BATTERY VOLTAGE DETECTOR

摘要

A battery power source device (20) is composed of a plurality of battery modules, each including a number of serially connected cells. Voltage detection circuits (13) are provided for each of the battery modules (19). Each voltage detection circuit (13) includes a differential amplifier (2) for detecting voltage across the end terminals of battery module, and the detected voltage is digitized and output through a photo-coupler (7) to a controller. The differential amplifier (2) is connected to the battery module (19) through photo-relays (5, 6), which are closed in response to an open/close control signal only during voltage detection, so that leak currents are eliminated. The differential amplifier (2) and the A/D converter (3) are provided with operating power obtained by transforming the voltage of the battery module (19) with regulators (11, 12), whereby noise effects are eliminated.