sch1) connects the main battery (31) to a 6V filament lamp bulb (32) via a flashing circuit (33) linked to a photoresistor (34) which detects the onset of darkness or fog, but can switched out (Sch2). A functional control unit (FKE) monitors the battery voltage, and when the lower limit is reached, operates a relay (104) to switch from the discharged battery (31) to a fully charged standby battery (36), and to activate an additional green LED (LD101). ADVANTAGE - Battery substitution as well as voltage monitoring is performed electronically to exclude human error.