You can check your battery level at any point by clicking the Menu button or checking it in the MYVUSE App. When your battery level reaches 30% and then 10% the device will vibrate to remind you to charge.

When your battery level is very low you will no longer be able to puff until you charge your device. When the battery level is close to 0% the device will shut down, and the screen will not respond until you charge the device.