Electricity meter for accumulator batteries

Claim 1

An electricity meter for an accumulator battery having an adding direction of operation corresponding to charging current flowing into the battery and a deducting direction of operation corresponding to discharging current flowing out of the battery comprising: a shunt, an amplification circuit connected to said shunt, an impulse generator connected to said amplification circuit for generating impulses having a frequency proportional to the current intensity on discharge or charge passing through said shunt, a device for counting and indicating the counted number of impulses, and threshold means and logic means coacting together for enabling the counting of said impulses in the adding direction only when the discharge current has an absolute value greater than a first pre-determined threshold value and enabling the counting of said impulses in the deducting direction only when the charging current has an absoLute value greater than a second pre-determined threshold value, a rectifier circuit connected between said impulse generator and amplification circuit and supplying at its output a voltage having the same polarity irrespective of the direction of the current in said shunt, an input circuit connected to the input of said amplification circuit and comprising two voltage dividers supplied with a stabilized voltage derived from said accumulator battery, a tapping on one of said voltage dividers being connected to an amplifier for producing a reference voltage under practically zero impedance, and the other of said voltage dividers having two arms in the lower arm of which is inserted said shunt.