Here's what I measured on my Cowon D2.
D2 4GB Power Consumption With All Music In A Transcend 16GB SDHC.
16GB Transcend SDHC Curent Consumption From Data Sheet:
The current consumption is measured by averaging over 1 second.
- Before first command: Maximum 15 mA
- During initialization: Maximum 100 mA
- Operation in Default Mode: Maximum 100 mA
- Operation in High Speed Mode: Maximum 200 mA
- Operation with other functions: Maximum 500 mA
Durability: 10,000 insertion/removal cycles
Music: mixed of 320, 256, 192, & 128 kbps, all MP3s.
IEM - ER4p, 27Ohms nominal.
Power on all the time, continuous music playing.
Vol - varied from 16 - 26.
Video Display - 15secs On.
Brightness - 9.
3 bars left after ~6hrs & 30mins
2 bars left after ~12hrs & 20mins
1 bar left after ~20hrs
Battery indicator all red and flashing after 22hrs.
Low battery and shuts down after 23hrs.