Calculation of Battery Size
Number of Cells and Cell Voltage - the number of cells is estimated based on the maximum battery voltage and
float charge voltage:
The minimum battery voltage is the minimum system voltage (including voltage drops across cables). Given the
minimum cell voltage the minimum cell voltage is given by:
Temperature Correction - at temperature decreases the capacity of a cell decreases (and vise verse as the
temperature increases). Manufacturers quote cell capacity at a given temperature and appropriate correction factors
should be used for other temperatures.
Aging Factor - battery performance is relatively stable through out its life, dropping of rapidly towards the end. To
ensure the battery can meet the design requirements throughout its life the standard suggestions the initial capacity
should be 125% of the design capacity.
Design Margin - to cater for unexpected circumstances (increased loads, poor maintenance, recent discharge, etc.)
it is common to allow a design margin of 10% to 15%.