@77alex77 I can confirm the app is not consuming battery substantially during day time, because other applications use far more battery. However, over the night, the Suunto app consumption seems to be more relevant. Before installing the Suunto App, my phone would just lose ~5% over the night, but now it loses about 10-12%. I can see Suunto App in the battery consuming list. While still distant from out of control, it is still far from ideal.
I would prefer manual synchronization rather than using more battery on phone, so I may tryout the force stop option later on.
As a side note, I am a regular user of Android Wear before and even though I sync all day long, the battery consumption on the phone seems still better.