Battery measurement method and apparatus for complex impedance measurement

A battery measurement method to be carried out by a battery measurement apparatus for measuring a state of a rechargeable battery, the battery measurement method comprising:

• a performing step of performing one of:
• a first task of causing the rechargeable battery to output a composite wave signal that is combination of at least first and second alternating signals, the first and second alternating signals respectively having first and second frequencies different from one another;
• and
• a second task of causing the first and second alternating signals to be inputted to the rechargeable battery as the composite wave signal;
• a measuring step of measuring a voltage variation across the rechargeable battery in response to the composite wave signal;
• and
• a calculating step of analyzing, for each of the first and second frequencies, the voltage variation in accordance with the first and second alternating signals and the voltage variation to accordingly calculate information on a complex impedance of the rechargeable battery,
• wherein:
• the performing step further includes:
• setting a predetermined wavenumber of each of the first and second alternating signals;
• determining whether an input or an output of the predetermined wavenumber of one of the first and second alternating signals to or from the rechargeable battery has completed;
• switching, in response to determination that the input or output of the predetermined wavenumber of one of the first and second alternating signals to or from the rechargeable battery has completed, the completed one of the first and second alternating signals to a new alternating signal having another frequency while continuing the input or output of the other of the first and second alternating signals to or from the rechargeable battery.