Smoke Detectors: When to Replace, Not Just the Battery

TL;DR: Smoke detectors have a hard expiration date, usually 10 years from manufacture, printed on the back of the unit. A new battery won't extend that lifespan. If your detector chirps constantly after a fresh battery, or you can't find a date stamp at all, replace the whole unit.

_Last reviewed: July 2026 · 6 min read_

You changed the battery last month and it's still chirping. That's not a battery problem, and it's a sign the alarm itself has aged out. Here's how to tell the difference between "needs a battery" and "needs to go in the trash."

Okoniq Property Hub logs the install date and manufacture date for every smoke detector in your properties, so you're never guessing which units are due for replacement.

How Long Do Smoke Detectors Actually Last?

Most smoke detectors are rated for 10 years from the date of manufacture, not the date you installed them. The sensing chamber degrades over time as dust and small particles build up, and after a decade the sensor can't reliably detect smoke even with a brand-new battery inside.

Check the back or side of the unit for a manufacture date stamped into the plastic, usually formatted as MM/DD/YYYY or just the year. If you can't find a date, or the unit predates 2015, replace it rather than guessing. This matters more in rentals: landlords in most states are legally required to keep working smoke detectors in every unit, and "the battery was fine" won't hold up if an inspector finds a 14-year-old alarm on the ceiling.

Battery Swap or Full Replacement — Which One Do You Need?

A battery swap fixes low-power chirping; a full replacement fixes an expired sensor, cracked housing, or a unit that keeps false-alarming no matter what battery you put in. Test both by pressing the test button. If it beeps loud and clear, the electronics are fine and you likely just need a fresh battery. If it beeps weakly, doesn't respond at all, or chirps within a day of a new battery, the detector itself has failed.

| Symptom | Battery Fix | Unit Replacement | |---|---|---| | Intermittent chirp every 30-60 seconds | Yes | No | | Chirps again within 24 hours of new battery | No | Yes | | Manufacture date over 10 years old | No | Yes | | Yellowed, cracked, or discolored housing | No | Yes | | Test button gives weak or no sound | No | Yes |

This is the same logic that applies to a lot of home systems people patch instead of replace. Just like knob-and-tube wiring that technically "still works" but has aged past safe service life, an old smoke detector can pass a casual glance while quietly failing at its one job.

Are Sealed 10-Year Battery Units Actually Better?

Sealed units with a built-in 10-year lithium battery are worth the extra $15 to $25 upfront because they remove the battery-swap variable entirely. These units are designed to last exactly as long as the sensor does, so there's no risk of an owner replacing the battery and assuming the alarm is now good for another decade. When the 10-year mark hits, the whole unit chirps and gets replaced together.

For rentals with multiple units, this also cuts down on maintenance calls. A tenant calling about a chirping alarm at 2 a.m. is a common complaint, and sealed units reduce how often that happens since there's no battery to go stale independently of the sensor. If you're already tracking electrical upgrades like 2-prong to 3-prong outlet conversions, smoke detector swaps are a natural item to bundle into the same maintenance pass.

What About Interconnected or Hardwired Smoke Detectors?

Hardwired smoke detectors still expire after 10 years even though they're wired into your home's electrical system rather than running on battery alone. Most hardwired units include a backup battery for power outages, and that battery does need periodic replacement (typically every 1-2 years), but the detector head itself is on the same 10-year clock as a battery-only unit. Don't assume "hardwired" means "permanent."

If your home was built before major code updates required interconnected alarms (where one going off triggers all of them), and you're not sure whether your electrical panel can support an upgrade, it's worth checking your service capacity. Older homes on 100 amp service can usually still handle hardwired smoke detector circuits, but it's a good moment to have an electrician glance at the whole panel while they're there.

How Do You Track Replacement Dates Across a Whole House or Rental Portfolio?

The easiest system is writing the install date directly on the unit with a marker and setting a calendar reminder for year 9, giving yourself a buffer before the hard 10-year cutoff. For a single home this is simple enough with a sticky note in a junk drawer. For landlords managing several units or multiple properties, a spreadsheet or a dedicated maintenance log works better, since state law in places like California and New York holds owners to specific documented alarm testing intervals, not just "we think it's fine."

Photograph the manufacture date stamp when you install a new unit and keep it with your property records. If a tenant ever disputes whether an alarm was working, or an insurance adjuster asks after an incident, that timestamped photo is far more useful than a memory of "I think we changed it a few years back."

FAQ

How often should smoke detector batteries be changed?

Standard 9-volt batteries should be changed at least once a year, commonly done during daylight saving time changes in spring and fall. Sealed 10-year units don't need separate battery changes at all.

Do smoke detectors expire even if unopened in the box?

Yes, the clock starts at the date of manufacture printed on the unit, not the date of purchase or installation, so a detector sitting in storage for 3 years only has 7 years of useful life left once installed.

Can I test a smoke detector without pressing the button?

Pressing the test button is the reliable method since it checks both the alarm sound and the circuit; some people use actual smoke from a blown-out candle, but this only confirms the sensor detects particles, not that the full alarm system works correctly.

How much does it cost to replace a smoke detector?

Basic battery-powered units run $10 to $20, sealed 10-year lithium units run $20 to $35, and hardwired interconnected units typically cost $25 to $45 per unit plus electrician labor if you're adding new ones to a circuit.

Are landlords required to replace smoke detectors on a schedule?

Most states require working smoke detectors at move-in and during routine inspections, and several states, including California, specify maximum ages or require replacement upon a manufacturer's expiration date being reached. Check your specific state and local fire code, since requirements vary by jurisdiction.

This is educational information, not fire safety or legal advice. Consult a licensed electrician for hardwired installations and check your state and local fire code for specific landlord requirements.