This machine not only operates as a battery tester for 1.5v and 3v button batteries, but can also test power for watch batteries before you open them.
If it is low battery, the machine will make a sound with lighting, which doesn't keep in synchronism with the watch. These all will warn a customer in advance that their watch requires a new battery.
If a quartz watch requires a new battery or is broken and need to be repaid, you can find it out with this tester before opening the watchcase.
This tester can check mechanical defects and shortage of voltage level. The tester is effective to test 1.55V silver oxidized as well as 3V lithium battery, mercury and alkaline button batteries.