I think people (inc. myself) have some mixed results with Owntracks. I have also been testing EgiGeoZone (from a German developer) that now support both GeoFencing & Tracking in the same app and in a clever combination. It also posts directly to your own server instead of another party in between. Battery drain is minimal on my Nexus 6P.
I use it now in combination with Homeseer to which it connects via a plugin call PH Location. This supports multiple tracking/geofancing apps but Egi seems the most reliable. Developer is also super helpfull and quite deep into home automation. It also supports PathSense next to Google.