Power-Sonic Sealed Lead Acid Batteries - Technical Manual - Manual (Page 10)

Performance Data
Discharge
During discharge the voltage will decrease. The graphs in Figure 4 illustrate this for different discharge rates and
ambient temperatures. “C” is the rated capacity of a battery: “C” for model PS-61O (6V – 1.1 AH) is 1.1AH. By
convention the rating of nearly all sealed-lead acid batteries, is based on a 20-hour (0.05C) discharge rate. For larger
batteries used for telecom and large UPS systems (our PG-Series) the convention is to use a 10-hour rate (0.1C).
An important feature of Power-Sonic batteries is shown in the discharge curves; namely, the voltage tends to remain
high and almost constant for a relatively long period before declining to an end voltage.
Open-Circuit Voltage
Open circuit voltage varies according to ambient temperature and the remaining capacity of the battery. Generally, open
circuit voltage is determined by the specific gravity of the electrolyte. Discharging a battery lowers the specific gravity.
The open circuit voltage of a Power-Sonic battery is 2.16 V/cell when fully charged and 1.94 V/cell when completely
discharged.
As seen in Figure 4, under load, the battery can deliver useful energy at less than 1.94 V/cell, but after the load is
removed the open circuit voltage will “bounce back” to voltages shown in Figure 5, dependent upon residual capacity.
Figure : Discharge Characteristic Curves at 0°C (°F)
Figure : Open-Circuit Voltage Characteristics
Discharge Time
Terminal V
olt
age
Terminal V
olt
age
Residual Capacity (%)