S820E Microwave Site Master™ User Guide : Battery Replacement : 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).
Remove the battery as follows:
1. Slide the catch toward the bottom of the instrument
2. Pull the top of the door away from the instrument
3. Lift out the battery door.
4. Remove the battery pack from the instrument by grabbing the battery lanyard and pulling it out.
Replacement is the opposite of removal. The battery key side (slot below the contacts) must be facing the front on the instrument and must slide in first.
Note 
When inserting the battery, the battery label must face the back of the instrument, and the guide slot on the battery must be below the contacts. If the battery door does not latch closed, then the battery may be inserted incorrectly.
Battery Compartment
Note 
Anritsu Company recommends removing the battery for long‑term storage of the instrument.
Caution 
When using the Automotive power outlet adapter, always verify that the supply is rated for a minimum of 5 amps (60 Watts) at 12 VDC, and that the socket is clear of any dirt or debris. If the adapter plug becomes hot to the touch during operation, then discontinue use immediately.
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 require a longer time to reach a full charge.
To prolong the useful battery life, the internal charging circuit monitors the battery temperature. Normal charging occurs when the battery temperature is between 0 °C and 45 °C. Charging is paused when the battery temperature is beyond this range.