Samlex Solar SCC-30AB Owner's Manual page 18

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GENERAL INFORMATION: BATTERIEs
Caution!
When 2 or more batteries / battery strings are connected in parallel and are then
connected to a charger (See Fig. 3.3 and 3.4), 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. 3.3) or to the Positive
battery post of the first battery string (Battery 1 of String 1 in Fig. 3.4), 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. 3.3) or to the
Negative Post of the last battery string (Battery 4 of Battery String 2 as in Fig.
3.4). 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. 3.3) or to the Positive
battery post of the first battery string (Battery 1 of String 1 in Fig. 3.4), 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. 3.3) or to
the Negative Post of the first battery string (Battery 1 of Battery String 1 as in
Fig. 3.4), 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.
Sizing the Battery Bank
The capacity of the battery bank in Ampere Hours (Ah) is determined based on the
amount of energy that is required to be provided for operating the desired DC and AC
loads for desired span of time in hours.
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