Ibook battery and strange sounds

[skinniezinho]

Hi guys,I have 2 doubts:
First one,when my ibook is fully charged (and turned off) it makes an annoying noise,is this normal?as soon as I power it up the sound disappear.
Second,my battery did some strange thing,it shuts off @30% sometimes 40%,but it shows 92% health and lasts 2/4hours,in an attempt to do something I tried a routine of discharging and full charging it,and it had been earning mah lol..is this possible?why does it happen?can it be because it was not very used by the last owner?
here it is a screenie:


istat says the same..
Do I have a very good battery,or one that in a few days is going to heaven?lol it is very strange...

 

[Reflow]

Try reseting the PMU. As for the strange sound what do you have it near. Anything electronic. If so try moving it to a different area.

 

[skinniezinho]

Try reseting the PMU. As for the strange sound what do you have it near. Anything electronic. If so try moving it to a different area.

I have already reseted the pmu and the pram.
The sound,it makes it on my house,and in my school so,can it be dangerous?(charger exploding or something)?