Kussmaul Electronics 091-127-12E-80 - Manual (Page 3)

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 voltage
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 (absorption
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 time-out will be indicated.
A battery fault indicator is provided to indicate the absence of a battery, a battery connected
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.