Keysight E4419B EPM Series Dual-Channel Power Meter, Battery Operated, 9 kHz to 110 GHz, –70 dBm to +44 dBm

The battery option (001) allows the E4419B power meter to be used in operating environments where there is no convenient access to an ac power source. With the battery option installed and the power meter connected to an ac power source, the meter operates from the ac source and the battery runs in a controlled charge mode.
If the meter is power-up under battery power, or if the ac power is lost while connected to an ac source, a pop-up window displays the message "Running Under Battery Power".

• Typical operating time: up to 2.5 hours with LED backlight on; up to 4.0 hours with LED backlight off (E4419B power meter).
• Charge time: 2 hours to charge fully from an empty state; 50 minutes charging enables 1 hour of operation with LED backlight on; 35 minutes charging enables 1 hour operation with LED backlight off. 
  Note: The power meter is operational whilst charging.
• Service Life: (to 70% of initial capacity at 25°C): 450 charge/discharge cycles
• Chemistry: Nickel Metal Hydride