A method of determining battery degradation retroactively using historical data is disclosed. The method includes the steps of collecting state of charge (SOC) and DC ampere data for a predetermined time period; determining a delta (Δ) SOC based on the data collected; creating a set of SOC regimes having a size based on ΔSOC; filtering the SOC data and determining a set of points which indicate a charging or discharging event; and calculating overall Coulombs associated with each charging or discharging event and for each event, producing a timestamp and Coulombs associated with each event.

The invention relates to an energy storage comprising a plurality of series connectable energy modules connected to a string via a plurality of switches. Wherein a string controller controls which of the energy modules that are part of a current path through the string by control of the status of the switches. An energy storage monitoring system is monitoring an energy storage element operating parameter of an energy module, the energy storage monitoring system comprises: a current sensor and a plurality of energy module print. The plurality of energy module prints establishes an energy module operating parameter of the associated energy module. The current sensor establishes the current in the current path. The string controller is configured for by-passing an energy module based on information of status of the switches, the measured current in the current path and the battery operating parameter measured at the energy modules.

A battery monitoring device according to an embodiment monitors a state of a secondary battery block including parallel cell blocks connected in series each of which includes battery cells connected in parallel. A calculator calculates direct-current internal resistance values of the parallel cell blocks based on a differential current between first and second current values detected by a current detector, voltages of the parallel cell blocks corresponding to the first and second current values detected by a voltage detector. A determiner performs anomaly determination for the parallel cell blocks from the direct-current internal resistance values of the parallel cell blocks and a maximum value of the direct-current internal resistance values of the parallel cell blocks.

A battery monitoring device according to an embodiment monitors a state of a secondary battery block including parallel cell blocks connected in series each of which includes battery cells connected in parallel. A calculator calculates direct-current internal resistance values of the parallel cell blocks based on a differential current between first and second current values detected by a current detector, voltages of the parallel cell blocks corresponding to the first and second current values detected by a voltage detector. A determiner performs anomaly determination for the parallel cell blocks from the direct-current internal resistance values of the parallel cell blocks and a maximum value of the direct-current internal resistance values of the parallel cell blocks.

A method of controlling a battery including a first control circuit and a plurality of modules arranged between first and second terminals. Each module comprises electric cells. The battery further includes a sensor of the current flowing through the first terminal. The method includes the successive steps of: updating a first counter representative of the quantity of charges flowing through the first terminal; for each electric cell, for each connection of the electric cell to the other electric cells, storing into first data the value of the first counter on connection of the electric cell and for each disconnection of the electric cell from the other electric cells, storing a second counter equal to the difference between the value of the first counter on disconnection of the electric cell and the first data of said electric cell.

A method of controlling a battery including a first control circuit and a plurality of modules arranged between first and second terminals. Each module comprises electric cells. The battery further includes a sensor of the current flowing through the first terminal. The method includes the successive steps of: updating a first counter representative of the quantity of charges flowing through the first terminal; for each electric cell, for each connection of the electric cell to the other electric cells, storing into first data the value of the first counter on connection of the electric cell and for each disconnection of the electric cell from the other electric cells, storing a second counter equal to the difference between the value of the first counter on disconnection of the electric cell and the first data of said electric cell.

A method for battery capacity estimation is provided. The method includes monitoring a sensor, collecting a plurality of data points including a voltage-based state of charge value and an integrated current value, defining within the data points a first data set collected during a first time period and a second data set collected during a second time period, determining an integrated current error related to the second data set, comparing the integrated current error related to the second data set to a threshold integrated current error. When the error related to the second data set exceeds the threshold, the method further includes resetting the second data set based upon an integrated current value from the first time period. The method further includes combining the data sets to create a combined data set and determining a voltage slope capacity estimate as a change in integrated current versus voltage-based state of charge.

A storage battery control device for controlling an energy storage system including storage batteries connected in series, bypass units that bypass the storage batteries respectively, and a current sensor that detects a charge and discharge current flowing from or into the storage batteries. Each of the bypass units includes a bypass line that bypasses the storage battery, a bypass switch that connects and cuts off the bypass line, and a cutoff switch that connects and cuts off the storage battery. The storage battery control device is configured to detect a zero current state in a case that both the bypass switch and the cutoff switch are in a cutoff state in at least one of the bypass units, and perform offset correction of the current sensor based on an output of the current sensor when the zero current state is detected.

A storage battery control device for controlling an energy storage system including storage batteries connected in series, bypass units that bypass the storage batteries respectively, and a current sensor that detects a charge and discharge current flowing from or into the storage batteries. Each of the bypass units includes a bypass line that bypasses the storage battery, a bypass switch that connects and cuts off the bypass line, and a cutoff switch that connects and cuts off the storage battery. The storage battery control device is configured to detect a zero current state in a case that both the bypass switch and the cutoff switch are in a cutoff state in at least one of the bypass units, and perform offset correction of the current sensor based on an output of the current sensor when the zero current state is detected.

Provided are a battery management system (BMS) and a battery system capable of accurately measuring a voltage without using a precise resistance element and reducing an error even when operating in a wide temperature range. Since a correction amount for the resistor included in the voltage measurement module is generated using a diagnostic power source configured independently of the battery system, and a voltage of the circuit included in the battery system is measured by applying the generated correction amount, the voltage may be precisely measured without using a high-precision resistance element. Since a changeover switch operates periodically to generate and apply an updated correction amount according to a changing environment, the voltage may be precisely measured even if it is applied to a system in which the environment continuously changes, such as a driving electric vehicle.