Service manual
8
3.0 Maintenance
The PW 400/PW 500 weigher is designed to give many years of trouble-free service. However, in cases
where a large number of portable weighers are in constant use and facilities are available, it may be desired to
perform in-house maintenance rather than returning units to the factory. By carefully following instructions,
normal maintenance and repairs can be easily accomplished.
3.1 Recharging the Battery
Do not connect battery charger if weigher is powered by non-rechargeable
batteries!
Regular charging of the weigher’s internal battery is necessary to ensure successful day to day operation and
long battery life.
The length of time allowed to recharge the battery is just as important as how often the battery is recharged.
When fully charged, the battery operates the weigher for approximately 8 to 10 hours. This varies depending
on the temperature of the environment in which the weigher is used and stored, charging patterns and the age
of the battery. The weigher displays the following error messages to alert the operator about the battery
condition:
LOW BATTERY
This message appears approximately once every 8 seconds to alert the operator that the battery is becom-
ing low. Accurate weight readings will still be displayed in between “LOW BATTERY” indications. The
battery should be charged at the first opportunity.
RECHARGE BATTERY
This message is displayed continuously to alert the operator that the battery voltage is too low to allow
accurate weight indication to be displayed. The weigher battery must be charged at this time.
When in total mode, warning messages will be displayed for all remote scales. These messages are “REM
LOW BATTERY” and “REM RECHARGE”, indicating that a remote scale’s battery is low or needs to be
recharged. Switch to Local mode to tell which weigher has the low battery.
The weigher battery should be charged a minimum of 12 hours if it has been discharged to the point that the
“LOW BATTERY” message is displayed. Charging periods of less than 4 hours are usually ineffective
regardless of the depth of discharge.
Battery charge dissipates rapidly during extreme heat conditions even when the weigher is not in use. If the
weigher is to be stored and charged from a transport vehicle, frequent charging may be required. At least four
hours are needed for the battery to sustain any real degree of charge. Charging the battery only when the
transport vehicle is being operated provides little real degree of charge and can shorten battery life. An
overnight charge is preferred as temperatures are usually cooler at night.
NOTE: Prolonged recharging from a transport battery (in excess of 24 hours) may discharge
the transport vehicle battery.
The charger is equipped with one red and six green LED indicators mounted on the top side of the charging
unit. The red LED indicates that power to the charging unit is on. The green LEDs indicate that the weigher
battery is accepting a charge. When connecting the weighers to the charging unit, look to see that the corre-
sponding green light is on to verify that the weigher battery is drawing current from the charger. The green
light will go out when the weigher battery is drawing 50 mA or less current from the charger, indicating that
the battery is fully charged.
An optional 110/120 VAC charging station is also available for use in calibration labs and maintenance areas.
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Caution