Same issue here, Roon core on a Hp T530 running linux, 128GB ssd. 8GB ram, wired ethernet to router. Local library is on a Nas and also have qobuz studio and tidal premium subs
My phone is an LG V30. It will drain 20% in an hour either using it as a remote or as an endpoint. I can play youtube music for 8 hours without it using that much.