I get the combination smoke/CO detectors in one unit; if battery-only powered, I get the units that have a 10 year battery and warranty these days.A level of 500 is more like 100 times normal; in a house where I have a CO detector with digital readout and peak level memory, it never got above 9 over many years of service.Sounds like some of that work was not done to code; the code enforcement inspector could be called in to do what they do.

I just checked the CO detectors today and replaced batteries.

A lease may allow or require maintenance in a commercial lease, it is not acceptable in a residential lease, beyond minor issues, like HVAC filters, changing batteries in alarms or cleaning gutters.

You can also employ loud battery - powered alarms.

But to point, they were building modules for a large multi-unit complex located in Clarence NY for a rental/investment company.The build interiors were more 'high-end' given the tenant demographic they were appealing to.Their contact information is: Jamie Kline(716) 270 5526iQmodular homeshttp://www.iqmodular.com

The battery back up system has been damaged by water and not replaced.

@John Fedro   John I just did my CE for my NMLS license and one module was MH in park or out. and it was very clear they fall under Safe act and dodd frank.. 

You can also get those battery opperated alarms from harbor freight tools for under $10 and stiick them on windows.

The inspection will fail for serious items like dead battery in a smoke detector or trivial items like missing 1 screw on a outlet or switch cover plate.Faill the inspection and they will advise the tenant to move out!

My real estate agent who uses zipLogix rental lease is trying to convince me that I HAVE to use the dual powered (AC and battery) smoke detector.The lease is referring to § 9-102.