That sounds so logical, it must be true, right? 
The Battery Model claims to be 10 year (obviously a larger capacity than the AC model which contains a back-up - that module does have cautions against not having AC Power Connected or it WILL soon deplete and issue warning)
- I hear what you’re saying but would have to think the radio cannot be constantly active, employs some kind of low power mode? HIGHLY speculative on my part here - Maybe the transmitter only kicks on when alarm is triggered and the receiver has a low-power listening mode? I’ll have to try to find more details on that.