System Operation
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IPN 997-00012-03 B2 Issue B2 July 2018
73
Battery Time Remaining
The SC300 obtains characterization data from every full battery discharge, to a specified end
voltage.
During a battery discharge, the SC300 uses this characterization data to calculate an estimated time
until the battery will reach the specified end voltage.
If a battery disconnect LVD is fitted then the end voltage will usually be the voltage at which the
LVD disconnects the battery.
Battery Time Remaining is designed for a constant power load. The accuracy of the time remaining
calculation will be reduced if the dc power system is connected to a predominantly resistive
(constant current) load.
The time remaining calculation will not be correct if a non-essential load is disconnected during
the battery discharge.
Battery Time Remaining cannot be used for very small battery strings (<20Ah) due to limits in
current resolution.
Battery characterization and Battery Time Remaining are not recommended under these
conditions:
•
With a battery C10 capacity of less than 30Ah
•
If load current is less than twice the Battery State Threshold setting.
•
If load current is less than 10A.
Configuration
It will take at least 10 hours to characterize a battery.
When a battery is characterized it is fully discharged. The bus voltage will gradually
reduce to the battery end voltage. Ensure that this will not affect the operation of any
equipment connected to the dc power system.
Use the following procedure to configure
Battery Time Remaining
for the first time, or if a previously
characterized battery is changed.
Battery Characterization is not necessary if a previously saved battery characterization data file is
available. Refer to Characterization Data Management on page 76. Only use characterization data
for an identical type and size of battery.
► To configure Battery Time Remaining
1
Check that all battery strings are connected and all LVD contactors (if any) are connected.
During a battery characterization, LVD contactor disconnection is inhibited. If any LVD
contactor is configured to connect during a battery discharge then set it to Manual Connect to
prevent operation during the battery characterization.
2
Check that all battery strings are fully charged.
When a battery is fully charged, the Battery Charge State will be Float and Ah Discharged will be
zero. See Batteries on page 68.
3
Check that all battery parameters are set to the correct values. See Batteries Configuration on
page 69.
4
Check that the load current is at least 10% of the C10 capacity of the batteries (
Battery Capacity
)
and at least 150% of the
Battery State Threshold
. See Batteries Configuration on page 69.
If the load current is less than 10% of the C10 capacity of the batteries, then Battery
Characterization will take longer than 10 hours.
