Patent ID: 8466685

Claim:
A method of estimation of a state of charge of an alkaline battery having a predetermined nominal battery capacity C.sub.n, and comprising a reference electrode and a NiOOH positive plate, said method comprising: measuring a voltage between said positive plate and said reference electrode, said voltage being representative of the positive plate potential V.sub.+, and estimating the state of charge (SOC) as a function of said positive plate potential and of a battery current, wherein the method comprises: simultaneous measuring the battery current I, the positive plate potential V.sub.+ and a temperature T at a terminal of the battery, determining a temperature compensated value V.sub.c+ of the positive plate potential as a function of the measured values of the positive plate potential V.sub.+, of the current I, of the temperature T and of the nominal battery capacity C.sub.n, said estimation of the state of charge taking into account the temperature compensated value V.sub.c+ of the positive plate potential, wherein said determination of the temperature compensated value V.sub.c+ of the positive plate potential comprises the following steps: determining a temperature coefficient k.sub.tsoc corresponding to at least one charge or discharge rate, calculating the compensated value V.sub.c+ of the positive plate potential according to V.sub.c+=V.sub.++(T−T.sub. 0 ).times.k.sub.tsoc, wherein T.sub. 0 is a predetermined reference temperature.