First Alert SMI100 Battery Smoke Alarm
- Power Source: Battery
- Sensor Type: Ionization
- Alarm: Smoke
- Product Style: Precision Detection
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A straightforward battery smoke alarm for anyone who wants easy installation and simple upkeep without electrical work.
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ASIN: B0CJLN45JZModel: SMI100Category: Smoke Detectors & Fire Alarms
Overview
The First Alert SMI100 is a battery-operated smoke alarm using First Alert's Precision Detection sensing, built to meet current industry standards for reducing cooking-related false alarms while still catching real fires early.
This is a battery unit rather than a hardwired one, so installation is just mounting and inserting a battery, no electrician or wiring needed. A front-access battery compartment and an end-of-life warning are the two features aimed squarely at keeping upkeep simple over the years.
- Battery operated smoke alarm
- Precision Detection sensing
- Front access battery compartment
- End-of-life warning
Who it's for
Good for a homeowner or renter replacing an aging smoke alarm or adding coverage to a room where running new wiring is not practical. Anyone wanting whole-home interconnected hardwired alarms should look at a hardwired First Alert model instead.
Pros and cons
- Battery operated, no wiring required
- Front access battery compartment for easy swaps
- End-of-life warning built in
- Precision Detection sensing reduces cooking nuisance alarms
- Smoke detection only, no carbon monoxide sensing
- Runs on a replaceable battery rather than a sealed 10 year cell
Performance notes
Precision Detection sensing is tuned to meet newer industry standards aimed at cutting down nuisance alarms from cooking smoke while still responding to genuine fire conditions. The front-access battery compartment means swapping the battery does not require removing the whole unit from its mount, and an end-of-life warning signals when the alarm itself needs replacing rather than just the battery.
Specifications
| Brand | First Alert |
|---|---|
| Model | SMI100 |
| Dimensions & fit | |
| Item Weight | 0.6 pounds |
| Item Dimensions D X W X H | 5.6 × 5.6 × 1.9 inches |
| Power & efficiency | |
| Power Source | Battery |
| Construction & materials | |
| Color | White |
| Included components | |
| Unit Count | 2 |
| Other details | |
| Sensor Type | Ionization |
| Alarm | Smoke |
| Product Style | Precision Detection |
| Number Of Items | 2 |
| Mfr Part Number | SMI100 |
| Builtin Media | 9V Alkaline Battery |
| Item Type Name | Smoke Alarm |
| Item Highlight | SMI100 |
Closest rivals on specs
Universal Security Instruments MI106S Hardwired Smoke Alarm- Item Weight 0.6 vs 0.49 pounds (+22%)
Frequently asked questions
Does the First Alert SMI100 detect carbon monoxide?
No, it is a smoke-only alarm and does not include CO sensing.
How do you replace the battery in the SMI100?
The battery compartment is front-access, so it opens without needing to remove the alarm from its mounting bracket.
Does the SMI100 warn you when it needs to be replaced?
Yes, it has an end-of-life warning that signals when the alarm itself, not just the battery, is due for replacement.