Have you ever what secrets lie in a laptop battery pack? Well I asked myself that exact question. What is inside my laptop battery pack? Well this is it (see photo above and video below). The pack is just a bunch of AA cells in a tight configuration, soldered together and packed in with some circuitry. Yep, just inexpensive AA's in a plastic casing. Why am I interested in this? My laptop battery pack used to hold about 7 to 8 hours of charge for my laptop (unbelieveable? believe it - its for the legendary IBM Thinkpad X40). Now, after 4-5 years it can only hold about 1.5 hours. So its time to find a replacement (or I can open it up and replace the internal rechargeable AA's myself if I'm brave enough). But I think i'll pass - I don't want to risk putting in a battery backwards or risking explosion while soldiering lithium batteries together. Perhaps buying a generic brand replacement would be cheaper than buying the genuine battery part.