Method for the continuous measurement of the efficiency of a battery, especially a battery installed in motor vehicles, and a device utilizing this method

A device for continuous measurement of efficiency of a battery, the device being installed in a vehicle and being in electrical contact with the battery, by which it is powered, the device comprising:

• at least one temperature sensor and one voltage sensor;
• a predetermined and controlled resistive load;
• and
• processing circuitry configured to
• compute a state of charge SOC of the battery installed in the vehicle throughout both a key-off phase and a key-on phase, without a direct measurement of current, the computing being performed by progressively reading a battery voltage, both in absence and in presence of an electrical load and considering a time elapsed since a beginning of each discharge phase,
• determine a state of health SOH of the battery by applying a controlled current load and comparing a resulting voltage drop to predetermined parameters;
• determine a state of function SOF of the battery by estimating a residual autonomy that is a function of a discharge rate or current rate, and of an evolution of the SOC,
• correlate and normalize the SOC, SOH, and SOF based on an operating temperature of the battery, and
• store at least an initial SOC and SOH that are determined during the key-off phase.