Pack design
BMS (battery management system)
The electronics that monitor cell voltages, current and temperature and disconnect the pack when any of them leave the manufacturer window.
What it changes in practice
A BMS is not optional for unprotected industrial cells. It enforces the charge voltage limit, the discharge cut-off, the current limits and the temperature window, and it decides when to stop charging because one cell group is out of balance with the rest. The important specification is not the feature list but whether the thresholds match the cell actually fitted: a BMS configured for a different chemistry or voltage window will either cut early or fail to protect.
Why it matters when you specify a cell
Separate protection from management when specifying. Over/under-voltage, over-current, short circuit and temperature cut-off are mandatory; balancing is effectively mandatory in series packs; communication and state-of-charge estimation are optional. A BMS with the right architecture and the wrong thresholds protects nothing — set them for your cell, not for the board default.
Related terms
Read further
More in Pack design
Other terms in this group
From single cell to assembled pack.
Cell balancing
Equalising the state of charge of cells connected in series, either by dissipating excess charge from the highest cells or by moving charge between them.
Read the entry →Series and parallel configuration
How cells are connected to reach the required voltage (series, written S) and capacity or current capability (parallel, written P).
Read the entry →Interconnect welding
Joining cells to busbars by resistance welding or laser welding rather than soldering, which is the accepted method for cylindrical cell assembly.
Read the entry →