13
Parallel
Connecting two batteries in parallel will
double the amp-hour rating of the battery bank,
while the voltage will be the same as each
individual battery. For example, two 12-volt 105
amp-hour batteries in parallel will produce one
12-volt 210 amp-hour battery bank.
BATTERIES
Parallel
Parallel
Increase Amp-Hour Capacity
EACH BATTERY
CAPACITY:
105
AMP HOURS
@ 12 VDC
TOTAL BATTERY
BANK CAPACITY:
210
AMP HOURS
@ 12 VDC
Only similar batteries should be
connected together in one bank.
Do not
connect old and new batteries together or wet
and gel cell batteries together. In the above
drawing, the load is connected to the positive
terminal of the first battery and the negative
terminal of the last battery. This practice helps
to balance the battery bank and is called
cross-connecting
the battery bank.
Note: It is not advisable to connect
batteries of different case sizes or amp-hour
ratings in the same battery bank.
Always use properly sized wire and
terminals for your interconnecting battery
cables. For size information refer to NEC
requirements or contact your local
electrician.
BATTERY BANK RATINGS AND SIZING
Deep-cycle batteries are usually rated in
amp hours. The amp-hour rating is based on a
20-hour discharge rate; therefore, a 100
amp-hour battery can deliver 5 amps for 20
hours. If the discharge rate is greater than 5
amps, the available amp hours are decreased.
For example, if the load is increased to 100
amps, only about 45 amp hours will be avail-
able at this rate of discharge.
Deep-cycle batteries can be discharged
about 80% of capacity before damage occurs.
Shallow cycling will result in much longer
battery life. Calculating a battery bank size
based on 50% discharge cycling is generally
considered to be a good compromise between
long battery life and size.
+
+
+
+
_
+
_
_
12 V INVERTER
12 V
12 V
