Site Master™ S331L User Guide : General Information : Instrument Description : Battery Information
 
Battery Information
The batteries that are supplied with the Site Master may need charging before use. They can be charged using either the AC-DC Adapter or the DC adapter. Refer to Status Tool Bar for a description of battery symbols. The batteries are charged in the instrument and only removed for replacement.
Note 
Use only Anritsu-approved batteries, adapters, and chargers with this instrument.
The batteries will charge at a faster rate when the instrument is turned off or is set to standby mode. Charging the batteries while the instrument is running will take a longer time to reach a full charge.
To prolong the useful battery life, the internal charging circuit monitors each battery’s temperature. Normal charging occurs when the battery temperature is between 0 °C and 45 °C. Charging is paused if the internal battery temperature is beyond this range.
Caution 
When using the Automotive Cigarette Lighter Adapter, always verify that the supply is rated for a minimum of 40 Watts @ 12 VDC, and that the socket is clear of any dirt or debris. If the adapter plug becomes hot to the touch during operation, discontinue use immediately.
The Site Master batteries are installed at the factory and can be replaced by the user. Refer to Battery Replacement for information on replacing the batteries. The batteries are charged with the included AC/DC adapter.
Note 
Anritsu Company recommends removing the battery for long-term storage of the instrument.