Abstract: According to an aspect, a battery system includes a current sensor configured to measure a current that charges or discharges a battery, a voltage monitor configured to measure a cell voltage of the battery, a state-of-charge (SoC) calculation engine configured to calculate an SoC value, and an energy calculation engine configured to compute charge energy loss of the battery for a sampling period based on the current, cell voltage, and the SoC value and compute a capacity degradation metric based on the charge energy loss and reference charge loss of a reference battery. The energy calculation engine is configured to transmit, via an interface, the capacity degradation metric to a battery manager of a device.

Abstract: A method for determining an ageing parameter KSOH of a rechargeable battery, especially a lithium rechargeable battery, featuring the steps (a) detecting an impedance Z of the rechargeable battery at different frequencies f, so that a Nyquist plot and a real part path, which plots a real part of the impedance Z against the frequency f, are obtained, determining at least one of the following SOH parameters, which can be selected from a predetermined list, establishing an SOH row vector {right arrow over (PSOH)} from the SOH parameters and all mixed terms of the form pSOH,m·pSOH,n, m=1, . . . , 11, n=1, . . . , m. The invention provides for the multiplication of the SOH row vector {right arrow over (PSOH)} by a saved calibration vector {right arrow over (ASOH)}, thereby obtaining the ageing parameter KSOH.

Abstract: An inhalation component generation device includes a load configured to vaporize or atomize an inhalation component source with electric power from a power supply, a notification unit, and a control unit configured to acquire a value indicating a remaining amount of the power supply and acquire an operation request signal to the load to generate a command for operating the load. The control unit is configured to cause the notification unit to perform second notification when the value indicating the remaining amount of the power supply is less than a first threshold and equal to or more than a second threshold smaller than the first threshold. The control unit is configured to cause the notification unit to perform third notification when the value indicating the remaining amount of the power supply is less than the second threshold. The first threshold is changeable based on an algorithm.

Abstract: A parameter estimation device configured to estimate a parameter of an equivalent circuit model of a secondary battery includes: a voltage acquisition unit configured to acquire a voltage of the secondary battery in a time-series manner; a current acquisition unit configured to acquire a charge/discharge current of the secondary battery in a time-series manner; an estimation unit configured to estimate the parameter on the basis of the voltage acquired by the voltage acquisition unit and the charge/discharge current acquired by the current acquisition unit; and a prohibition unit configured to prohibit the estimation of the parameter performed by the estimation unit, on the basis of the charge/discharge current acquired by the current acquisition unit or the voltage acquired by the voltage acquisition unit.

Abstract: An on-line State of Health estimation method of a battery in a wide temperature range based on “standardized temperature” includes: calculating battery Incremental Capacity curve of a battery, establishing a quantitative relationship between the voltage shift of the temperature-sensitive feature point and the temperature of a standard battery, standardized transformation of Incremental Capacity curves at different temperatures, establishing a quantitative relationship between the transformed height of the capacity-sensitive feature point and the State of Health based on a BOX-COX transformation. The BOX-COX transformation is expressed as y k ( ? ) = { y k ? - 1 ? ? ? 0 ln ? ? y k ? = 0 . An maximum likelihood function is used to calculate the optimal ?, and the transformed height of the capacity-sensitive feature point y can be acquired.

Abstract: A method includes obtaining data indicating an amount of energy stored by a battery of a sensor device; receiving data related to at least one condition in an area in which the sensor device is located; determining a reporting interval based on the data indicating the amount of energy stored by the battery of the sensor device and the data related to at least one condition in the area in which the sensor device is located; transmitting data indicating the reporting interval to the sensor device; and receiving a plurality of measurement reports transmitted from the sensor device according to the reporting interval. The energy consumed by the sensor device can be dynamically modified by dynamically modifying the reporting interval.

Abstract: A degradation estimating device includes: an acquiring unit that acquires time-series data of an SOC in an energy storage device; and an estimating unit that estimates degradation of the energy storage device based on a fluctuation magnitude of the SOC in the time-series data acquired by the acquiring unit. The degradation estimating method of an energy storage device acquires time-series data of an SOC in the energy storage device, and estimates the degradation of the energy storage device based on a fluctuation magnitude of the SOC in the acquired time-series data.

Abstract: A processor-implemented battery management method includes: estimating state information of a plurality of battery cells in a battery pack using a first battery state estimation model; determining whether state information of at least one of the plurality of battery cells is to be estimated using a second battery state estimation model; and estimating the state information of the at least one battery cell using the second model, in response to a result of the determining being that the state information of the at least one battery cell is to be estimated using the second model.

Abstract: A CMOS analog sensor interface circuit embedded in a passive RFID platform can provide accurate data conversion from analog signals to their digital representations. This interface can also utilize the RFID platform to achieve wireless data transmission. The disclosed sensor interface circuit includes signal filtering, signal amplification, as well as signal digitization. These circuits are all designed under the constraints of low-power operation on a noisy silicon substrate. By using the disclosed circuit design, fully passive wireless sensing network that can integrate with heterogeneous sensors (resistance, voltage, current types) can be designed. The advantages of low-cost, small feature size, and the ability to interface with analog sensors can enable large-scale deployment of such kind of RFIDs, both for consumer electronics like in-door monitoring and industrial sensing applications like the grid, electric vehicle, motor, and other critical infrastructures.

Abstract: Various embodiments of the present technology may provide methods and apparatus for a battery. The apparatus may determine a first current according to a first technique and a second current according to a second technique. The apparatus may use a Kalman filter to compute the state of charge of the battery, wherein the Kalman filter uses one of the first current and the second current based on a comparison of the second current to a threshold current.

Abstract: A battery management system for determining a time series of normalised voltage of at least one battery cell corresponding to a time period during which a first current flows through the at least one battery cell.

Abstract: A method for establishing visual images of models of battery status transforms data of one or more characteristic parameters collected in a period of time into multiple images composed by normalized pixels corresponding to the data. The multiple images are superimposed with one another to form variant image(s) with variant areas and further moving trends of the variant areas. The visualization of data and superimposition of the visualized images facilitates correlation and variation analysis among characteristic parameters of the battery module. The present invention transform data analysis to image analysis, and therefore, the present invention facilitates following analysis and model training, which can adapt to environmental changes, and indicate battery status and battery events efficiently and accurately.

Abstract: A system for managing a battery of a vehicle includes a battery, a main relay connected to the battery to transfer or block power of the battery to components in the vehicle, and a controller. The controller is configured to control the components in the vehicle to be in a power-off (IG OFF) state and turning off the main relay when receiving a vehicle power-off input, and to determine whether or not the battery is abnormal by calculating a parameter for determining a state of the battery and comparing the calculated parameter with a plurality of reference values that are preset.

Abstract: The present invention relates to an apparatus and a method for diagnosing a battery, and comprises: a power conversion unit for discharging and charging a battery; and a control unit for controlling the power conversion unit to discharge and charge the battery, and diagnosing power fade of the battery by calculating a maximum discharge output and a maximum charge output of the battery on the basis of a voltage and a current of the battery measured during discharging and charging of the battery.

Abstract: A battery pack includes cell units in which upper and lower battery cells are connected in series, wherein an output of series-connection and an output of parallel-connection can be switched. The cell units are respectively provided with protection circuit ICs for monitoring the state of the battery cells, and only the protection circuit on the lower cell unit side is provided with a controller 350 including a microcomputer. To adjust the power consumption for the microcomputer only provided in the lower cell unit, the circuit on the upper cell unit side is provided with a current consumption control means including dummy loads. The current consumption control means is operated in conjunction with the start-up of the microcomputer in the controller so as to equalize power consumption on the upper cell unit side and the lower cell unit side.

Abstract: A method and apparatus for correcting a state of charge (SOC) is provided. The method includes: acquiring state data of a battery cell in a case where the battery cell meets a preset standing condition, wherein the state data includes: current and voltage data, the preset standing condition is that the current in the state data is less than a preset current threshold, wherein a length of the voltage data in the state data is greater than a preset length; calculating an estimated steady-state Open Circuit Voltage (OCV) value according to the state data, under a condition that a change value of the voltage data in the state data is greater than a preset change threshold; determining a SOC correction value corresponding to the estimated steady-state OCV value; and correcting a current SOC by using the SOC correction value corresponding to the estimated steady-state OCV value.

Abstract: A printing apparatus includes: a battery accommodating portion; a conveyor; a printing device; a power-source connector; an electric charger that charges the battery power source from an external power source when the power-source connector is connected to the external power source; and a degradation-degree detector that detects a degradation degree of the battery power source. A controller executes: a charge processing for controlling the electric charger using at least one charge parameter to charge the battery power source; storing data on the degradation degree of the battery power source based on a result of detection of the degradation-degree detector; a determining processing for determining whether a particular determination criterion relating to the degradation degree is satisfied in the stored data; and correcting the at least one charge parameter in accordance with a result of determination in the determining processing.

Abstract: An uninterruptible power system (UPS) testing method includes the steps of setting an operational decline table, setting an initial value, collecting data, inputting targets, executing multi-algorithm, and indicating a warning or an approval. Wherein, battery cells of the UPS are repeatedly tested when being actually used at different temperatures to set the operational decline table and the initial time value; and data about temperatures and time periods of the battery in operation are continuously collected for a user to execute algorithms based on designated conditions to predict the battery state in a future time period; and an indication message is generated for the user to determine whether the battery is still usable or has to be replaced. In this manner, it is able to estimate the running time of a target time of the UPS without the need of performing an actual electrical discharge procedure.

Abstract: A system for state determination of a battery module configured for use in an electric vehicle. The system including a battery module including at least a battery cell, a sensor including a proximity sensor configured to detect a status datum corresponding to the battery module, a processor configured to receive the status datum from the sensor, generate a charge datum as a function of the status datum corresponding to the battery module, generate a health datum as a function of the status datum corresponding to the battery module, transmit the charge datum and the health datum, and a display configured to receive the charge datum and the health datum corresponding to the battery cell, and display the charge datum and the health datum corresponding to the battery cell.

Abstract: A battery deterioration judging system includes a memory, and a processor coupled to the memory. The processor is configured to acquire a state amount of a battery, derive a first deterioration probability of the battery, based on the state amount of the battery and a predetermined first calculation model, derive a reliability degree of a second calculation model, which is different than the first calculation model, based on a number of state amounts, derive a second deterioration probability of the battery, based on the state amount of the battery and the second calculation model, and judge deterioration of the battery based on the reliability degree, and at least one of the first deterioration probability or the second deterioration probability.

Abstract: Battery management systems and methods for use with lithium-ion batteries that employ silicon-based negative electrodes. The battery management systems and methods consider the lithiation/delithiation properties of silicon-based anode materials by considering voltage relaxation behavior. The battery management systems and methods may also be applied to other materials that similarly display an apparent hysteresis in the lithiation/delithiation processes and/or form multiple phases with different electrochemical properties.

Abstract: A protection and monitoring system, device, and method for an electric power system, including a capacitor bank having multiple strings in each phase, voltage and current measuring devices, and relays to protect this capacitor bank. Each string can have multiple capacitor units and each unit can consist of multiple capacitor elements. The method may include: determining steady state operating condition using the obtained current and voltages, calculating and storing present time impedance value of each string into memory, calculating the string per unit impedance incremental quantity, detecting capacitor element failure based at least in part on this incremental quantity and calculating number of failed capacitor elements for each event, accumulating the number of failed capacitor elements, and performing a protection action when healthy capacitor elements are subject to an overvoltage limit.

Abstract: A method for evaluating a state of health (SOH) of an electric battery of an electric vehicle, said method comprising a step of: performing a given number (m) of tests on the electric battery, each giving results, associating each result to a state of the battery, a given number (N) of states of the battery being possible, estimating a probability of each state of the battery on the basis of a Bayesian calculation, and estimating the SOH in function of the probability of each state and of the results of the tests, called estimated SOH.

Abstract: The present invention discloses a method for rapidly estimating for a remaining capacity of a battery, comprising performing a constant current charge to the battery in a first period, instantly capturing a voltage/temperature of the battery in a frequency, and generating a voltage-time graph; after leaving the battery along for a second period, instantly capturing the voltage/temperature of the battery in the frequency; calculating a voltage rising rate during the first period; calculating a voltage drop rate during a leaving-along period; calculating a critical sample time; applying the critical sample time, and comparing the voltage-time graph measured in the first period, to obtain a critical sampling voltage; calculating a voltage difference slope; calculating a charging time, which is consumed by charging the battery from a lower-bound voltage to an upper-bound voltage with the constant current; calculating a compensation ratio value; and calculating the remaining capacity of the battery.

Abstract: A system includes a first group of sensors and a control circuit including one or more processors. The first group of sensors is associated with an energy storage module having one or more energy storage devices. The sensors in the first group generate sensor measurements representing one or more parameters of the energy storage module. The control circuit is configured to receive the sensor measurements and determine one or more of a reference value or a reference variation of a specific parameter related to the energy storage module based at least in part on the sensor measurements. The control circuit compares one or more of monitored values or monitored variations of the specific parameter, based on the sensor measurements generated by sensors, to the reference value or the reference variation of the specific parameter and detects a deviation that is greater than a designated tolerance margin.

Abstract: A direct-current voltage supply circuit includes a first field effect transistor in a power line, a voltage divider including a first fixed resistor and a positive temperature coefficient thermistor between the power line and a ground line, a thyristor connected at an anode thereof to the power line, with a second field effect transistor interposed therebetween, connected at a gate thereof to a node in the voltage divider, and connected at a cathode thereof to the ground line, with a second fixed resistor interposed therebetween, and a third fixed resistor connected in parallel with the thyristor and the second field effect transistor. If abnormal heating increases the resistance of the positive temperature coefficient thermistor, the first field effect transistor is turned off and the supply of direct-current voltage is stopped.

Abstract: A managing device calculates a whole state of power (SOP) that is an SOP of a whole of the plurality of power storage blocks based on SOPs of the respective power storage blocks and currents flowing through the respective power storage blocks, and sets an upper limit value of power or a current for at least one of charging and discharging by a power converter, based on the whole SOP thus calculated. The managing device estimates a current flowing through each of the power storage blocks from a voltage and an internal resistances of each of the power storage blocks before the power converter starts power conversion.

Abstract: An electric construction machine is provided that can travel from a work location to a charging location, and can suppress deterioration of work efficiency. The electric hydraulic excavator includes: a battery device (19); an electric motor (28) that is driven by power of the battery device (19); a hydraulic pump (29) that is driven by the electric motor (28); a travelling hydraulic motor (7) and a work hydraulic actuator that are driven by a hydraulic fluid delivered from the hydraulic pump (29); a controller (37); and a display device (24).

Abstract: A battery monitoring apparatus acquires a first physical quantity detected by a first detecting unit, and acquires a second physical quantity detected by a second detecting unit at each predetermined detection period. The battery monitoring apparatus stores the acquired first physical quantity and the acquired second physical quantity in association with respective time parameters. The time parameter is a time of detection of the respective first or second physical quantity or a correlation value that is correlated with the time of detection of the respective first or second physical quantity. The battery monitoring apparatus monitors a state of a storage battery using a set of first physical quantity and second physical quantity of which a difference in the time of detection is shorter than the detection period, among the first physical quantities and the second physical quantities stored by the battery monitoring apparatus, based on the time parameters.

Abstract: A method of estimating a maximum power limit of a battery cell at a specified prediction time using an improved RC equivalent circuit battery model and based on the battery cell's state of charge (SOC), temperature, and state of health (SOH). The method includes determining the battery cell's peak and continuous current limits, predicting a peak voltage after the specified prediction time based on the peak current limit, determining buffer values for the predicted peak voltage and the temperature of various battery components, setting a maximum current limit based on the buffer values, predicting a maximum voltage after the specified prediction time based on the maximum current limit, and determining a maximum power limit based on the predicted maximum voltage and the maximum current limit.

Abstract: A method of estimating a state of an energy storage system of a vehicle, in particular for estimating an aging state of the energy storage system, includes the following steps: acquiring information about the energy storage system; analyzing the acquired information while taking into account specified boundary conditions; and estimating the state of the energy storage system.

Abstract: In response to demands for stably and precisely estimating states, a rechargeable battery state estimation device includes a current detecting unit which detects a charge-discharge current of the rechargeable battery as a detected current; a voltage detecting unit which detects a voltage between terminals of the rechargeable battery as a detected voltage; an OCV estimation method SOC estimation unit which calculates an OCV estimation method state of charge, based on the detected current and the detected voltage; a current integration method parameter estimation unit which estimates a current integration method parameter including a capacity retention rate, based on the detected current and the OCV estimation method state of charge; and a corrected SOC estimation unit which calculates an estimated state of charge, based on the detected current, the OCV estimation method state of charge, and the current integration method parameter.

Abstract: An information handling system includes power inputs, a battery, a BMC, a memory, and a processor. The BMC determines which of the power inputs are coupled to associated power sources, and a first duration of time that the battery can provide power to the information handling system. The memory stores a firmware element. The processor receives a firmware that includes a second indication as to which of the power inputs are to be coupled to their associated power source as a condition for saving the firmware update, and that includes a second duration of time that it is expected to take to save the firmware update. The information handling system saves the firmware update to the memory when the first indication matches the second indication and when the first duration of time is greater than the second duration of time.

Abstract: A method for battery capacity estimation is provided. The method includes, within a computerized processor, monitoring a sensor operable to gather data regarding a battery, determining a voltage-based state of charge for the battery based upon the data from the sensor, determining a capacity degradation value for the battery based upon the data from the sensor, determining an integrated current value through Coulomb counting based upon the data from the sensor, determining a predicted battery state of charge for the battery based upon the capacity degradation value and the integrated current value, processing the voltage-based state of charge and the predicted battery state of charge using a Kalman filter to generate an updated overall battery capacity estimate, and using the updated overall battery capacity estimate to control management of the battery.

Abstract: An electronic assembly includes a board and a system mounted to the board. The system includes an impedance matching circuit coupled to a contactless component. A detection circuit operates to carrying out a process for detecting on the board of potential faults in the system mounted to the board. The detection circuit includes a circuit incorporated into the contactless component itself and configured to carrying out a first part of the process for detecting. A processing circuit of the detection circuit performs a second part of the process for detecting based on results of the first part.

Abstract: According to one embodiment, an evaluation device for an energy storage device includes first processing circuitry and second processing circuitry. The first processing circuitry acquires data items including an amount of charge and a voltage value measured in a measurement period from the energy storage device, the energy storage device being charge-discharge-controlled according to charge-discharge command values. The second processing circuitry generates a representative data item of voltage values for amounts of charge, based on the data items acquired for the measurement period; and evaluates a degradation state of the energy storage device, based on a relative change between a plurality of the representative data items corresponding to a plurality of the measurement periods.

Abstract: Aspects of the present disclosure include arrays of motion sensors that may be used to monitor a space to determine occupancy characteristics of the space, such as whether or not the space is occupied and the number of people located within the space. The array of motion sensors may be operatively connected to one or more building system components, such as lighting and HVAC equipment and can be used for adjusting an operating condition of the building system component based on whether a space is occupied.

Abstract: A system and method of predicting variations in a capacity of a battery, the system including an ADFM management device including an experimental data collector to collect at least one first piece of data about the capacity of the battery, an ADF optimizer to optimize a first calculation equation, and a virtual data generator to generate at least one second piece of data; and a server including a training unit to train an artificial intelligence model for outputting the relative capacity variation value by using the at least one first piece of data and the at least one second piece of data as training data, and a prediction unit to obtain a relative capacity variation prediction value, which is output from the artificial intelligence model when the number of charge and discharge cycles and the charge and discharge conditions of the battery are input to the artificial intelligence model.

Abstract: The control device for an electric motor according to this application provides a battery voltage detecting part for detecting a battery voltage at the time of driving a motor driven by a battery, and a minimum voltage holding part for keeping the battery voltage above the predetermined voltage by reducing the consumption current of the electric motor when the battery voltage detected by the battery voltage detecting part falls below a predetermined voltage during driving of the electric motor, so that it is possible to suppress a reduction in battery voltage during driving at low cost, and it is possible to keep the battery voltage above the predetermined voltage.

Abstract: An electrical energy storage system includes a battery configured to store and discharge electric power to an energy grid, a power inverter configured to use battery power setpoints to control an amount of the electric power stored or discharged from the battery, the battery power setpoints comprising at least one of frequency regulation power setpoints and ramp rate control power setpoints, and a controller. The controller is configured to use a battery life model to generate the battery power setpoints for the power inverter. The battery life model includes one or more variables that depend on the battery power setpoints.

Abstract: A physics-based calendar life model for determining the state of health of a lithium ion battery cell. The model accounts for parasitic reactions on anode and cathode particles to accurately determine degradation of a battery. By incorporating electrolyte decomposition in a cathode, the present calendar model can predict capacity retention as well as the substantial rise of cell resistance at high state of charge (SOC) and temperatures. The present calendar model is a simple algorithm, utilizing only three parameters, and determines the capacity retention and resistance rise based on temperature, SOC and time.

Abstract: A method may determine a remaining capacity of a cell that includes a lithium-alloying material in an electrode using a controller. The method includes receiving a temperature signal representing a temperature of a partially discharged cell and receiving a voltage signal representing a voltage of the partially discharged cell. The method further includes determining a time-dependent fade component and a cycle-dependent fade component of the cell. The time-dependent fade component of the cell is determined based on the temperature, the voltage, and an operating time of the cell. The cycle-dependent fade component of the cell is determined based on a depth of discharge of the partially discharged cell and cycle count data representing cycle-dependent fade from previous cycles of the cell. The method further includes determining a remaining capacity of the cell based on the time-dependent fade component, the cycle-dependent fade component, and a reference capacity of the cell.

Abstract: Apparatus, device, methods and system relating to a vehicular telemetry environment for monitoring vehicle components and providing indications towards the condition of the vehicle components and providing optimal indications towards replacement or maintenance of vehicle components before vehicle component failure.

Abstract: The present invention relates to a method for determining the state of an electrochemical reactor (1), having the steps of: operating an electrode section (2) of the electrochemical reactor (1) for the purpose of generating a harmonic current and voltage signal by means of the electrode section (2), and estimating the amplitude and/or phase of the harmonic current and voltage signal in a model-based manner, wherein the state of the electrochemical reactor (1) is determined on the basis of the estimation, wherein a recursive, time-series-based method is used to estimate the amplitude and/or phase of the harmonic current and voltage signal. The invention also relates to a diagnostic system (3), to a computer program product (5) and to a storage means (6).

Abstract: Various embodiments of the present technology may provide methods and apparatus for computing parasitic resistance in a battery system. The apparatus may provide various circuits to perform functions such as storing known battery characteristic data, measuring battery voltage, computing remaining capacity, determining whether the battery is charging in a constant current state, measuring the duration of the constant current state, and calculating the parasitic resistance based on the measured duration and the battery characteristic data.

Abstract: Provided is a method and a battery management system for estimating the parameters of an equivalent circuit model. The equivalent circuit model includes a first resistor, a second resistor connected in series to the first resistor and a capacitor connected in parallel to the second resistor. The method according to an embodiment of the present disclosure individually estimates the resistance of the first resistor and the resistance of the second resistor based on a first number of terminal voltages and a first number of currents measured in a sequential order at each time step in a sliding time window having a predefined size, and stores data indicating the estimated results in the memory.

Abstract: A method with battery state estimation may include: generating a plurality of electrochemical-thermal (ECT) models corresponding to modeling conditions based on an arbitrary parameter of an ECT model configured to perform modeling of a battery; determining a target parameter of the ECT model based on an error between an actual state of the battery and a model-derived state of the battery obtained by a parallel operation of the plurality of ECT models; and estimating a state of the battery based on the target parameter.

Abstract: Performance and lifespan of batteries deteriorate with time due to various factors. Existing systems for battery management use different approaches for the battery management, and also rely on static value of parameters for State of Health (SOH) and Remaining Useful Life (RUL) estimation, thereby failing to consider current condition of the battery. The disclosure herein generally relates to battery management, and, more particularly, to a method and system for online battery management involving real-time estimation of State of Health (SOH) and Remaining Useful Life (RUL) of a battery, based on real-time data collected from the battery. The system determines state of the battery as one of charging, discharging, and rest. Further, corresponding to the determined state, the system determines values of one or more parameters, and processes the determined values with a battery performance model for online determination of the SOH and RUL.

Abstract: Method for monitoring a stable convergence behaviour of a Kalman filter (KF), which estimates states and/or parameters of an energy storage system, in particular a battery cell (BZ), wherein a covariance behaviour—provided by the Kalman filter (KF)—in terms of at least one state and/or parameter of the energy storage system is compared with a corresponding desired covariance behaviour of the state and/or parameter, wherein the Kalman filter (KF) is automatically deactivated for each state and/or each parameter of the energy storage system, of which the covariance behaviour exceeds the corresponding desired covariance behaviour.

Abstract: A method for estimating a capacity of an electrical energy storage device with higher accuracy than what is provided in the prior art. The uncertainties in measured electrical current or voltage used in the estimation of the capacity of the electrical energy storage device are at least partly compensated for by using a bias compensated capacity estimator instead of the often-used prior art capacity estimator. The accuracy of the voltage and/or electric current sensor becomes of less importance which leads to that less complicated and less costly sensors may be used and to improve accuracy of the estimated energy storage capacity. The above advantages are obtained by providing a bias compensated capacity estimator that includes at least one bias term which is related to a deviation of an expected value of an original capacity estimator from a true capacity value.