Microsoft has released the Windows 10 Mobile preview build 14342.1004 for members of the Insider program who are in the Slow ring.
As with its previous release to Fast ring Insider members a few days ago, this preview build for Slow ring Insiders contains mostly bug fixes compared to the Windows 10 Mobile preview build 14342. In particular, this build fixes a battery life issue that was affecting some devices while also causing them to get hotter than normal.
Update: Microsoft has updated its blog post with this note:
We are aware of issues with some apps such as Microsoft Health running in the background causing higher than normal battery drain.