Battery knowledge · Modules, packs and battery management

String

A chain of cells or modules connected in series to reach the system voltage, the basic electrical unit of a large battery. In stationary storage each rack is usually one string of about 1000–1500 V with its own contactors and BMS, and many strings are paralleled on a common DC bus.

Also called
battery string, series string

Example

Series voltage and parallel capacity

4S2P: 8 cells, 14.8 V, 10 Ah, 148 Wh.

Identical 3.7 V, 5 Ah cells; ideal equal current sharing and no losses.

Explore the graph

Count series and parallel connections separately.

Voltage along one series string
Voltage along one series stringSeries cells versus Voltage (V). 3.7 V per cell. Interpretation follows the graphs.0011.1322.2633.3944.412Series cellsVoltage (V)
3.7 V per cell
Capacity from parallel cells
Capacity from parallel cellsParallel cells versus Capacity (Ah). 5 Ah per cell. Interpretation follows the graphs.007.51.515322.54.5306Parallel cellsCapacity (Ah)
5 Ah per cell

4S2P: 8 cells, 14.8 V, 10 Ah, 148 Wh.

V_pack = Ns V_cell; Q_pack = Np Q_cell

Illustrative model. Identical 3.7 V, 5 Ah cells; ideal equal current sharing and no losses.

Use in Lemonergy

Make series/parallel architecture explicit.

This is a reference concept. No executable Lemonergy block has been verified for this term.

References & further reading

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

  1. Extended Kalman filtering for battery management systems of LiPB-based HEV battery packs: Part 2. Modeling and identification

    Gregory L. Plett · Journal of Power Sources · 2004

    Topic background · Battery charge balance, open-circuit voltage, ohmic loss, polarization dynamics and model identification; parameters require cell-specific data.

  2. Getting Started with the BQ76925

    Texas Instruments · 2019

    Topic background · A concrete BMS analog front-end example: cell voltage, current, temperature measurement and MCU integration.