Processor power increases exponentially. Hard drive storage increases exponentially. And the energy density in batteries? Decidedly not exponential. Lithium ion batteries are thought to be nearing their technical limits, and alternatives are still probably a few years away.
I thought about this the other day when I was working at my local coffee shop. On the table in front of me I had both my fancy smartphone and my ancient MP3 player, which is what I was listening to. Because, frankly, I don’t trust my phone to have enough juice to make it through the day if I use it for frivolous things like playing Plants vs Zombies. Or listening to music.
Streaming music over the 3G network, is incredibly energy-intensive – like talking on the phone constantly. Rhapsody and Spotify have figured this out, unsurprisingly, and their iPhone apps enable you to download playlists of music to your phone over WiFi. (With an average speed of 22 Mbit/s for an 802.11g network, you can download a 5 min song at a bitrate of 128 kbit/s in just a couple of seconds, so you don’t need to spend long in a hotspot.) But having a bunch of playlists on tap is still pretty far from true streaming music.
Given a constant energy density, of course, one option is just to make the battery bigger. And my coder friends tell me that clever programming can help a lot with battery life. But for smartphones, we really just need much better power sources before the promise of whatever you want to listen to, whenever you want it, wherever you are, can become a reality. Dear materials scientists and electrical engineers, please get right on that, will you?
Thanks to Mark Chang for some technical background to this post; any misapprehensions are entirely my fault, not his.
Image: New Battery Generations, from the Argonne National Laboratory, posted here under its Creative Commons license. How freaking cool is that?
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