Ascertaining a charge state of a battery system that includes at least one battery cell and one additional energy store that is connected in series with the at least one battery cell and can be switched in and out. One method includes switching in the additional energy store; measuring a voltage of the additional energy store at predefined time intervals; ascertaining a capacity change of the additional energy store with reference to the measured voltage and to a characteristic voltage curve of the additional energy store; ascertaining a charge throughput of the additional energy store with reference to the ascertained capacity change of the additional energy store; and ascertaining the charge state of the battery system with reference to the ascertained charge throughput.

Ascertaining a charge state of a battery system that includes at least one battery cell and one additional energy store that is connected in series with the at least one battery cell and can be switched in and out. One method includes switching in the additional energy store; measuring a voltage of the additional energy store at predefined time intervals; ascertaining a capacity change of the additional energy store with reference to the measured voltage and to a characteristic voltage curve of the additional energy store; ascertaining a charge throughput of the additional energy store with reference to the ascertained capacity change of the additional energy store; and ascertaining the charge state of the battery system with reference to the ascertained charge throughput.

In a calculation system, a data acquisition unit is configured to acquire operation data of a battery, the operation data including at least voltages and currents measured by a management device at a plurality of time points, and states of charge (SOCs) estimated based on at least one of the voltages and the currents, the management device being configured to manage the battery. An extraction unit is configured to, extract, as sample data, a set of an SOC and a voltage from sets of the SOCs and the voltages the plurality of time points included in the operation data in a period in which the battery is regarded as resting, the period being specified based on the currents. An estimation unit is configured to estimate an SOC-open circuit voltage (OCV) characteristic of the battery based on the extracted sample data.

In a calculation system, a data acquisition unit is configured to acquire operation data of a battery, the operation data including at least voltages and currents measured by a management device at a plurality of time points, and states of charge (SOCs) estimated based on at least one of the voltages and the currents, the management device being configured to manage the battery. An extraction unit is configured to, extract, as sample data, a set of an SOC and a voltage from sets of the SOCs and the voltages the plurality of time points included in the operation data in a period in which the battery is regarded as resting, the period being specified based on the currents. An estimation unit is configured to estimate an SOC-open circuit voltage (OCV) characteristic of the battery based on the extracted sample data.

A processor-implemented method of estimating a state of a battery includes acquiring current information and voltage information of a battery; determining time interval values based on the acquired current information such that current integration values corresponding to the time variation values satisfy a condition; determining voltage values corresponding to the determined time interval values in the acquired voltage information; and determining state information of the battery based on the determined voltage values.

A processor-implemented method of estimating a state of a battery includes acquiring current information and voltage information of a battery; determining time interval values based on the acquired current information such that current integration values corresponding to the time variation values satisfy a condition; determining voltage values corresponding to the determined time interval values in the acquired voltage information; and determining state information of the battery based on the determined voltage values.

When a battery is insufficiently charged to allow ohmic testing of its condition, a charging source is connected to the battery, and a charge-acceptance test is performed to determine whether the battery is simply discharged but otherwise usable or beyond its useful service life.

When a battery is insufficiently charged to allow ohmic testing of its condition, a charging source is connected to the battery, and a charge-acceptance test is performed to determine whether the battery is simply discharged but otherwise usable or beyond its useful service life.

A system includes a state of charge (SOC) calculation module configured to calculate an SOC of a battery cell based on a measured current of the battery cell and an overpotential calculation module configured to receive the measured current and output lagged currents based on the measured current and respective time constants, output a weighted measured current and weighted lagged currents based on a plurality of weighting factors, wherein a sum of the plurality of weighting factors is 1, calculate an equivalent constant current corresponding to the measured current based on the weighted measured current and the weighted lag currents, and calculate an overpotential of the battery cell based on the equivalent constant current. The system is configured to output a predicted voltage of the battery cell based on the calculated SOC and the calculated overpotential of the battery cell.

A method for calculating a cell state includes: acquiring a first knee-point voltage threshold of a cell, a first knee-point electricity corresponding to the first knee-point voltage threshold, a second knee-point voltage threshold of the cell and a second knee-point electricity corresponding to the second knee-point voltage threshold; recording a first charging curve of the cell in real time; obtaining a target knee point according to the first charging curve, the first knee-point voltage threshold, and the second knee-point voltage threshold, and obtaining a target-knee-point electricity according to the first knee-point electricity or the second knee-point electricity; detecting the electricity of the cell until the charging is completed, and obtaining a charged electricity of the cell from the target knee point to the completion of charging; and obtaining the capacity of the cell according to the target-knee-point electricity and the charged electricity.