A method of obtaining information relating to the charge capacity of one or more
cells utilizing information from the initial discharge period of the cell or cells.
The method involves measuring a variable cell parameter for at least a part of
an initial period of discharge during which the cell voltage initially decreases
to a through voltage and then increases to a plateau voltage (the Coup De Fouet
period), and relating the variable cell parameter to reference information to obtain
the absolute or relative charge capacity of the cell or cells. An estimation model
for predicting the absolute or relative capacity of a battery includes input for
a variable battery parameter and one or more battery operating conditions and/or
battery condition, reference information, compensation means determining a correction
factor for the variable battery parameter, and calculation means relating corrected
variable battery parameter to absolute or relative battery capacity.
