The battery of the VitaBit sit/stand tracker is a lithium battery which will only need 1,5 hours to recharge and has a 90 days standby time 90 days. The charger is in the box and needs to be plugged into an usb-port.
The app will notify you when the trackers power is below 10%. By clicking the tracker icon on the dashboard you will be able to find the remaining battery life, this information is from the last time you have synchronized with the tracker.
Normally during the connection process the light on your tracker will blink, if you can not connect with your tracker from the APP and the light is not blinking a possible solution can be to put the tracker in the charger it can be 0%.
When charged for 100% then the light will stop blinking and be on.