Philippe Poignant

Method of charging a lithium storage cell having a carbone anode

The present invention provides a method of charging a carbon-anode lithium storage cell, which method comprises a first step in which a constant current is imposed and during which the voltage across said storage cell is allowed to increase until it reaches a reference value, and then a second step in which said reference voltage is imposed and said current decreases. The method of the invention is characterized in that, at each instant, said reference voltage is equal to the sum of the end-of-charge voltage of the cell plus the product of the current multiplied by the ohmic resistance of the cell.

Method and apparatus for measuring the state of charge of an electrochemical cell pulse producing a high discharge current

The state of charge of an electrochemical storage unit is measured by applying to the electrochemical storage unit (32), a voltage pulse which is less than its nominal voltage, so as to make the storage unit deliver a high discharge current for a short period of time. The level of the voltage pulse is chosen to cause a discharge current that varies monotonically and preferably approximately linearly as a function of the state of charge of the storage unit, so that the state of charge can be unambiguously estimated by measuring the discharge current.

5519304 Circuit for measuring the state of charge of an electrochemical cell

The invention relates to a circuit for measuring the state of charge of an electrochemical cell that includes a parasitic resistance. The circuit comprises: means for subjecting the electrochemical cell to a refer ence voltage less than its nominal voltage, so as to cause it to deliver a discharge current; means for measuring the discharge current and providing an indication of the state of charge of the electrochemi cal cell; and correction means for correcting the reference voltage as a function of the discharge current, the correction means providing a corrected reference voltage that compen sates for the parasitic resistance. ABSTRACT