Samlex America SAM-3000-12 - Manual (Page 13)

10 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 11
Figure 4.4 above shows a series – parallel connection consisting of four 6V, 200 Ah batteries
to form a 12V, 400 Ah battery bank. Two 6V, 200 Ah batteries, Batteries 1 and 2 are con-
nected in series to form a 12V, 200 Ah battery (String 1). Similarly, two 6V, 200 Ah batteries,
Batteries 3 and 4 are connected in series to form a 12V, 200 Ah battery (String 2). These two
12V, 200 Ah Strings 1 and 2 are connected in parallel to form a 12V, 400 Ah bank.
!
caution!
When 2 or more batteries / battery strings are connected in parallel and are then connected
to an Inverter Charger (See Figs. 4.3 and 4.4 given above), attention should be paid to the
manner in which the Inverter Charger is connected to the battery bank. Please ensure that
if the Positive output cable of the Inverter Charger (Cable “A”) is connected to the Positive
battery post of the first battery (Battery 1 in Fig. 4.3) or to the Positive battery post of the
first battery string (Battery 1 of String 1 in Fig. 4.4), then the Negative output cable of the
Inverter Charger (Cable “B”) should be connected to the Negative battery post of the last
battery (Battery 4 as in Fig. 4.3) or to the Negative Post of the last battery string (Battery 4 of
Battery String 2 as in Fig. 4.4). 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 Inverter Charger (Cable “A”) is connected to the Positive
battery post of the first battery (Battery 1 in Fig. 4.3) or to the Positive battery post of the
first battery string (Battery 1 of String 1 in Fig. 4.4), and the Negative output cable of the
Inverter Charger (Cable “B”) is connected to the Negative battery post of the first battery
(Battery 1 as in Fig. 4.3) or to the Negative Post of the first battery string (Battery 1 of Battery
String 1 as in Fig. 4.4), 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 inverter Battery Bank
The following basic rules are used to determine the size of the battery bank:
• Active Power in Watts (W) =
Voltage in Volts (V) x Current in Amperes (A) x Power Factor ...................... formula 1
• For an inverter running from a 12V battery system,
the DC current required from the 12V batteries is the
AC power delivered by the inverter to the load in Watts (W)
divided by 10 ..................................................................................................... formula 2
• Energy required from the battery =
DC current to be delivered (A) x time in Hours (H) ........................................ formula 3
• As a Rule of Thumb, Ah capacity of the batteries required =
2 x Energy required from the battery ............................................................. formula 4
SECTION 4 | Installation
11002-SAM-1000-1500-2000-3000-12-0814.indd 13 14-08-12 9:59 AM