Ember's battery life depends on a number factors, but we can expect the battery to last about 2 hours on the go with a set temperature of 130°F (54.4°C). Battery life will vary depending on pour temperature, ambient temperature, and desired temperature.
The data used in this graph were under these conditions: Pour temperature of 170°F (76.6°C), Ambient temperature of 72°F (22.2°C), and 2 ounces of cold creamer added after.