Circuit for measuring battery current.

摘要

A current measuring circuit for measuring discharging current and charging current of a battery (10), which is selectively connected to a load (20) and a charger (21). The current measuring circuit comprises a resistor (RA) connected in series with the battery having a sufficiently low resistance value as not to substantially restrain the output current from the battery and a differential amplifier (1b) for amplifying a potential difference between both ends of the resistor. By providing a switch (8, 9) for short-circuiting one input terminal and the other input terminal of the differential amplifier, an offset/drift voltage of the differential amplifier can be obtained. This offset/drift voltage is used for correcting the output voltage from the differential amplifier at the time of current measurement and, thereby, the discharging current and charging current of the battery can be measured accurately. <IMAGE>