Laptop beeps when charging?

I have a Acer Aspire 7735z laptop that only beep once its charging. The beeping is coming from the laptop and not the charger itself. It beeps in intervals and the blind dims and goes back normal really fast. Is there anyway to halt the beeping when its charging without putting the volume on mute. This noise is piss ME off and I volition belike have nightmares about it. Please help!!!!!!!!!!!!!