A couple days ago I was surprised to see my Macbook sitting at an odd angle. When I lifted it up, I was dismayed to find the battery pack had burst open. Up til then, the battery (about five years old) was still working reasonably well.

When I took apart the battery, it's clear one of the cells had inflated like a balloon. Anybody know what causes this? Apparently it's pretty common for this machine. Is it inherent in all Li-Ion batteries? This failure mode would be Really Bad in most iPad/Pod/Phone devices, where the battery is wedged between solid aluminum and a glass screen.

At any rate, I've ordered a 3rd party clone battery (about $70). Reviews indicate they're no worse than the "genuine" Apple part, and cost half as much.