BATTERY STATE JUDGING DEVICE

摘要

The present invention provides a battery state determining apparatus which can determine a battery state of a lead battery from an engine starting voltage accurately considering influence of a temperature of a vehicle. An engine starting voltage Vst1 obtained by correcting an engine starting voltage Vst of a lead battery at an engine starting time is calculated based upon an open-circuit voltage OCV and a temperature of a vehicle(S112), a battery determination voltage Vst_th representing a voltage of the lead battery at an engine starting time when a growth rate of internal resistance of the lead battery reaches a predetermined value from the open-circuit voltage OCV is calculated (S126), and a battery state of the lead battery is determined by determining whether an engine starting voltage Vst1 belongs to a predetermined region on a characteristic map (S132). A temperature of the lead battery measured after at least a predetermined time elapsing from engine stopping is regarded as temperature of the vehicle so that the engine starting voltage Vst1 is calculated.