Quoting the NTSB report
http://www.ntsb.gov/investigations/2...787_3-7-13.pdfBMU1 monitors for cell overcharge, overdischarge, overheating, and imbalance; controls the cell balancing function when any cell reaches a predetermined threshold; and is the source of voltage for the BCU. BMU2 provides a redundant monitor for cell overcharge. BMU3 controls the contactor and provides additional monitoring for battery and cell overcharge. BMU4 monitors for cell overdischarge and high current charge. If any of the battery monitoring thresholds were exceeded, the BMU was designed to send a signal to the BCU to discontinue charging. The BMU main circuit card and sub-circuit card do not contain nonvolatile memory (NVM), and none of the BMU data are recorded on the FDR.
So if it is not stored in NVM, nor recorded in the FDR, where does the data about cell overdischarge goes?