On the alarm sensors, it comes down to use. I’ve had the alarm since inception. so about 20 months. I’ve replaced one battery on our back sliding door sensor in that time. It gave me a low battery signal, I ordered them on Amazon and switched it out within 48 hours, no problems. All the rest have been fine. Doorbell, again based on use. I have one on battery in my garage and it gets about 5-8 weeks depending on how much we go in and out.
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