A few weblogs ago, I noted an occasion where my iPod seemed to run through its battery very quickly. I had attributed this to a faulty battery meter, but instead it turns out to have a different root cause.
A reader comment to my "A Week With the iPod" article noted that when playing very large MP3 files, the hard drive doesn’t spin down. This wrecks havoc with the iPod’s battery saving strategy of reading 20 minutes of data at a time and not spinning the hard drive much.
Interestingly enough, the day I noticed that my battery faded faster than it should have was just after I had started ripping entire mix CD’s down to one MP3 file so that I could avoid the artificial gaps between tracks that I noted in my iPod review. Turns out that my work-around for the gap problem creates 60 to 90 MB files that run smack into this problem of not spinning down the hard drive when playing back large files.
To verify the issue for myself, I performed an informal test to see how fast the battery drains when the hard drive is constantly spinning. I took a fully charged iPod and set it playing an MP3 of a John Digweed album that I had ripped from the original CD as one track (remember, Don’t Steal Music). After playing two CD’s worth of data, I had exhausted half of my battery. A rough estimate based on this test puts battery life at something much less than 5 hours — half of what the iPod is capable of with normal size tracks.
I do have to say that I’m impressed that the iPod can keep the hard drive spinning that long. The new lithium polymer battery technology works very well indeed. I wonder how long my Titanium would run using this new battery technology.