
23
9.1
Electrical abuse
Ripple effects
The nickel-cadmium battery is tolerant
to high ripple and will accept ripple
currents of up to 0.5C
5
peak to peak.
In fact, the only effect of a high ripple
current is that of increased water
usage. Thus, in general, any
commercially available charger
or generator can be used for
commissioning or maintenance
charging of the block battery.
This contrasts with the valve regulated
lead-acid battery (VRLA) where
relatively small ripple currents can
cause battery overheating, and will
reduce life and performance.
Thus, for VRLA, the charger voltage
must fall within ± 2.5 % of the
recommended float voltage.
Over-discharge
If more than the designed capacity is
taken out of a battery then it becomes
over-discharged. This is considered
to be an abuse situation for a battery
and should be avoided.
In the case of lead acid batteries this
will lead to failure of the battery and
is unacceptable.
The block battery is designed to make
recovery from this situation possible.
Overcharge
In the case of the block battery,
with its generous electrolyte reserve,
a small degree of overcharge over
a short period will not significantly
alter the maintenance period. In the
case of excessive overcharge, water
replenishment is required, but there
will be no significant effect on the life
of the battery.
9.2
Mechanical abuse
Shock loads
The block battery concept has been
tested to both IEC 68-2-29 (bump
tests at 5 g, 10 g and 25 g) and
IEC 77 (shock test 3 g).
Vibration resistance
The block battery concept has been
tested to IEC 77 for 2 hours at 1 g.
External corrosion
The block battery is manufactured
in durable polypropylene. All external
metal components are nickel-plated or
stainless steel, protected by a neutral
grease, and then protected by a rigid
plastic cover.
9.
Special operating factors
BlockBat 3/11/98 10:12 Page 28
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