This awesome tester does more than just test watch batteries (which it does very well, thank you). It can also perform a battery test on quartz watches without opening the back! I know! That can be a real time saver!
Here's what the Renata Watch & Battery Tester can do: You can test loose watch batteries, both 1.55v silver oxide and 3v lithium batteries. Select the correct battery voltage on the side of the tester. Then place the loose battery on the testing plate on the front and press down on the metal testing prong. The analog gauge will give an indication of the strength of the battery.For quartz watches, you can place the watch case on the top testing place and press the "watch test" button.
If the quartz watch is getting power from the battery, the tester will beep and flash in a regular interval. The signals will be every second for quartz watches with second hands. The intervals will be longer, but regular, if there is no second hand. The interval can be as long as a minute so be patient when checking. How useful is that?