It appears that batteries are not currently spawning in .57 Stable. I asked on the official forums as well as everyone's favorite subreddit, and no one else seems to have had any luck, either.
I don't recall seeing batteries spawning in the last several weeks of Experimental patches, either (except for the freshie battery, of course).
Since the freshie kit no longer includes a battery, this renders all battery-operated devices in the game useless.