MacBook Pro Battery Health Waning Quickly – But Why?

I usually leave my MacBook Pro sitting on my desk connected to a power adapter. Since I had the battery replaced back in October 2008, my guess is that I may have cycled through a power charge at the most 10-15 times.

However, this past week I had my MacBook Pro out and about around the house way more than usual. I would use the computer on battery a bit, then recharge it when I was done. Stuff like that. But, most of the time, even this week, I would still use the MacBook Pro connected to a power adapter.

So, yesterday (4 April 2009), I used iStatPro (highly recommended widget) to check the health of my battery. It was at around 96% after about 20 cycles. I didn’t think this was too bad. Before I went to bed, I noticed my batter was down to about 35% as I had been using it untethered to my power adapter. So I shutdown the computer, plug it into the power adapter and then went to bed.

This morning (5 April 2009) I woke up to the strangest thing. I noticed the light to my power adapter was *off*. No green light to mean the battery was charged. No red (or is it orange?) light to mean that the battery was charging. Nothing. So I removed the adapter from the MacBook Pro and plugged it back in; then the light went on as to indicate it was charging.

When I booted the computer up, I noticed the battery still had only 35% charge. What the heck? I had it plugged in all night. So I brought up iStatPro again, and here is what I found (except replace the 100% with a 35% because I just took this snapshot right now)

69% health after only 21 cycles!!!!! No way that is normal.

Then I opened up System Profiler and found corroborating evidence.

I tried resetting the SMC, but that didn’t help.

So what is going on here? I must be doing something wrong, right?

Will calibrating the battery help me or am I just screwed and going to have to bring the battery back to the Apple Store again for replacement?