Could you confirm if this is the release version of the android service (1.0.2) or the snapshot version (1.0.3) please? If you're running 1.0.2 it might be worth checking if the snapshot resolves this as there have been a few fixes to improve battery consumption. We will be releasing that version officially in a few months after which you should be able to use it in your app safely.
Many users have reported that your app is draining a lot of power even after closing
your application, upon checking for the reason, we found that the MqttService is still running even after disconnecting the mqtt client. And because of this it keeps the device awake for a long time and thus drains the battery.