Keysight N9912A Service Manual page 59

Theory of Operation
Grounding and Power
Battery Charging Management
The battery pack determines when the battery needs charging and requests a
charge over the Smart Batt Bus.
The Battery Charger and Manager circuit on the A5 system board responds by
charging the battery if there is sufficient voltage on the Ext DC line. A minimum
of approximately 15 volts is required to charge the battery.
The System Monitor on the A5 system board monitors the battery's
temperature and, if too high or too low, disables charging of the battery.
How to tell if the battery is charging:
— If the analyzer is On, the lightening bolt is displayed in the battery icon.
— If the analyzer is Off, the LED below the On/Off Button slowly flashes orange
with increasing intensity.
— If the analyzer is in Standby, turn the analyzer on and observe the battery
icon.
The battery charges much faster up to 70% of its full charge than it does above
70% of full charge.
Battery Life
When a battery is new, an instrument should operate for about four hours on a
fully charged battery. The actual time will depend on operating mode and
temperature.
As a battery goes through charge/discharge cycles, its capacity will decrease.
A typical battery will have more than 70% of its initial capacity after 200 full
discharge cycles when operating at 20 to 30 ×C ambient temperature.
Keysight N9912A Service Guide 5-19