I've got an Alpha Master Chrony that suits me well. I like to have the display on the bench where I can see the string develop as I shoot. It takes a nine-volt battery and I always keep a fresh battery in the box that the chrony is stored in. When I start seeing error messages I know to change the battery.
Oh, and one thing about chronographs. There are only two kinds of chronograph owners. Those who have shot their chrony, and those who will shoot their chrony. The folks at Chrony won't laugh at you, and will send out another box
tuit suit.
Forewarned is forearmed.