Originally posted by cpoteet If I use a full battery, should I be concerned; in other words, has anyone had a battery fail during upgrade?
Don't worry too much about it. The upgrade process takes only about 2 minutes, not much chance of anything going wrong. And the camera won't let you do the firmware install if the battery doesn't have enough charge. So it's a very low risk procedure if you start with a full battery and follow the instructions.
I've done firmware upgrades several times now for K-1, same amount of times for K-5, K-3, and firmware upgrades for other cameras, plus other devices like flashes, lens accessories, GPS tools etc. Never had the procedure cause any damage.