Hi; I've been researching this topic myself after struggling with the Dell Power Manager app.  Actually, the DPM app will allow you to set an upper charge limit setpoint like you want to do but will not indicate any alarm as you desire.
Have a Dell 7706 and want to limit the charging of the battery to 80% yet also want to be able to change it back easily.  Would also like an alarm at 40% if it is unplugged.  I would like one app that can do all that preferably free  
Battery life