I have a 1st revision Macbook Pro 15" that's about 2 years and a few months old, and all of a sudden the battery will not provide power past approximately 76%. As soon as the the battery displays, 75% or 76% of the charge remaining, the laptop shuts off completely, does not warn me that my battery is low, and does not sleep or save the contents of my RAM - nothing it should be doing. The battery is only at 149 cycles as of today, and I don't have any sort of AppleCare plan. Is this something I can get replaced under a warranty, or would I have to shell out for a new battery? And is it even worth it?
Thanks for your help.

Thanks for your help.