I'm on my second swelling battery in 3 years. The last one was only bought new 14 months ago. I've used the laptop without wall charge a handful of times. But without the battery in the laptop you run the risk of total disconnect in the middle of something. Frankly, I think this is a design fault. I've never seen anyone else have to replace their batteries on their non-apple laptops. This is looking like a yearly charge. Thank again Apple. Your stuff ain't so great - but we sure pay triple for it.