This is something we are working to improve but not to worry it's normal. The battery level gets updated several times a day when it is connected with your phone. If your bottle recently glowed or sent data over the battery level can appear to be less than if the battery level is measured when the bottle hasn't been in use. The battery level will decrease over time. If you increase the amount of glows to more than 3 times a day, you will see a decrease in battery life.