Minimize Window Bug
I tried Version 2.1 of BatteryMon and there is a bug when minimizing the window. If you select Minimize to system tray only and deselect Show icon in system tray, then minimize the window or click on the Show Desktop icon, BatteryMon disappers. It's still running in the background, but there is no way I've found to bring the window back. It doesn't show up in the Applications list in Task Manager, but it does in the Process List.
The only reason I had the options configured that way was because I thought the mini mode and the tray icon were redundant. I don't think you should force Show icon in system tray if Minimize to system tray only is selected though. Maybe you could automatically switch to mini mode if the minimize button is pressed and leave BatteryMon on the taskbar if Show Desktop is clicked. That is how other programs work, like Newsbin and eMule, because you usually just want to get to an icon on the desktop when you click Show Desktop, not minimize the window.
Thanks for bringing this to our attention, we'll make a note about this for future updates.