Outback Power Systems GS3548E Operators Manual - Manual (Page 31)

Operation
900-0145-01-01 Rev A 29
Charging Steps
The following items describe the operation and intended use for each individual charging step as
shown in the graphs. Note that some charging cycles may not follow this exact sequence. These
include cycles which were previously interrupted, and also customized charging. Each step describes
how to defeat or customize the step if specialized charging is required.
See page 31 for a description of multiple cycles when the charger is restarted after completion.
This page also describes multiple cycles when the charger is restarted after being interrupted.
For multiple inverters:
The charging of parallel stacked inverters is synchronized by the master inverter. The charger settings
of slave or subphase masters are ignored. Slaves or subphase masters use the master inverter settings.
No Charging
If the inverter is not charging, any of the following conditions may apply:
 The unit is not connected to a qualified AC source. If a generator is present, it may not be running.
 The unit is connected to an AC source but is in a mode or step (such as Silent) that does not use the charger.
 The unit is connected to an AC source but the charger has been turned off.
Bulk Stage
This is the first stage in the three-stage charge cycle. It is a constant-current stage which drives the
battery voltage up. This stage typically leaves the batteries at 75% to 90% of their capacity,
depending on the battery type, the exact charger setting, and other conditions.
Voltage Used: Absorb Voltage setting. The default setting is 57.6 Vdc.
The initial DC current may be as high as the charger’s maximum current, depending on conditions.
It will begin at a high level, but will drop slightly as the voltage rises. This is not a decrease in charging;
the charger delivers constant power in Bulk stage. It can be viewed as a wattage “tradeoff”; the
increase in voltage results in a decrease in current for a constant wattage.
To skip this step: Setting Absorb Voltage equal to Float Voltage will cause the charger to proceed
through the normal three-stage cycle, but at a single voltage. Setting
Absorb Time to zero will cause
the charger to skip both the Bulk and Absorption stages and proceed directly to Float. This may not
be desired if the intent is to include the Bulk stage but skip Absorption.
Absorption Stage
This is the second stage of charging. It is a constant-voltage stage. Current varies as needed to
maintain the voltage, but will typically decrease to a very low number over time. This “tops off the
tank”, leaving the batteries at essentially 100% of capacity.
Voltage Used: Absorb Voltage setting. This setting is also used by Offset when in this stage. (See
page 35.) For the three-stage cycle to proceed normally, this setting should be kept higher than the
Float Voltage and Re-Bulk Voltage settings.
Time limit: Absorb Time setting. This timer counts down from the inception of the Absorption stage
until it reaches zero. The time remaining can be viewed in the system display.
The Absorption timer does not reset to zero when AC power is disconnected or reconnected. It only
resets to zero if it runs out, or if an external STOP BULK command is sent; otherwise it retains any
remaining time.
The
Absorb Time setting is not a required minimum period for Absorption. It is only a maximum limit.
The duration of Absorption is equal to the amount of time the Re-Bulk Voltage setting exceeds the
battery voltage (up to the maximum Absorption limit). The counter adds more time to the Absorption