Today I raked leaves at my flip that is for sale, worked in marketing of a vacant unit, wrote a list of things that need doing in order to clear my furnished rental, to make it ready to rent empty - scheduled Occupation Inspection with the city; changed batteries in the thermostat so that my tenant has heat.

For insurance inspections check all your smoke detectors are present and have batteries, check railings are secure.

(ie, tenants are responsible for changing water filter elements, fridge filters, furnace filters and smoke alarm batteries.)

I believe most/all Simplisafe systems have a 24-hour battery backup. 

Some of them will reset to 12:00 and no program when the lights go out; some will handle short outages but not long ones; some of them have a battery and will keep time even with long outages. 

I offered to stop by the same day (last time the battery needed to be replaced in the thermostat) but he said it was not a good day for him.

One low-key method I like to use is to schedule a visit to change the batteries in the smoke detectors.

WiFi is very battery intensive, so I highly recommend that you use Z Wave or ZigBee.

Electrical not up to code and smoke detectors (not a big deal w/ battery install) definitely warrant some negotiation as they aren't obvious to the typical home buyer.

The safest setup would be to have hard-wired smoke and CO detectors with sealed battery backups.