Abstract: A method for non-invasive characterisation of a cell for a battery is provided, the method comprising: measuring a magnetic field generated by the cell using a plurality of magnetic field sensors positioned adjacent to the cell, the measuring producing magnetic field sensor data, wherein the measuring is performed while the cell is in a passive state; determining current density profile data across the cell based on the magnetic field sensor data; and determining a condition of the cell using the current density profile data.

Abstract: A sensor arrangement for a network of busbar links of a battery module is provided, the sensor arrangement comprising: an array of sensors, each sensor having an output arranged to provide an indication of current in a respective busbar link of the network; a processor coupled to the outputs of the sensors and configured to: receive data from the sensor outputs; process the data to determine a current in each of a set of busbar links that are connected at a node of the network; and compare the currents in the busbar links of the set to determine an overall current at the node.