Guys and gals, I�ve just finished my multimedia playback battery life tests.
Exactly the same tests, conducted under exactly the same circumstances (static and same placement, disabled 3G, no Net connections / programs running in the background, no Bluetooth, lowest backlight; no incoming / outgoing phone (call, SMS etc.) activity; factory earbuds with 70% volume level and exactly the same set of WMA�s, in the same order) that yielded in 5:26 total playback time (from being topped up battery to the handset entirely shutting down) with the v12 ROM, now, resulted in 7:55 total playback time with the new, v20 ROM.
That is, the low-CPU multimedia playback battery life has been increased by 45% !!!! This means it�s true what the Nokia folks have claimed: that is, they have implemented far better scaling (underclocking) than in previous firmware versions.
I�ll repeat the tests with A2DP to see whether the improvements are similar, or, does A2DP result in a significantly less battery life gain.
(For my v12 results, see http://www.howardforums.com//forum/thread/1273334/ ; you might want to read others� results at http://www.howardforums.com//forum/thread/1282983/ too)
EDIT (11/29/2007 4:53 AM CET): as promised, I've made some serious A2DP battery life tests with the new firmware version (as has been done previously with the old one).
Unfortunately, with A2DP enabled, there is not any battery life increase when playing back WMA files using the built-in Music Player. Playing back the same WMA files, the battery life has turned out to be exactly the same (5:02) as with the previous tests. This means that, while previously the difference between the wired and the wireless case wasn't very big (about 9%), now, it's 57%.
This may be caused by A2DP's switching the CPU into the same speed than previously, unlike with the simple wired playback, where the CPU may operate at a lower frequency (with the new fimrware version) than previously.
I'll try to make MP3 tests too as the built-in Music Player has significantly higher CPU usage with both playing back WMA (let alone thorugh A2DP). With MP3, the CPU usage is significantly lower (with A2DP enabled, still (!) lower than WMA without A2DP) - I'd like to see whether this does result in a significantly better battery life with the new firmware version.
EDIT (12/02/2007): some VERY thorough battery life tests have been published with the new, v20 firmware at http://www.allaboutsymbian.com/forum//forum/thread/67175/#post350782 . Don't forget to check it out!