Spectrum Masterâ„¢ MS271xE User Guide : General Information : Instrument Care and Preventive Maintenance : Battery Replacement
 
Battery Replacement
The battery can be replaced without the use of tools. The battery compartment is located on the lower left side of the instrument (when you are facing the measurement display). To remove the battery:
1. Slide the catch toward the bottom of the instrument.
2. Pull the top of the door away from the unit.
3. Lift out the battery door.
4. Pull straight out on the lanyard to remove the battery pack from the instrument.
Note 
When inserting the battery, the battery label should face the back of the instrument and the end where the battery contacts are located slides in first. If the battery door does not latch closed, the battery may be inserted incorrectly.
Battery Compartment
The battery that is supplied with the Spectrum Master may need charging before use. The battery can be charged while it is installed in the Spectrum Master by using the AC-DC Adapter, or outside the Spectrum Master with the optional Dual Battery Charger. Refer to Symbols and Indicators for a description of battery symbols.
Note 
Use only Anritsu Company approved batteries, adapters, and chargers with this instrument. Anritsu recommends removing the battery for long-term storage of the instrument.
Caution 
When using the Automotive Power Adapter, always verify that the supply is rated for a minimum of 60 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.