Balance in batteries

A problem that appears immediately when a specific single-cell battery is designed is the required ratio of the reactants for the positive and negative electrodes and for the electrolyte. An unnecessary excess in one of the components is undesirable. It is therefore typical for the reactants to be loaded in the stoichiometric ratio given by the current-producing reaction with the actual utilization coefficient of each of 

Electrochemical Power Sources Batteries, Fuel Cells, and Supercapacitors, First Edition. Vladimir S. Bagotsky, Alexander M. Skundin, and Yurij M. Volfkovich 2015 John Wiley Sons, Inc. Published 2015 by John Wiley Sons, Inc. 

Another problem is that of balance between single cells in a multicell battery. Such batteries are balanced when all cells (preferably of the same type) have the same capacity and the same state of charge (SOC). In case of a mismatch between cells connected in series the battery s ampere-hour capacity is determined by the cell with the least available ampere-hour capacity. In case of cells connected in parallel, a failure (e.g., short circuit) of one of the cells can lead to the failure of the whole battery. 

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