Saft SBL, Technical Manual, Page: 20 / 30

8.1
Charging generalities
The block battery can be charged
by all normal methods. Generally,
batteries in parallel operation with
charger and load are charged
with constant voltage. In operations
where the battery is charged
separately from the load, charging
with constant current or declining
current is possible. High-rate charging
or overcharging will not damage the
battery, but excessive charging will
increase water consumption to some
degree.
8.2
Constant voltage charging
methods
Batteries in stationary applications
are normally charged by a constant
voltage float system and this can be
of two types: the two-rate type, where
there is an initial constant voltage
charge followed by a lower voltage
floating voltage; or a single rate
floating voltage.
The single voltage charger is
necessarily a compromise between
a voltage high enough to give an
acceptable charge time and low
enough to give a low water usage.
However it does give a simpler
charging system and accepts a
smaller voltage window than the
two-rate charger.
The two-rate charger has an initial
high voltage stage to charge the
battery followed by a lower voltage
maintenance charge. This allows the
battery to be charged quickly, and
yet, have a low water consumption
due to the low voltage maintenance
level.
The values used for the block battery
ranges for single and two-rate charge
systems are as shown in Table 5
below.
To minimize the water usage, it is
important to use a low charge voltage,
and so the minimum voltage for the
single level and the two level charge
voltage is the normally recommended
value. This also helps within a voltage
window to obtain the lowest, and most
effective, end of discharge voltage (see
Battery sizing chapter 7).
The values given as maximum are
those which are acceptable to the
battery, but would not normally be
used in practice, particularly for
the single level, because of high
water usage.
19
8.
Battery charging
single level (V) two level (V)
min max min max floating
SBH 1.43 1.50 1.45 1.70 1.40
SBM 1.43 1.50 1.45 1.70 1.40
SBL 1.43 1.50 1.47 1.70 1.42
Table 5 - Charge and float voltages for the block battery ranges
BlockBat 3/11/98 10:12 Page 24
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