SAMLEX AMERICA INC. | 29
Now, the capacity of the batteries is determined based on the run time and the usable capacity.
From Table 1.4.3 “Battery Capacity versus Rate of Discharge”, the usable capacity at 3 Hour discharge rate (C/3) is
60%. Hence, the actual capacity of the 12V batteries to deliver 300 Ah will be equal to: 300 Ah ÷ 0.6 = 500 Ah,
and the actual capacity of the 24V battery to deliver 150 Ah will be equal to 150 Ah ÷ 0.6 = 250 Ah.
And nally, the actual desired rated capacity of the batteries is determined based on the fact that normally
only 80% of the capacity will be available with respect to the rated capacity due to non availability of ideal and
optimum operating and charging conditions. So the nal requirements will be equal to:
FOR 12V BATTERY: 500 Ah ÷ 0.8 = 625 Ah (note that the actual energy required by the load was 300 Ah).
FOR 24V BATTERY: 250 Ah ÷ 0.8 = 312.5 Ah (Note that the actual energy required was 150 Ah).
It will be seen from the above that the nal rated capacity of the batteries is almost 2 times the energy required by
the load in Ah. Thus, as a Rule of Thumb, the Ah capacity of the batteries should be twice the energy required by the
load in Ah.
1.14.18 Charging Batteries
Batteries can be charged by using good quality AC powered battery charger or from alternative energy sources like
solar panels, wind or hydro systems. Make sure an appropriate Battery Charge Controller is used. It is recommended
that batteries may be charged at 10% to 20% of their Ah capacity (Ah capacity based on 20 Hr Discharge Rate).
Based on the application, batteries may be charged using 2-Stage / 3-Stage / 4-Stage Charging Proles as follows:
Float Application Charging (2-Stage)
Stage 1 (Bulk Stage at constant current) " Stage 2 (Absorption Stage at constant voltage. May also be called Float
Stage in some applications).
Normal Charging (3-Stages)
Stage 1 (Bulk Stage at constant current) " Stage 2 (Absorption Stage at constant voltage) " Stage 3 (Float Stage
at constant voltage)
Equalization Charging (4-Stages)
Stage 1 (Bulk Stage at constant current) " Stage 2 (Absorption Stage at constant voltage) " Stage 3 (Equalization
Stage at constant voltage) " Stage 4 (Float Stage at constant voltage)
Please refer to Section 5 for details of charging algorithm used in the Battery Charger Section of EVO
™
Series
Inverter/Charger.
SECTION 1.4 | General Information – Battery Related
To Next Page
Loading...
