First Alert SMI100, Battery-Operated Smoke Alarm, 2-Pack

Why I chose the SMI100 for a quick upgrade

I replaced a set of aging smoke alarms at home with the SMI100 two-pack to cover a hallway and a bedroom in one go. I wanted something uncomplicated: battery-powered, reliable, and less prone to nuisance alarms near a busy kitchen. The SMI100 fits that bill. It uses First Alert’s updated sensing approach designed to reduce cooking-related falses while still providing early warning. After several weeks of living with the pair, including a few intentional tests and some unintentional cooking mishaps, I’m confident this is a straightforward, dependable choice for most homes.

Installation and setup

Installation took me under ten minutes per unit, including removing the old plates and using the included screws and anchors. The base plate mounts with two screws, then the alarm twists on with a positive click. I appreciate the front-access battery compartment—being able to swap a battery without removing the alarm from the ceiling is a practical improvement over older designs.

The test/silence button is large enough to hit with a broom handle, and the audible test sequence is clear and loud. I could hear the alert from two rooms away with doors closed, which is what I want from a life-safety device.

Tip: label the install month/year on the housing with a marker. It makes it easy to track replacement since smoke alarms should be changed roughly every 10 years. Also, mount them on ceilings or high on walls per code guidance, and avoid dead-air spaces (like corners and near HVAC vents).

Design and build

The SMI100 is compact, lightweight, and unintrusive in white. The front battery door sits flush and opens without contortions. The plastic feels typical of residential alarms—nothing premium, but not flimsy. The faceplate is simple, with the test/silence button centered and a status LED that blinks to indicate normal operation.

It’s a basic, no-frills design; that’s a good thing here. There are no apps, no wireless modules, and no interconnect terminals to manage. If you’re replacing a hardwired system or want interconnected alarms, this isn’t the model for that. But for standalone coverage in bedrooms, hallways, and common areas, the simplicity is welcome.

Detection performance and nuisance resistance

I ran the built-in test on both units after installation and again a week later, then staged a couple of smoke scenarios. In a hallway about 25 feet from the kitchen, the SMI100 stayed quiet during routine stovetop searing with the range hood running—something past alarms haven’t always managed. When I intentionally over-toasted bread to push it, the hallway unit stayed quiet at first and then eventually sounded when the smoky air drifted down the hall, which is appropriate behavior. In a bedroom, it remained silent through all kitchen activity.

When I created a small amount of smoldering smoke from a paper test (in a controlled, safe setup), the alarm responded promptly. The response time isn’t lab-measurable in my home, but the activation was quick enough to be reassuring. The balance between nuisance resistance and early warning feels right for typical residential use.

Everyday use and maintenance

The status LED heartbeat is subtle and not distracting at night. The test/silence button works reliably, and the temporary hush function is practical for cooking-related smoke—enough time for ventilation to clear without disabling the alarm. I also triggered the low-battery chirp by temporarily using a depleted battery; the chirp is noticeable without being jarring, and the front access makes swapping fast.

Because this model uses replaceable batteries, you need a maintenance routine. I recommend testing monthly, replacing batteries annually or when chirps start, and replacing the entire unit at end-of-life (the SMI100 includes an end-of-life warning). Front-door access encourages good habits—you’re more likely to keep an alarm current if the swap takes 30 seconds and a stool, not a screwdriver and a wrestling match.

What it doesn’t do

A few limitations to set expectations:

• No interconnectivity: If one alarm sounds, others won’t automatically follow. For larger homes or multi-level spaces, interconnected alarms (wired or wireless) provide broader coverage.
• No smart features: There’s no mobile app, voice alerts, or notifications. If you want phone alerts when you’re away, this isn’t the model.
• Battery management is on you: If you’d rather not deal with battery changes, consider a sealed 10-year battery alarm. The SMI100 trades that for lower upfront cost and easy swaps.

None of these are deal breakers for the audience the SMI100 targets: people who want a reliable, code-appropriate detector that installs quickly and does its job without fuss.

Usability details that stood out

• Front battery door: The hinge and latch feel solid, and the door clears easily even close to a wall. This matters if your alarm sits near a soffit or a doorway where space is tight.
• Test/silence button: The travel is firm and the activation is unmistakable, producing the expected triple-beep test cycle. On a ceiling mount, I could actuate it with a broom handle without missed presses.
• Mounting base: Alignment tabs make it harder to cross-thread or half-engage the body. Make sure to turn until you feel the final click; a partial twist can leave it loose.

Placement guidance

Best practices apply:

• Bedrooms and outside sleeping areas are musts.
• Avoid installing directly in kitchens or near bathrooms with heavy steam. Place them nearby instead and rely on ventilation to keep nuisance alarms down.
• Keep alarms away from supply vents and ceiling corners where air may not circulate.
• For multi-level homes, put at least one on each floor, including basements.

The two-pack made it easy to cover a hallway and bedroom immediately and keep a clear plan for adding more units later.

Value

As a two-pack, the SMI100 offers good coverage at a fair price. You’re paying for core safety features—modern sensing tuned to reduce cooking false alarms, simple maintenance, and clear end-of-life signaling—without extras that drive up cost. If you prioritize interconnectivity or smart alerts, you’ll spend more on other models. For most apartments, small homes, rentals, and quick replacements, this hits the value sweet spot.

What I’d improve

• Offer an optional interconnected variant for buyers who want to expand coverage in larger footprints without moving to a different product line.
• Include clearer battery orientation graphics inside the compartment for first-time installers. It’s minor, but small friction points add up.
• Publish the hush duration and alarm loudness specs prominently on the packaging so buyers can compare across models more easily.

These are niceties, not deal breakers.

The bottom line

The SMI100 is a straightforward, dependable smoke alarm that installs in minutes, stays quiet through typical kitchen activity, and sounds decisively when it should. The front-access battery compartment and clear end-of-life warning support long-term maintenance—the keys to a smoke alarm that remains trustworthy after the day you install it.

Recommendation: I recommend the SMI100 for homeowners and renters who want a simple, battery-powered alarm with modern nuisance reduction and easy upkeep. It’s not interconnected or smart, but it nails the fundamentals—fast installation, reliable detection, and low-friction maintenance—at a price that makes outfitting multiple rooms an easy decision.