Power-Sonic Sealed Lead Acid Batteries - Technical Manual - Manual (Page 14)

Performance Data
Over Discharge
To optimize battery life, it is recommended that the battery be disconnected from the load (either electronically or
manually) when the end voltage - a function of the discharge rate - is reached. It is the voltage point at which 100% of
the usable capacity of the battery has been consumed or continuation of the discharge is useless because of the voltage
dropping below useful levels. The final discharge voltages per cell are shown in Table 1 (Page 4).
Discharging a sealed lead-acid battery below this voltage or leaving a battery connected to a load will impair the battery’s
ability to accept a charge. To prevent potential over discharge problems, voltage cut off circuits as shown in Figure 12
may be used.
Figure : Circuits of Over-Discharge Preventative Device
Charging
Dependable performance and long service life
depend upon correct charging. Faulty procedures or
inadequate charging equipment result in decreased
battery life and/or unsatisfactory performance. The
selection of suitable charging circuits and methods
is as important as choosing the right battery for the
application.
Power-Sonic batteries may be charged by using any of
the conventional charging techniques:
• Constant Voltage
• Constant Current
• Taper-Current
• Two Step Constant Voltage
To obtain maximum service life and capacity, along
with acceptable recharge time and economy, constant
voltage-current limited charging is recommended.
To charge a Power-Sonic SLA battery, a DC voltage
between 2.30 volts per cell (float) and 2.45 volts per
cell (fast) is applied to the terminals of the battery.
Depending on the state of charge, the cell may
temporarily be lower after discharge than the applied
voltage. After some time, however, it should level off.
During charge, the lead sulfate of the positive plate
becomes lead dioxide. As the battery reaches full
charge, the positive plate begins generating dioxide
causing a sudden rise in voltage due to decreasing
internal resistance. A constant voltage charge,
therefore, allows detection of this voltage increase and
thus control of the current charge amount.
Additional information regarding charging methods can
be found on pages 13 through 19.