How long will a battery last in a Garmin GSC 10? My relatively new Garmin GSC 10 Speed/Cadence unit has started losing connection to my Garmin 500. I'm assuming that the battery is running out, since I'm still using the original that came with it. I have done about 35 hours of riding. 

So I am wondering: how long should a CR 2032 battery last? 

I know this is a little subjective and will depend on ambient temperature and to a lesser extent speed and cadence for transiently illuminating the LED each pedal stroke/wheel revolution. But generally, how many hours can I expect to get from a battery?
Right now I am at 159 hours of riding time on the battery which came with my GSC-10.

Garmin's stated battery life for the GSC-10 is 1.4 years at one hour of riding per day which works out to 511 hours. (See page 51 of the Edge 500's Owner Manual)

On the interweb I've come across two different suspected causes for low battery life on the GSC-10: 


Some (mostly older?) GSC-10's are susceptible to corrosion due to incomplete sealing of the circuit board inside the GSC-10. If this occurs battery life is shortened due to an internal short which causes the battery to drain more quickly than normal. 
If you store your bike with either the cadence or speed magnet lined up with the sensor, the GSC-10 may not go to sleep after a short period of inactivity like it is supposed to. This seems to result in faster than normal battery drain.