Electrical energy storage system module level diagnostics

A method of monitoring and diagnosing, via a battery controller network, degradation of a multi-cell rechargeable energy storage system (RESS) having a plurality of battery cell groups arranged in individual battery modules, the method comprising:

• detecting voltage across each of the plurality of cell groups via a respective one of a plurality of voltage sensors, wherein the plurality of voltage sensors is mounted to or positioned on each of a plurality of cell monitoring units (CMUs) in the battery controller network, and wherein each respective CMU is electrically connected to a respective one of the battery modules and configured to process cell data for the respective battery cell groups;
• and
• executing a microchip algorithm inventory mode, via each of a plurality of microchips arranged on a respective one of the CMUs, in communication with the respective voltage sensors, and programmed with a microchip algorithm having the inventory mode, including:
• interrogating the respective voltage sensors and retrieving data indicative of the detected voltage for the associated cell groups at predetermined time intervals over a predetermined timeframe;
• storing the retrieved voltage data on the respective microchip;
• determining a discharge rate of each associated cell group using the stored data;
• and
• determining degradation of each associated cell group using the determined respective discharge rate.