I'm not a fan of the sleep cover, there are plenty of magnetic objects in my world. Still they seem to work for some.
With such battery use I would wonder if the suspend function were introducing a loop, that is consuming some power. If we were at Github, I would suggest swapping out "suspend.sh" with the ones in KSM and Sergey's Launcher. If one of them solves the problem, it would do a lot to identify the needed fix. (Sergey's latest version appears to have fixed
a similar problem for another poster.)
You might want to see if making sure the WiFi is turned off before using suspend, makes a difference.
Luck;
Ken