If you play music at moderate volume levels, the battery in your Beoplay E8 3rd Gen can support up to 7 hours of playtime. For the Beoplay E8 3rd Gen, a fully charged case provides 4 extra earphone charges. With the 4 extra charges, you will have up to 5 charges (including the first charge) and the equivalent of up to 35 hours of playtime when on-the-go.
In general, the battery life depends on the volume, intensity of music and equalizer settings. This means that the battery drains faster at higher volume when playing higher intensity music like rock or heavy metal.