Battery voltage detector

A battery voltage detector that detects an output voltage of a connectable first DC power supply, comprising:

• voltage-dividing resistors that include at least a first resistor and a second resistor and divide the output voltage of the first DC power supply;
• a first switch that is electrically connected to the first resistor and the second resistor and includes a first terminal, a second terminal, and a control terminal;
• a second DC power supply that supplies a power voltage;
• a second switch that switches supply of the power voltage;
• a voltage comparator that includes a first and a second input terminals;
• a timer latch circuit electrically connected to the control terminal of the first switch that outputs a switching detection signal;
• a reference power supply that is electrically connected to the first input terminal of the voltage comparator and outputs a reference voltage;
• and
• a third switch that is electrically connected to the control terminal of the first switch and an output of the timer latch circuit that controls an input of the first switch based on the switching detection signal, wherein
• the first terminal of the first switch is electrically connected to the second input terminal of the voltage comparator,
• the control terminal of the first switch is electrically connected to a positive voltage side of the second DC power supply directly or via a resistor, and
• when the second DC power supply is supplied to the control terminal and when the third switch turns off, the first switch turns on and allows a voltage to be applied to the first and the second resistors.