I put in my lease that I will be replacing the furnace filter, batteries for smoke detector/CO detector, and inspecting the unit every 6 months.

This morning I heard the low battery churp from the alarm upstairs so I came home after work with fresh batteries. 

I would assume if yours are hard wired they will be going off often and if battery the batteries will be removed the first day.

The fire hazard from lithium batteries is no different from the fire hazard in cell phone batteries, lap top computers, high-end flash lights, or power tools.We do not allow smoking but do allow vaping.

Neighbor is on probation for drunk driving and has a record of battery.

The best bang for buck are those laptops with a 256gb SSD drive and long battery life. 

The first property we had inspected is in great shape and we were asked to fix a handrail and replace a battery in a smoke detector( simple $150 charge for the inspection and $20 for me to fix).

My guess is they were in a hurry and skipped the scan or they had a bad battery or some reason it didn't get picked up.

Calling Florida Power and Light, told me I am caller number 475, please wait patiently, and my cell phone had 30% battery left, with no way to recharge. 

I replaced the batteries at the controller near the bedroom and it worked.