Method and apparatus for monitoring the state of charge of a battery

A method of monitoring the state of charge of a battery containing an electrolyte, which comprises:

• immersing at least one pair of test electrodes in the electrolyte;
• generating a test signal having a pulsed waveform, the pulsed waveform having a voltage which remains constant for a predetermined time sufficient to ensure that ion mobility in the electrolyte has reached a steady state velocity;
• applying the test signal to the at least one pair of test electrodes to thereby impress across the at least one pair of test electrodes an electromotive force of sufficient magnitude to cause ion movement in the electrolyte and a current to flow through the at least one pair of test electrodes and the electrolyte;
• and
• sensing the current flow through the at least one pair of test electrodes and the electrolyte caused by the electromotive force, the sensed current flow being indicative of the state of charge of the battery.

Apparatus for monitoring ion mobility in an electro-conductive fluid which comprises:

• at least one pair of test electrodes, the at least one pair of test electrodes being at least partially immersed in the electro-conductive fluid;
• a signal generator, the signal generator generating a test signal having a pulsed waveform, the pulsed waveform of the test signal having a voltage which remains constant for a predetermined time sufficient to ensure that ion mobility in the electro-conductive fluid has reached a steady state velocity, the at least one pair of test electrodes being responsive to the test signal, the test signal causing a current to flow through the at least one pair of test electrodes and the electro-conductive fluid;
• and
• means for sensing the current flow through the at least one pair of test electrodes and the electro-conductive fluid caused by the test signal, the sensed current being indicative of ion mobility in the electro-conductive fluid.