PRINCIPLES OF OPERATION
A three-step lead acid battery charger operates in the three stages described below:
1) A discharged battery is recharged at a constant current (bulk charge) until its volt-
age reaches an overcharge level of 2.45 volts per cell. At this time the charger will
switch to Finish Charge. The battery accepts 75-85% of its capacity during bulk
charge.
2) This overcharge voltage is now maintained constant at 2.45 volts per cell (absorp-
tion or finish charge) for eight (8) hours.
3) After an eight (8) hour Finish Charge Stage has completed the charger will "Time
Out" to a Float Charge Stage wherein the battery under charge will receive a
13.6VDC Float Charge or 2.26VDC per cell The battery is maintained at full charge
during Float Charge, and the green indicator labeled “Battery Charged” AND red
indicator labeled Time Out will be illuminated.
Figure 1 depicts the above described operation. Note that the term “absorption charge”
is used interchangeably with “finish charge”. Upon application of AC power, the charger
is placed into bulk charge if necessary. When the charger switches to finish charge, a
timer starts. This timer has a duration of eight (8) hours after which the charger will
automatically go to float charge (Battery Charged green indicator) and a timeout will be
indicated.
A battery fault indicator is provided to indicate the absence of a battery, a battery con-
nected with reverse polarity, or a battery with an open circuit terminal voltage of less
than 1.35 volts per cell.
TEMPERATURE COMPENSATION
Temperature compensation is provided as an optional feature. A temperature probe is
provided which can be placed in the air surrounding the battery or bonded to the battery
case.
