Samlex Power PST-600-12 Manuel Du Propriétaire page 24

Section 7 |
- 85% State of Discharge (15% State of Charge) at very high C-rate discharge
current of C/3 Amps.
- 100% State of Discharge (0 % State of Charge) at high C-Rate discharge
current of C/5 Amps.
- 100% discharged (0% State of charge) at lower C-rate Discharge current of C/10 Amps.
It is seen that at DC input voltage of 10V / 20V, the battery is completely discharged for
C-rate discharge current of C/5 and lower.
In view of the above, it may be seen that a fi xed Low DC Input Voltage Alarm is not useful.
Temperature of the battery further complicates the situation. All the above analysis is based
on battery electrolyte temperature of 80°F. The battery capacity varies with temperature.
Battery capacity is also a function of age and charging history. Older batteries have lower
capacity because of shedding of active materials, sulfation, corrosion, increasing number of
charge / discharge cycles etc. Hence, the State of Discharge of a battery under load cannot
be estimated accurately. However, the low DC input voltage alarm and shut-down functions
are designed to protect the inverter from excessive current drawn at the lower voltage.
7.13 USE OF EXTERNAL PROGRAMMABLE LOW VOLTAGE DISCONNECTS
The above ambiguity can be removed by using an external, programmable Low Voltage
Disconnect where more exact voltage threshold can be set to disconnect the battery
based on the actual application requirements. Please consider using the following
Programmable Low Battery Cut-off / "Battery Guard" Models manufactured by Samlex
America, Inc. www.samlexamerica.com
- BG-40 (40A) – For up to 400W, 12V inverter or 800W, 24V inverter
- BG-60 (60A) - For up to 600W, 12V inverter or 1200W, 24V inverter
- BG-200 (200A) - For up to 2000W, 12V inverter or 4000W, 24V inverter
7.14 DEPTH OF DISCHARGE OF BATTERY AND BATTERY LIFE
The more deeply a battery is discharged on each cycle, the shorter the battery life. Using
more batteries than the minimum required will result in longer life for the battery bank.
A typical cycle life chart is given in the Table 7.6:
TABLE 7.6: TYPICAL CYCLE LIFE CHART
Depth of Discharge
% of Ah Capacity
10
50
80
100
NOTE: It is recommended that the depth of discharge should be limited to 50%.
24 | SAMLEX AMERICA INC.
General information on Lead Acid
Batteries
Cycle Life of Group
27 /31
1000
320
200
150
Cycle Life of Group
8D
1500
480
300
225
Cycle Life of Group
GC2
3800
1100
675
550