frodus wrote:well, there's several flavors of BMS, what is there definition of BMS?
A Battery Management System is defined as an electronic device connected at the series
connections of a group of battery cells with the purpose of providing automatic control
during charging and discharging to ensure that the cells charge voltage is kept within the
limits specified by the cell manufacturer.
A Battery Management System is compulsory for all entries where the battery pack cells
could present a risk of overheating leading to degradation of insulation, or ignition of
flammable material. The Battery Management System must provide a feedback loop to
the charging system to disable charging in the event that a cell or group of parallel
connected cells exceeds the charge voltage limit specified by the cell manufacturer.
Additionally, the motor controller must interrupt power supplied to the motor (s) if the
overall pack voltage is greater or less than the cell manufacturers charge voltage limits,
calculated by dividing the overall pack voltage by the number of series connected cells.
Battery Management System Recommendations
It is recommended, although not compulsory, for the Battery Management System (BMS)
to provide a cell balancing function. Cell balancing is an automatic function of a BMS unit
to control the charging process, with the purpose of ensuring that all cells connected in
series achieve an identical State of Charge (SOC). Normally, the BMS will accomplish this
by identifying the cells at the highest SOC and then reducing the SOC via a small load,
thereby allowing the charging process to continue until all cells have an equal SOC. This
process improves the performance of the pack, life cycle of cells and safety during
Temperature monitoring of cell modules via BMS or other supervisory control system is
recommended to provide safety interlocking to motor controllers, charging systems, and
issue audible and visual warnings of cells in danger of operating outside the
manufacturer’s thermal limits.