If alarms are battery-powered, there must be documented records of periodic maintenance.

The building has no house panel, so installation is going to be expensive any way you look at it.My question here is are the older battery powered detectors "grandfathered", or will I need to upgrade the detectors immediately.

My tenant used a battery jumper cable end and an alligator clamp to run juice from the overhead wires and around the electric meter.

ie tenant is responsible for checking the smoke detector battery every six months..

My other reason was battery life.

(ie.. the doors open, the windows work, the furnace works, and smoke alarms are functional with 10yr batteries).  

When I charge $5 for a bulb or battery for a smoke detector don't complain.

(had to tighten a hand rail, replace the two pumps on the furnaces, put batteries in the fire detectors (I forced them to rewire the fan and lights in the bathroom).Its a pain dealing with an unmotivated seller, and a real estate agent that relies on email to get anything done (especially with the city (when repairs were done, told me that main inspector was sick, and underling was doing inspections and that he was emailing back and forth about getting the rein spection, It took one trip to the city hall in person for me to get the place inspected the next day)).None of this would of happened if I hadn't had the code to the lock box.

Same for smoke detector batteries.

I have found too many surprises while reconditioning a rental to not take the 30 days.