Samlexpower SEC-1260A Owner's Manual page 10

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CAUTION!
CAUTION
When 2 or more batteries / battery strings are connected in parallel and are then connected
to a charger (See Figs. 2 and 3 given above), attention should be paid to the manner in which
the charger is connected to the battery bank. Please ensure that if the positive output cable
of the battery charger (Cable "A") is connected to the positive battery post of the first
battery (Battery 1 in Fig. 2) or to the positive battery post of the first battery string
(Battery 1 of String 1 in Fig. 3), then the Negative output cable of the battery charger
(Cable "B") should be connected to the Negative battery post of the last battery (Battery
4 as in Fig. 2) or to the Negative Post of the last battery string (Battery 4 of Battery String
2 as in Fig. 3). This connection ensures the following:
•
The resistances of the interconnecting cables will be balanced.
•
All the individual batteries / battery strings will see the same series resistance.
•
All the individual batteries will charge at the same charging current and thus, will be
charged to the same state at the same time.
•
None of the batteries will see an overcharge condition.
If the positive output cable of the battery charger (Cable "A") is connected to the positive
battery post of the first battery (Battery 1 in Fig. 2) or to the positive battery post of the
first battery string (Battery 1 of String 1 in Fig. 3), and the Negative output cable of the
battery charger (Cable "B") is connected to the Negative battery post of the first battery
(Battery 1 as in Fig. 2) or to the Negative Post of the first battery string (Battery 1 of
Battery String 1 as in Fig. 3), the following abnormal conditions will result:
•
The resistances of the connecting cables will not be balanced.
•
The individual batteries will see different series resistances.
•
All the individual batteries will be charged at different charging current and thus, will
reach fully charged state at different times.
•
The battery with lower series resistance will take shorter time to charge as compared to
the battery which sees higher series resistance and hence, will experience over charging
and its life will be reduced.
Effect of Temperature on Battery Voltage
The chemical reactions inside the battery change with temperature. The cell voltage has a
negative temperature coefficient - the cell voltage drops with increase in temperature.
Normally, the voltages are specified at 80
as follows:
12 V battery
24 V battery
o F. The charging voltages should be compensated
- 0.030 V per degree C ( -0.017 V per degree F)
- 0.060 V per degree C ( -0.033 V per degree F)
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