Saft-Societe Des Accumulateurs Fixes Et De Traction

Pierre Belot

Eric Patry

Monitoring the state of charge consists of providing a magnitude g (e.g. a frequency F1) which is proportional to the storage battery charging or discharge current I (sensed at 2) and of algebraically integrating said magnitude (e.g. in an up/down counter K4, K5) into data which is the image of the state of charge of the storage battery; the proportionality constant a=g/I between said magnitude and said current being given a lower value during charging than during discharging, and the value of the constant a being varied during charging as an increasing function of the current I.

Method and device for monitoring the state of charge of a storage battery

A device for controlling the charging of a storage battery includes two counters (IC1, IC2) measure a minimum discharge time and a maximum charging time and are controlled by means of logic gates (2, 3) according to whether the main current is supplied or not. The device has application to maintaining a battery permanently charged despite interruptions in the mains current supply.

Device for controlling the charging of a storage battery

After a cell has discharged a quantity Q.sub.o of electricity, charging is controlled by measuring the quantity k Q.sub.o of electricity supplied to the cell, where k is the recharging coefficient and greater than 1. The value of k is varied as an increasing function of the quantity Q.sub.o of electricity discharged, in other words as an increasing function of the relative depth of discharge Q.sub.o /C of the storage cell, where C is its capacity. The state of charge is monitored by generating a magnitude g which is a function of the charging or discharging current. This is done by algebraically integrating the current I over time while using scaling coefficients a=g/I of different values during charging and during discharging. The value of a is varied during charging so that its average value over a complete recharging operation is a decreasing function of the initial depth of discharge from which the recharging operation starts recharging.

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Pavillons sous bois, France

Pierre Belot