This camera has a solar panel to keep the battery charged.

There are new developments, like the new Jeep plant going in where all of the batteries for the electric Jeep will be made.

They were on sale at Costco so I bought 2, one for the exterior door and one for the actual unit...my only complaint is that when used a lot the batteries go fast but its just a few AAs, but everything is controllable with the app, and they come with keys in case of emergency. 

Also planning to do a maintenance walk thru and deeper clean every 3-6 months where they really clean the crevices, change batteries on smart locks, touch up paint the wall dings, and other misc stuff. 

additionally I inform tenant of a maintenance inspection with 24-48 hours notice (to check smoke detector batteries, hvac filter, for any leaks) and collect evidence of smoking then.

I use their deposit to clear out the trash, my handyman likes the extra scrap recycling money, landfill & City drop off (paint, used oil, batteries, etc.) handle the rest.  

If you get a battery, you can also ensure you or your tenants have power during a blackout (which is happening more and more in certain areas). 

You know when the batteries are dying.

all our schools have already added the Tesla Mega pack batteries in prep for all Electric School Buses under the hvip program the inventives are too good to pass up for fleets and school buses. its helped our local grid stay on as we have no more backups.

Make sure your PM does an annual or semi annual inspection while changing out SD batteries, HVAC filters and does an inspection, that is what you pay them to do.