sandertel

Hi everybody, Reading the article on rebuilding ones own laptop battery pack I have some questions. I have a Compaq Evo N400c laptop with a 14,4V 2150mAh battery pack. It's label says it is a 4 cell pack. Some clculations: 14,4V /4cells = 3,6V per cell (which is the industrie standard from what I understand) = perfect !!! Now, the thing is when the laptop is off the powergrid (which the battery pack only can keep up for several seconds - maybe 5 or so) A mowning/crackling noise comes from the battery pack area. It sounds a bit like an old amp which hasn't been proparly grounded (a sort of 50Hz noise) Even if the laptop is switched off and not plugged in into the mains power it makes this 50Hz type noise. I assume (so it seems) this noise is produced by the safety electronics or individual cells in the pack. It seems the sound derives from the connector area... No idea what this means... Before I will attempt the 4 Li-Ion cell replacement I like to know if replacing the cells will rid me of the noise. Do degraded/broken battery packs make such a noise ussually ? Are the cells or the safety electronics inside the pack at fault here - Guesstimate ??? Or maybe is the safety electronics damaged or just reacting to broken cells in the pack? Please advise.. Regards, Sander Tel.