MacBook Pro 17" Late 2008 Battery Failure

The battery is the original, just over 4 years old.

The battery was OK when the MacBook Pro was put into its
Tom Bihn Vertical Brain Cell over six weeks ago. The laptop sat unused and at room temperature the whole time.

When I removed the laptop on January 3, 2013, the battery had expanded. It took higher than normal force to release the latches, then the battery pushed itself partially out. I didn’t have to use excessive force on the battery to finish getting it out.

Luckily, the battery did not leak and did not catch fire, it has no burnt electronics smell. After removal I checked the laptop carefully, there was no damage! It’s been working without any issues.

The pictures show the battery exactly how it was removed, it was not pried apart. This battery has expanded more than other failures I’ve seen. I don’t know if this is atypical or if I just haven’t seen enough failures...

The pictures were taken at the same time using the camera’s flash. I did only basic Photoshopping to enhance the image’s contrast and shadows.