employed with sealed batteries to return full capacity
as quickly as possible.
To maintain capacity on a fully charged battery, a
constant voltage is applied. The voltage must be
high enough to compensate for self discharge, yet
not too high as to cause excessive over-charging.
While simply maintaining a fixed output voltage is a
relatively simple function, the battery’s temperature
coefficient of -3.9mV/degree C per cell adds
complication. If battery temperature is not
compensated for, loss of capacity will occur below
the nominal design temperature, and over-charging
with degradation in life will occur at elevated
temperature