Samlex Solar SCC-30AB Mode D'emploi page 25

Figure 3.4 above shows a series – parallel connection consisting of four 6V, 200 AH
batteries to form a 12 V, 400 AH battery bank. Two 6 V, 200 AH batteries, Batteries 1
and 2 are connected in series to form a 12 V, 200 AH battery (String 1). Similarly, two
6 V, 200 AH batteries, Batteries 3 and 4 are connected in series to form a 12 V, 200 AH
battery (String 2). These two 12 V, 200 AH Strings 1 and 2 are connected in parallel to
form a 12 V, 400 AH bank.
Caution!
When 2 or more batteries / battery strings are connected in parallel and are then
connected to a charger (See Figs. 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.
GENERAL INFORMATION: BATTERIEs
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