Patent ID: 6417668
Filing Date: 2002-07-09
Classification: H02J

Abstract:
Apparatus for monitoring a battery having negative and positive terminals, comprising:a current sensor connected to a terminal of the battery for measuring current passing into and out of the battery; a voltmeter connected across the terminals of the battery for measuring battery voltage; a temperature sensor located near the battery for providing readings of ambient temperature; a data processing system receiving data from the current sensor, the voltmeter and the temperature sensor and including memory for the storage of programs and data; an engine starter system coupled for energization by the battery; a battery history table including records of battery condition during prior starts of the apparatus; an engine cranking power specification table: stored in the memory for providing an estimate of cranking power required to start an engine; a battery capacity table stored in the memory for providing estimates of battery capacity as a function of battery history, ambient temperature, open circuit voltage of the battery, voltage after a period T of cranking and current discharge during cranking; and a comparator utilizing the estimate of cranking power and an estimate of battery capacity as inputs to determine if battery capacity exceeds the cranking power estimate.