10
Operation
2.1.2 Operation from the Internal Battery
The 918B Phase Angle Multimeter features an internal 9.6 volt
nickel-cadmium rechargeable battery, which will permit operation
of the instrument for a minimum of 25 hours between charges.
2.1.3 Battery Test
At initial power-up the instrument will automatically perform a
battery voltage measurement. If the battery voltage is above 11
volts, the instrument will recheck the voltage once per hour. When
the measured voltage falls below 11 volts, the frequency of the
battery voltage test will increase to once every fifteen minutes.
When the battery voltage falls below approximately 9.2 volts, the
display will indicate "LoBat". At this point, the charger should be
connected.
Whenever the momentary battery test is being performed, the
display will change briefly to read, "Battery Test".
2.1.4 Charging the Internal Battery
To charge the 918B internal batteries, connect the power pack to the
ac line and the power inlet jack on the rear panel. Internal power
management circuitry will automatically evaluate the charge state of
the battery, and select one of two charging rates. A high charging
rate is applied initially, until the battery is near full capacity. After
this, a lower, "trickle" charge rate is used, allowing the 918B to be
connected to the ac line indefinitely without danger of overcharging.
When the unit is turned off during charging, the front panel display
will indicate which of the charge rates is being used, and the voltage
of the battery. This display is updated every 15 minutes.
A completely discharged battery will require approximately 6-8
hours to reach full charge. To maximize the operational life of the
battery, it is advisable to allow full discharge prior to recharging.