Three-Stage Battery Charger; Figure 10, Three-Stage Charging Profile - Trace Engineering LEGEND II Manual

The Legend Series II inverter/charger has a fully functional three-stage battery charger. Anytime an
acceptable (within frequency and voltage parameters) AC source is presented to the unit, it will
charge the batteries connected to it. The On/Off switch on the inverter does not control the charger
portion of the unit. When AC is present the charger will charge the battery bank regardless of the
position of the inverter's On/Off switch.
AC is fed into the inverter's AC input and the transformer steps the high voltage AC down to lower
voltage AC. This power is rectified and fed to the battery bank to charge it. The charger is fully
regulated, and protection systems prevent abuse of the battery bank due to overcharge, over-temp,
and/or charger failures
The battery charger in the Trace Legend Series II inverters charges in three stages - BULK,
ABSORPTION, and FLOAT - to provide rapid and complete charge cycles without undue battery
gassing. The figure below shows how DC voltage and current change with time through the
different charge stages.
Charging
Started
DC Voltage
AC Current
Time
WK

Absorption Charge
Bulk
Bulk Volts Setting
Absorption Time
Constant Current
@ Maximum
Charge Rate
Constant Voltage

Figure 10, Three-Stage Charging Profile

90 Minute
Reduced Current and Voltage
Float Charge
Float Volts Setting