I have a smoke detector in my condo and I've changed it before quite easily myself and its just a battery replacement for $5 or so.

I think it is a great goal because it allows us to work hard for something and then take a mental pause, relax, and recharge we could all do at some point in the year when we need to take a beat and recharge the battery. 

The gas engine only charges the battery/electric motor.Very reliable - no issues after 30,000 miles so far.Battery is holding up quite well.  

They work like a charm and battery operated.

I once had a brand new car that kept draining batteries.  

Provide a safe and clean space for tenants, take pics when you install (every 10 years) or change batteries on smoke/carbon detectors, have them sign off on a movein doc that says windows open, smoke detectors, test.

Batteries and Pharmaceuticals are great examples.Looking at the flow of shipping containers, it's going to be a while until China will be able to get back into the bulk export business, even if they magically get their workers back to work.

They can get battery operated wifi cameras for a reasonable cost.

Regarding battery replacement, Nissan has been replacing Leaf batteries in the $5000 range, not $40,000.

I have had my MacBook Air for 5 years, and just literally replaced the battery, 2 weeks ago.