This is a very common problem on the Edge 205 adn 305. Riding along and the unit shuts off for no apparent reason. Unit will turn back on and work normally. I install a hardware fix for this. It is a permanent fix, unlike using spacers and other poor advice out there on the internet.
This battery is the slightly better than the stock battery.
This battery is rated a bit higher than the stock battery and performs better than the stock battery. Garmin Edge Garmin Forerunner 305 205.