When most people think of CR2 batteries they think of the batteries that are used in cameras. And in most situations, that is indeed the case. Along with CR123 batteries, CR2 batteries are some of the most popular batteries for use in photography equipment. But many security cameras have taken a liking to these small batteries as well. They are occasionally used in smaller security sensors that need a reliable source of power. While many users will never encounter these batteries, they are sometimes needed for certain applications.
The good thing about the CR2 batteries is their small size. They aren't quite a small as coin batteries, but they are more compact than most other cylindrical batteries, such as AA batteries and AAA batteries. This gives them a unique niche for powering certain sensors. However, since the CR2 batteries are still relatively small, the devices that use them are usually on the smaller side. We recommend using lithium CR2 batteries, as they will provide a longer power life than alkaline batteries.
CR2 batteries aren't super common in the security industry, but they do have a few applications. For instance, some Wireless Honeywell 5800 Series Sensors have been known to use these batteries. Some examples include the Honeywell 5870API Wireless Indoor Asset Protection Sensor and the Honeywell 5800SS1 Wireless Shock Sensor. While these sensors aren't some of the most commonly used devices, they do serve as proof that CR2 batteries are needed in certain security applications. It's good to keep some around.