there is a later version of xbatt online http://www.clave.gr.jp/~eto/xbatt/
xbatt uses APM which seems to be a by now deprecated predecessor of ACPI. If I can trust Wikipedia with this [1] "the last fully functional APM support shipping in [Linux] 3.3". So xbatt is some shape of zombie already, I suppose. I have bumped the ebuild nevertheless. +*xbatt-1.3_rc1 (05 Aug 2015) + + 05 Aug 2015; Sebastian Pipping <sping@gentoo.org> +xbatt-1.3_rc1.ebuild: + Bump to 1.3_rc1 (bug #556682) + [1] https://en.wikipedia.org/wiki/Advanced_Power_Management