A controller discharges a traction battery according to power limits defined by output that is indicative of a state of charge of the traction battery and is updated by a bar delta filter according to a balancing current. The balancing current is associated with each cell of a string of series connected cells of the traction battery and represents a deviation of an estimated current through the cell from a total current of the string.

A current detection circuit includes a current sampling branch, a switch branch, a first current mirror branch, a capacitor branch, a feedback branch and a control branch. The control branch receives the second current and outputs the first current and the first voltage signal. The current sampling branch outputs a first discharging current. The switch branch establishes and disconnects the connection between the first current mirror branch and the capacitor branch. The capacitor branch is charged in response to the first charging current and discharged in response to the first discharging current. The first current mirror branch outputs the first charging current. The feedback branch adjusts the second charging current to adjust the first charging current, so that the total charge of the capacitor branch is balanced with the total charge of discharge within one switching cycle, so that the first current is represented by the first charging current.

A current detection circuit includes a current sampling branch, a switch branch, a first current mirror branch, a capacitor branch, a feedback branch and a control branch. The control branch receives the second current and outputs the first current and the first voltage signal. The current sampling branch outputs a first discharging current. The switch branch establishes and disconnects the connection between the first current mirror branch and the capacitor branch. The capacitor branch is charged in response to the first charging current and discharged in response to the first discharging current. The first current mirror branch outputs the first charging current. The feedback branch adjusts the second charging current to adjust the first charging current, so that the total charge of the capacitor branch is balanced with the total charge of discharge within one switching cycle, so that the first current is represented by the first charging current.

Methods and electronic devices for estimating state of charge (SOC) of a battery pack. Various embodiments provide a model comprising an (electrical) equivalent circuit model, an electrochemical (thermal) model, and a (convective) thermal model. The model estimates parameters pertaining to each cell of the battery pack individually, and determines the variations in the values of the parameters among each of the cells of the battery pack. The parameters include capacity, temperature current, voltage, and SOC. The parameters are computed based on at current drawn by the battery pack, electrochemical parameters, thermal parameters, and cell internal and connection resistances of the individual cells. Various embodiments compute battery pack uptime, chargeable capacity of the battery pack and SOC of the battery pack, based on the values of the parameters.

Methods and electronic devices for estimating state of charge (SOC) of a battery pack. Various embodiments provide a model comprising an (electrical) equivalent circuit model, an electrochemical (thermal) model, and a (convective) thermal model. The model estimates parameters pertaining to each cell of the battery pack individually, and determines the variations in the values of the parameters among each of the cells of the battery pack. The parameters include capacity, temperature current, voltage, and SOC. The parameters are computed based on at current drawn by the battery pack, electrochemical parameters, thermal parameters, and cell internal and connection resistances of the individual cells. Various embodiments compute battery pack uptime, chargeable capacity of the battery pack and SOC of the battery pack, based on the values of the parameters.

A method for estimating the state of health of an exchangeable rechargeable battery. The method includes: i. determining a remaining capacity of the battery during a charging operation, in such a manner, that a first charging value is ascertained by measuring an open-circuit voltage, as long as no charging current or only a minimal charging current is flowing; at least one further charging value is ascertained by measuring the charging current in specific time intervals, until the charging operation is completed; and a sum of the ascertained charging values is calculated; ii. determining a remaining performance of the battery during the charging operation in such a manner, that after a predefined battery voltage is reached, the charging current is briefly changed, and the respective battery voltage is measured; and an impedance of the battery is calculated from the quotient of the difference of the measured charging currents and battery voltages.

A battery control apparatus for a battery system includes: a first operation unit that computes a first state of charge of a battery according to a first technique on the basis of an electric current value, a voltage value, and an internal resistance value of the battery; a second operation unit that computes a second state of charge of the battery according to a second technique different from the first technique; and a correction unit that corrects the internal resistance value of the battery. if a difference equal to or more than a specified value is detected between the first state of charge and the second state of charge, the correction unit corrects the internal resistance value of the battery with a resistance correction amount according to the difference and the electric current value.

A battery control apparatus for a battery system includes: a first operation unit that computes a first state of charge of a battery according to a first technique on the basis of an electric current value, a voltage value, and an internal resistance value of the battery; a second operation unit that computes a second state of charge of the battery according to a second technique different from the first technique; and a correction unit that corrects the internal resistance value of the battery. if a difference equal to or more than a specified value is detected between the first state of charge and the second state of charge, the correction unit corrects the internal resistance value of the battery with a resistance correction amount according to the difference and the electric current value.

An example of a battery apparatus (10) is provided including: a housing (12) with a connection arrangement (24); a plurality of interoperable battery cartridges (36) removably fittable to the housing (12) to connect with the connection arrangement (24) to form a stack; at least one battery interface arrangement (17) adapted to be removably fitted to the housing (12) to connect with the connection arrangement (24) so as to be in communication with a selection of the plurality of interoperable battery cartridges (26) via the connection arrangement (24). Examples of battery cartridges (36), a system (5) including one or more battery apparatuses (10), and associated example methods are also disclosed.

In a battery apparatus, a battery pack includes a plurality of battery modules and a bus-bar connecting two battery modules among the plurality of battery modules. A wire connects the battery pack and the switch for controlling current supply of the battery pack. A voltage measuring circuit measures a voltage of the bus-bar, a voltage of the battery pack, and voltages of the plurality of battery modules. A processor diagnoses a connection status of the bus-bar and a connection status of the wire based on a current of the battery pack, the voltage of the bus-bar, the voltage of the battery pack, and the voltages of the plurality of battery modules.