Now I just make sure it's in lease that they know they're responsible for light bulbs and batteries (amazed at how many think I'm coming over to change a light bulb for them due to prior apartment living.)

There are some areas that are now requiring the landlords to change batteries annually by ordinance - the 10 year battery is not exempted.

I'll also add that I have asked 3 pediatricians in 2 different regions about the occurrence of Lead poisoning and was able to learn of one case, in which both parents of the child worked in a battery factory where lead exposure was common.

There was a great BP thread on this a long time ago. http://www.biggerpockets.com/forums/52/topics/68041A few things I've been doing lately: smoke detectors w/ 10 year batteries, glue drain assemblies under kitchen and bath sinks (high fail rate with junk screw pvc), removing storm doors, also going to ad a storm door addendum.

And, as to equipment you can add in any overhaul or reconditioning that extends the life or performance since it is no longer just a 1982 John Deer 15kw generator, so the higher purchase can be justified.IMO, it's best to try to assign values to other assets than carry a large sum for good will for the reason Charles pointed out.

I'm very familiar, have helped design and build carbon fiber plastics on some this worlds best aircraft like the B-2, F-35, Boeing Dreamliner (structure, not battery lol)....It is amazing what happens in the tech world by accident.

What batteries?

when I buy a 24 pack of paper towels at costco and a 48 pack of toilet paper and AA batteries and coffee pods, tide pods, dish soap, cascade pods, light bulbs, etc. then we just bill the owner for it (marked up slightly to account for our purchase and delivery) and then stock the supply closet on site with the supplies.

@Aaron Gordy and both tunneling project rumors and filed permits for battery production is likely foreshadowing of even more growth for the area.  

My crystal ball is out of batteries.