Dataman S4 - Manual (Page 33)

DATAMAN S4 MANUAL
INFO KEY 33
Defective Battery
NICAD manufacturers claim that "deep cycling",
meaning full charges and discharges, is good
for the battery; apparently this discourages
physical change, the formation of dendrites,
which cause premature failure.
Electronics lore is that Nicads "learn" the
capacity that their job requires and refuse to
hold more charge. Some authorities claim this
is not true and at Dataman we have never
observed this effect. What we have seen is
that there is a low but constant rate of failure in
Nicad cells which is not dependent on age.
New ones seem to fail occasionally - as often
as old ones. They seem to do better if worked
hard, i.e. charged and discharged quickly.
The symptoms of a defective battery are that it
does not reach normal output voltage. Nicad
cells usually fail by going short. If one of the
seven Nicads cells is short, the battery will
charge to temperature cut-off but remain below
9 volts, because it only has 6 cells instead of 7.
The combination of high temperature and low
voltage can be observed in the INFO display.
The battery should be replaced as soon as
possible.