A lithium-ion rechargeable battery holds a specific number of charges. If you drain the battery completely every time you use your Beoplay H9 3rd Gen, you can expect approximately 400 charges before the capacity goes below 80% compared to a new battery.
A partial discharge reduces stress and prolongs battery life. This means that if you do not fully discharge the battery, you may achieve up to several thousand charging cycles.
We, therefore, recommend charging your Beoplay H9 3rd Gen when necessary, e.g. every other day, and storing them in normal room temperature when not in use.