I had my 305 give a low battery alert when I turned it on today. 2nd time in a year after recharging that I've seen this. So I ordered the Gomadic charger today.

I am not clear on why my battery was low. I connect it to my computer to d/l the data after each ride and charge it fully. It normally keeps a charge for a very long time (months).

Is it possible that the display can be off but the 305 still powered up? I turned it off, plugged it into the computer and it began charging. At some point I uploaded the data but never turned it back on. I got the charge completed msg and then unplugged it. That's the only thing I can think of that would have drained the battery after being charged less than a week ago before trying to use it today.