People need electric somewhere near their slips to charge their boat batteries which always seem to die on perfect boating days. 

They run off batteries.

We also have our PM do a quarterly smoke detector battery replacement which gives us access to do a brief walk-through.

In our lease it says they are responsible for snow removal, cutting the grass, maintaning shrubs, batteries in smoke detectors etc, furnace filters, clearing out clogs they cause, and anything else that costs less than about $10 to maintain.

@Art Maydan has anyone checked the batteries?

We did install one lock( doorlock) and the battery has been good. 

With the age of the homes, you are likely going to have frequent maintenance and expensive re-conditionings between tenants (remove trash, deep clean, paint, carpet, etc.)

STOLE items out of the unit...space heater I'd allowed her to borrow, the curtain rods, a bathtub fixture...even the used AA batteries out of all the smoke detectors.You never can tell.

@Jimmy MartzJimmy, I feel it depends on the tenant base but we try to do twice a year, we do one for furnace filter replacement and smoke detector batteries and the other is considered a annual inspection.

For the top of stairways, you can get battery operated, motion sensing lights that will come on in the dark - warning guests that they are getting close to a stairway.