Sony VGC-RA825GY - Manual (Page 77)

About the Lithium Battery
The lithium battery starts to weaken after several years and the system settings, such as the date and time stored in
CMOS RAM, may become inaccurate. Replace the lithium battery when this occurs.
There is danger of the battery exploding if it is replaced incorrectly. Replace the battery only with a
CR2032-type lithium battery.
Page 77