113 XFC G4 2103335 Rev AB
6.5.3 Backward clock change crossing an hourly boundary
Hourly entry is made for part of hour that has accumulated since making last hourly entry. This is same as for a Forward Clock
Change Crossing an Hourly Boundary. The flow computer advances to a new day’s data flow record and maintains balance of
day’s data in new record.
Example: If present time is 5:05 p.m. and clock is changed to 4:55 p.m. of the same day, the log period record entry reflects
only a 5 minute average accumulation. Then a new flow record is written and this log period is based on a 60 minute
accumulation.
IMPORTANT NOTE: A backward clock change uses two (2) records to maintain data integrity. This assures that
previously recorded data is not overwritten.
If it is necessary to make small backward time changes, less than one (1) hour, user should wait until current
hour has progressed far enough to make change that does not cross an hour boundary.
6.6 Replacing the lithium battery
This section presents the procedures for replacing the onboard lithium battery which maintains the SRAM memory. Replacing
the lithium battery should only be done while the flow computer is fully powered by the battery pack or charging system. SRAM
memory stores historical flow data.
To replace the lithium battery:
NOTICE – Loss of data. Do not remove power to unit. Loss of power to unit will perform a Cold Start when
lithium battery is removed. All historical data and any changes to the configuration that have not yet been saved
to TfCold will be lost.
Connect the PC running PCCU32 to the flow computer with either an MMI cable (RS-232), a USB cable or an
Ethernet cable.
Open PCCU.
Collect the Data from the unit as described in section 6.2.1, Data collection (page 108).
Back up configuration files as described in section 6.2.2, Back up configuration files (save) in page 108.6.2.2
Open the XFC enclosure door.
Remove the lithium battery cover from the battery bracket by inserting the blade of a slotted screwdriver between the
cover and the side of the bracket.
Grasp the battery on each side and pull from the bracket. The positive end of the battery is at the bottom end of the
bracket.
Insert the new lithium battery into the bracket with the positive end of the battery down.
Reinsert the battery cover.
6.7 Replacing XFCG4 Battery Pack
This section presents the procedures for removal and installation of the battery pack. To access the battery pack, open the door.
Battery pack is located behind a front mounted keeper plate. On the XFC
G4
6713/6714 models, the Battery is located directly
behind a hinged plate on which the I/O module DIN rails are mounted if applicable.
IMPORTANT NOTE: To extend the life of the battery pack, fully charge the battery prior to installation. A system
using solar panels may not fully charge the battery. Also a fast charge, which the solar panel can’t provide,
improves the life of the battery.
To recharge a battery, a quick charge will remove the buildup in the battery much more effectively than a “trickle
charge”. A battery slowly drained by low light conditions on a solar charged system or setting in storage for
instance, will be less likely to recover than a battery pack that was quickly discharged from a short for instance.
Store batteries in a cool environment for less drainage.
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