Sony VAIO PCG-R505TE Service Manual page 45

The battery indicator light on the front of the notebook indicates the status
of the battery pack.
Battery Indicator Light
Battery Pack
(supplied)
Battery Indicator
Light Status
On
Single blink
Double blink
Off
✍
Both the battery and power indicators blink when the battery is running out of power.
Meaning
The notebook is using battery power.
The battery is running out of power.
The battery is charging.
The notebook is using AC power.
Connecting a Power Source
Battery Indicator
23