I have about every main tool Dewalt makes as well as 20 batteries.  

We bought ours for $555,000 in September 2019, have installed solar and battery ($30k) and new a/c and furnace (10k) as well as some landscaping upgrades (landscaping and artificial turf).

Squatter deactivated front door smart lock on my unit by disassembling it and removing the battery.

The deal breaker for me is that they don't work on cloudy days or at night and there aren't batteries yet to store enough of the energy, that are acceptable to me.

While I am not usually in favor of solar for a rental this may be a partial solution to your problems with a battery wall. 

I know some video door bells are battery operated so I don't have to do electrical wiring just to install them. 

Another overlooked problem is that when the backup battery gets low, it makes the alarm go off to make sure you know the battery is low.

The margins just aren't there to pay a third party to handle every minor problem I might have.While I mostly run long-term single-family rentals for families, I just answered a service call in my househack at 11:30 pm last night to change out faulty batteries in a carbon monoxide detector.

Ring cameras are good and their batteries last a long time.

so a $90 service all and an $80 capacitor fixed well over 1/2 of most issues.There are lots of issues that aren’t even that complicated… Batteries in the thermostat going dead, drain lines, getting clogged with dirt and goo, drip pans that get full from the unit sweating too much or not draining properly, bad thermostats, etc.Occasionally, you will get either a leak, or a bigger part that goes bad that will cost in the $200 to $500 range… fans and motors going out, etc.Home warranties are worthless… they will take 3 weeks to fix your AC.