n900 Battery Duration: Ogg vs. MP3

There have always been complaints about Ogg being more of a battery hog on the Nokia tablets compared to Nokia optimized MP3. I decided to measure the difference.

All tests were run on a preproduction n900 device that Nokia distributed at the Maemo Summit. The software is the Maemo5 41-10 release which was already installed in the device. I installed Ogg Support, gst-av, ffmpeg and OpenSSH. Otherwise the device is the default 41-10 release. WLAN connection was configured but not activated during the tests. A SIM card was in place only in the SIM idle test.

Before every test I charged the device, disconnected the charger once I noticed the green led, and rebooted the device. After the boot I started a simple script in the xterm. The script logged current time to a file, run “sync” command and slept 60 seconds after which it started the loop again.

Idle tests

I run two idle tests between the libvorbis and ffvorbis tests but I’ll introduce the idle results first.

First idle test was a generally idle device. I.e. it did have the default processes running but I didn’t start anything, except my logging script. During the test I did check a couple of times if the device was still on. The battery lasted for 93.8 hours.

According to Igor Stoppa, there’s a cellmo sw bug that makes current higher without a SIM card. Therefore I rerun the idle test with a SIM card inserted. During the test I received two phone calls which I hung up, I received two SMS messages and wrote one. At one point the notification led was blinking for 45 mins. The battery laster for 93.6 hours.

There’s probably a few hour error margin on those tests, so basically the battery lasted roughly a bit over 90 hours in both tests.

Powertop shows that after 60 seconds of showing the xterm with display blanked, the CPU is mostly in the highest C4 sleep state: