It's also critical to tell your tenants if that alarm starts going off, don't just pull the batteries.

I've looked into this and found an interesting read about how Tesla/Solar City is a threat to utilities because you can use a Solar Roof/Solar City installation and a Tesla Powerwall battery to store excess energy and sell it back to utilties.

The vendor will then contact you directly to schedule a time for service.If for some reason you don't have access to your online portal, you can call our main office, hit the prompt for maintenance and then you will be automatically directed to our 24 hour maintenance team.Just a reminder regarding maintenance, that AC Filters should be changed every thirty days, and smoke detector batteries should be changed at least once a year.Your new home has been professionally inspected prior to you taking occupancy, and a copy will be sent to you once received from the inspector.

@Quynh-Chi Nguyen,Contact the company, and ask them to send you a replacement cover, i'm guessing it was making a noise and they removed the batteries-- can you ask them if they know where it is?  

RR Do you promise even when humans are permanently wired to the Machine network and being used as batteries for the proliferation of Machine consciousness?  

It has an internal battery backup.

Batteries died in the thermostat (I'm not kidding; this has happened twice with two tenants and they couldn't read the "low battery" warning on the thermostat).  3.

Used to was that if all the switches were left in the right positions and they still conduct current, you could tow a sunken submarine to recharge its batteries, raise it if there's no air pressure t blow the ballast and run the pumps to re-float it.

Damage happens, things break, screws get lose, leaks occur, mold forms, batteries die, filters need replacing. 

We switch the battery out once a year, gives us a good reason to come over and just check stuff out.