White Paper - Notation for Series / parallel arrangement of battery cells

Interactive utility to explore and get notation for any arrangement

This interactive utility allows you to arrange cells in a battery, displays the standard notation for that arrangement, demontrsates how the specifications are affected by the arrangement, lists pros and cons, and shows graphically what that arrangement looks like.

In a battery with cells both in series and in parallel, connecting the cells first in series or first in parallel does matter: it affects performance (in case of weak cells) and cost (BMS complexity).

The order of 'S' and 'P' in the notation for the arrangement does matter: it indicates whether cells are first connected in series or in parallel. 3P4S means that 3 cells are connected directly in parallel first; while 4S3P means that 3 strings are connected in parallel last.

Arrangement Series Parallel Single cell Series string Parallel block Series first (#S#P) Parallel first (#P#S) 2 7 12 3 8 13 4 9 14 5 10 15 6 11 16 2 7 3 8 4 9 5 10 6 11 Description Notation Note that the '' comes first. Cell specifications Cell voltage 2.4 V (LTO) 3.2 V (LFP) 3.6 V (LCO) 3.7 V (NMC) Cell capacity Ah Cell Short Discharge Time 30 s (Very hi pwr) 100 s (Power cell) 300 s (Energy cell) 1000 s (Crap cell) Battery characteristics Item Equation Value Units Total voltage V-cell x N-series V Total capacity Cap-cell x N-par Ah Total energy E-cell x N-cells Wh Short Discharge Time SDT-cell s Total DC resistance R-cell x N-ses / N-par mΩ Total max cont. current I-cell x N-par A Total max cont. power P-cell x N-cells W BMS taps required - Pros Cons

B+ B-

Standard notation of Series / parallel arrangement of battery cells.

Davide Andrea, Elithion, 4/21/17