Bug? Boinc set to run only off battery, also runs when charging. (LG P880)

[[WHGT]Cyberman]

I know it's a weird idea, but I've decided to let Boinc only run off the battery. Boinc + Charging heats up the device way too fast and much. Even if only 1 core is working.
Boinc alone, off battery, even with 4 cores the phone doesn't heat up half as much :-(

Anyhow, even though only the battery is checked as power source, it doesn't stop working when connected to the charger (USB).

Regards,

Christoph