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Appendix B: Battery Functions
Float Mode
Float mode is the default mode of operation of the battery plant. The plant voltage, while in float
mode, is determined by the configuration parameter Rectifier Float Set point (fsp) and may be
adjusted by the Battery Thermal Compensation circuit, if active. No individual adjustment of plant
rectifiers is necessary and load sharing among plant rectifiers is automatic in all plant modes and will
take effect within several seconds of a new rectifier being added to the system.
The fsp should be set per the battery manufacturer's recommendations. Note that the actual fsp
measured on the plant may differ from the value set by the user if thermal compensation is enabled.
See Slope Thermal Compensation (next topic) for more details.
Slope Thermal Compensation
The following is a list of slope thermal compensation parameters that can be configured in the
controller.
High Temperature Alarm
Alarm threshold can be set from 30°C to 85°C. The alarm retires when the temperature drops to 10°C
below the set threshold. The factory default setting is 55°C.
High Temperature Compensation
The system controller automatically enables high temperature compensation if a VT thermal probe is
detected. The feature can be disabled by disconnecting all thermal probes and updating the serial links
using the Lamp Test function. Settings for this feature are as follows.
V Step Down: Battery step temperature can be set from 45°C to 85°C. The factory default setting is 75°
C.
High Comp Limit: The upper temperature thermal limit can be set from 30°C to 55°C. The factory
default setting is 45°C.
Decrease: The upper temperature slope setting (rate of decrease) can be set from -1mV to - 10mV
in -2mV steps. The factory default is -3mV.
Nominal Temperature: Temperature above or below which Slope Thermal Compensation is enabled.
The stable range is 15 to 30°C. The factory default setting is 25°C.
Low Temperature Compensation
This feature is disabled by default, and can be enabled only if Temperature Slope Thermal
Compensation is enabled. The following are the associated parameters.
Low Comp Limit: Low temperature thermal compensation can be set from -5°C to 20°C. The factory
default setting is 0°C.
Increase: The low temperature slope (rate of increase) can be set from 1mV to 10mV in 1mV increments.
The factory default setting is 3mV.
The QS840A has a flexible Thermal Compensation feature which provides voltage compensation from
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