Battery level and heartbeat are uploaded too frequently

[Panosfunk]

Yuan was looking at the uploaded data from the Ubilife study and we realized that the battery level and the heartbeat is uploaded very often. Not sure if this is something that needs changing or not. @bardram ?

[bardram]

Battery events are generated from the OS via the battery_plus plugin. Here, we cannot control how often we get a battery event.

[bardram]

Heartbeat is done every 5 minutes to any connected device to check if it is (still) connected. Hence, we get this only when the device is connected.

Maybe another solution may be to try to monitor connection and disconnection events and report on these instead?