I’ve managed to go a few days without writing about the nano… but that’s over now. Why? Well, I’ve been trying to figure out what the real world battery life is with this device.

The Apple tech specs list nano battery life as 14 hours when fully charged. I consider these specs in the same light as I do “miles per gallon” on car stickers… with a big grain of salt. So I figured my nano should get around 10 hours per full charge.

But my feeling was that the 4GB iPod was getting much less than 10 hours. Seemed like every few days I’d notice the red battery icon. I don’t listen to that much music. Before jumping to conclusions, I decided to do a little formal testing. I had a road trip this weekend to shoot a wedding. The drive was four hours each way — perfect nano testing conditions.

As a side note, I have to say that I think the nano is the best sounding iPod I have. After listening to it shuffle though a variety of songs, I was impressed that many of my favorites sounded new again on this device.

Anyway, under controlled conditions that let the nano play song after song, I’m happy to report the battery performed better that I thought it would. I discovered what I think was a key factor to my previous misconception: I wasn’t putting the nano to sleep in between listening sessions. It seems that it continues to draw substantial juice when not playing. I knew this in theory from my other iPods, but the effect wasn’t as noticeable on them, especially my shuffle (which seems to play forever on a charge).

I’m not sure that putting the nano to sleep was the key to better battery life. Maybe I was just losing track of time. I’m still testing in real world conditions. If you’re not already using the sleep function on the nano, you might want to give it a try. See if you notice an improvement in battery performance.