Battery condition monitor and monitoring method

A battery condition monitor for a storage battery in an automotive vehicle connected to an alternator, the storage battery receiving and supplying currents having components of different frequencies, comprising:

• means for detecting a terminal voltage of the storage battery;
• first means for extracting voltage frequency components from the detected terminal voltage;
• means for detecting an amperage of the currents, one input of said amperage detecting means being connected to a terminal of the storage battery and another input of said amperage detecting means being connected to an output terminal of the alternator;
• second means for extracting amperage frequency components at the same frequencies as said voltage frequency components from the detected amperage;
• means for computing internal impedances of the storage battery at each of said frequencies from the voltage and amperage frequency components;
• means for storing predetermined relationships between the internal impedance, remaining capacity and remaining service life of the storage battery for each of said frequencies;
• and
• means for determining the remaining capacity and remaining service life values of the storage battery at said frequencies from the computed internal impedances and said predetermined relationships.

A method for monitoring the condition of a storage battery into and out of which currents flow, said currents having components of different frequencies, comprising the steps of:

• detecting a terminal voltage of the storage battery;
• detecting an amperage of the currents;
• extractng frequency components the detected terminal voltage and amperage signals at predetermined frequencies;
• computing internal impedances of the storage battery at said predetermined frequencies from the voltage and amperage frequency components;
• and
• determining the remaining capacity and remaining service life of the storage battery at said predetermined frequencies derived from the computed internal impedances, said determining step being carried out in accordance with predetermined relationships between the internal impedance, remaining capacity and remaining service life of the storage battery for each of said frequencies.