Have you searched the forum for this? There are quite some threads about the battery. In particular, this could be caused by this Wifi issue
[quote=“joekafka, post:153, topic:11491”]
The extent to which Google is present is disturbing. Google is a nasty company and it’s sad that Fairphone chose to embrace that road, but I guess they have their reasons …
[/quote].
Do you want to get rid of all Google stuff? In that case, the FP team announced the release of an open-source version of the FPOS without any Google apps or services and it is rumored to be released in the first quarter of 2016. You could also consider compiling this yourself from source code, if you feel confident enough.