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9
TYPICAL BATTERY CONNECTIONS
Solar Charge Controller
SCC30-AB (rear view)
Solar Charge Controller
SCC30-AB (rear view)
Solar Charge Controller
SCC30-AB (rear view)
PV +
PV -
BAT +
BAT -
6V Battery
6V Battery
PV +
PV -
BAT +
BAT -
12V Battery
12V Battery
12V Battery
12V Battery
PV +
PV -
BAT +
BAT -
6V Battery
6V Battery
6V Battery
6V Battery
String 1
String 2
Battery 1
Battery 3
Battery 2
Battery 4
Battery 1
Battery 3
Battery 2
Battery 1
Battery 2
Battery 4
Cable “A”
Cable “B”
Cable “A”
Cable “B”
Cable “A”
Cable “B”
CAUTION!
When 2 or more batteries / battery strings are connected in parallel and are then connected to
the Solar Charge Controller SCC30-AB (See Figs. 9.2 and 9.3. given above), attention should be
paid to the manner in which the solar charge controller is connected to the battery bank. Please
ensure that if the positive output cable of the solar charge controller (Cable “A”) is connected
to the positive battery post of the first battery (Battery 1 in Fig. 9.2.) or to the positive battery
post of the first battery string (Battery 1 of String 1 in Fig. 9.3.), then the Negative output cable
of the Solar Charge Controller SCC30-AB (Cable “B”) should be connected to the Negative battery post of the last
battery (Battery 2 as in Fig. 9.2) or to the Negative Post of the last battery string (Battery 4 of Battery String 2 as
in Fig. 9.3.). 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. 9.2.) or to the positive battery post of the first battery string (Battery 1 of String 1 in Fig.
9.3.), 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. 9.2.) or to the Negative Post of the first battery string (Battery 1 of Battery
String 1 as in Fig. 9.3.), 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.
Figure 9.3. above shows a series – parallel connection consisting of four 6 V, 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.
Fig. 9.3. Series-Parallel Connection
9.3. Series – Parallel Connection of Batteries
