RepOne Sensor is equipped with a 2000mAh battery, that's almost as big as the battery in most phones. If used responsibly, your device can last as long as a month on one charge. 

We've made a tool you can use to estimate battery life based on your use. You can find it here. Make a copy of the spreadsheet and feel free to play with the numbers and see where it lands.

Firmware version v0.6.X, estimated to ship September 2020, will come with improved power management, battery % indication, low power indication, and more power features. Until these arrive we suggest charging every few sessions.