Battery module voltage detector

A battery module voltage detector that detects a voltage of each of battery modules, wherein each battery module including one cell or more, and M battery modules are connected in series as a battery pack, and “M” is a positive integer, the battery module voltage detector comprising:

• (M+1) voltage detecting terminals connected to a positive electrode of a battery module having a highest potential, a negative electrode of a battery module having a lowest potential, and (M−1) connecting points between the battery modules adjacent to each other, respectively;
• a filter circuit having input terminals which are connected to the voltage detecting terminals, respectively;
• switching circuits having input terminals which are connected to output terminals of the filter circuit, respectively;
• and
• a voltage detecting circuit connected to output terminals of the switching circuit to detect the voltage of each battery module, wherein
• the filter circuit includes a resistor-and-capacitor arrangement including resistors that are connected between the input terminals and the output terminals of the filter circuit, respectively, and capacitors that are connected between output terminals of the filter circuit, respectively, to have a characteristic of a low-pass filter, and wherein
• the resistor-and-capacitor configuration of the low-pass filter is determined by adjusting a resistance value and position of the resistor in the resistor-and-capacitor arrangement as well as capacitance and position of the capacitor in the resistor-and-capacitor arrangement, so that frequency response is kept constant when the voltage of the plurality of battery modules is detected.