I just updated the firmware on my 305 yesterday. It wasn't holding a charge for longer than 2.5 hours, and the good folks at Garmin recommended that this MAY fix the problem. I made sure to download all of my ride data first, which is good, since it was all reset as part of the update.

The good news is that I ran the unit for 8.5 hours yesterday, so it seems to have solved my problem!

SheFly