How long is the life of the built-in rechargeable battery?
This will differ depending on the environment where your Walkman is used, but on average the built-in rechargeable battery can be charged approximately 500 times. The battery life becomes shorter and capacity is reduced as a result of the number of times it is recharged or used, and the environment in which it is used. When the usable battery life is half the usual time even when the battery is fully charged, the battery should be replaced.
Consult your nearest Sony dealer for more details on the life of the built-in battery.