Li-ion battery diagnosis for residential use

The rapid growth of residential energy storage is outpacing expectations and these household systems are likely to become important assets in the near future. The market growth and value of these systems for customers will be an enabler of the energy transition by allowing higher flexibility and sustainability. A large deployment of residential battery storage systems (BSS) will involve additional requirements in terms of safety and consequently in predictive maintenance and fault diagnostic.

A real-time diagnostic tool running during operation of the BSS is a key element in detecting incorrect operating conditions and/or unusual behaviour of the battery that could lead to unsafe operation or accelerated ageing. Such a tool has to rely on a large measurement dataset of faulted and/or aged cells in order to compare their voltage, current and temperature gradient time evolution with healthy cells. The protection associated with over-temperature, over/under-voltage and over-current is already guaranteed by the existing battery management system (BMS).

However, even if voltage, temperature and current are within the nominal ranges declared by the battery manufacturer, their gradients and evolution over time may be an important signal of fault or incorrect operating conditions (e.g. a faulted cell may have a redistribution phenomenon involving a higher self-discharge process with a voltage that belongs to the nominal value).