Automotive battery management has to work in real time in rapidly changing charging and discharging conditions
The functions of a BMS suitable for a hybrid electric vehicle are as follows:
however not all applications will require all the functions shown here.
Monitoring the conditions of individual cells which make up the battery
Maintaining all the cells within their operating limits
Protecting the cells from out of tolerance conditions
Providing a "Fail Safe" mechanism in case of uncontrolled conditions, loss of communications or abuse
Isolating the battery in cases of emergency
Compensating for any imbalances in cell parameters within the battery chain
Setting the battery operating point to allow regenerative braking charges to be absorbed without overcharging the battery.
Providing information on the State of Charge (SOC) of the battery.
Providing information on the State of Health (SOH) of the battery. This measurement gives an indication of the condition of a used battery relative to a new battery.
Providing information for driver displays and alarms
Predicting the range possible with the remaining charge in the battery (Only EVs require this)
Accepting and implementing control instructions from related vehicle systems
Providing the optimum charging algorithm for charging the cells
Providing pre-charging to allow load impedance testing before switch on and two stage charging to limit inrush currents
Providing means of access for charging individual cells
Responding to changes in the vehicle operating mode
Recording battery usage and abuse. (The frequency, magnitude and duration of out of tolerance conditions) Known as the Log Book function
Emergency "Limp Home Mode" in case of cell failure.
In practical systems the BMS can thus incorporate more vehicle functions than simply managing the battery. It can determine the vehicle's desired operating mode, whether it is accelerating, braking, idling or stopped, and implement the associated electrical power management actions.
（above information original from https://www.mpoweruk.com/bms.htm）
BMS Application example for TOPPOWER DC/DC converters: