There was a very good explanation and fix for this problem located at...

http://www.rioworld.org

However they had a hacker attack and lost the info. I have a printout and will retype the post here. This procedure helped to calibrate my Riot. Constant battery drain is just “life.” Upgrading the firmware to 1.25 may help a little but not much. The problem is probably a battery “memory” issue. If this doesn’t work and you need a new battery you might want to start here….

http://www.panasonic.com/industrial/battery/oem/chem/lithion/index.html

Calibration procedure per “Rio Expert”

1, The player need to be used until you get this message: “Battery almost empty. Connect wall charger to continue,”

2, Leave the player turned on, and plug it into the charger.

3, After a 6 or 7 hour charge the player will then need to be used until “low” appears where the battery bar is. At this point the player will be calibrated and ready for regular use. If it isn’t:

Drain the batteries again and perform a full recharge to calibrate it again. Now that’s double calibration.

Calibrating the batteries improves battery life, Double calibrate, one calibrations after right after the other generally does it each and every time.