As you have probably learned over the years when owning different types of technology devices, some of them will be programmed to alert you when the battery is low and others will not. For the best hybrid smartwatch, if the system alerts you when the battery is about to die (which may even be present in the accompanying app) then you are good to go. However, if it does not, then it can be difficult to tell. Typically, the vibration that is used to alert you will probably no longer work and this is a good indication. Then again, if you notice that none of the markings are moving, then that is also a telling sign to get a new battery.