Kidde Firex I4618 Hardwired Ionization Smoke Detector
- Power Source: Corded Electric
- Sensor Type: Ionization
- Alarm: Audible
- Product Style: Hardwired Smoke Detector
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A sensible replacement pick for a home already wired for interconnected Kidde alarms, given the 24-device interconnect capacity and battery backup.
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ASIN: B008SE0LLIModel: I4618Category: Smoke Detectors & Fire Alarms
Overview
The Kidde I4618 (model 21007584) is a hardwired ionization smoke detector with battery backup, built to interconnect with up to 24 compatible smoke, CO and heat alarms across a home.
This is a hardwire, AC/DC direct-wire unit meant to interconnect with other Kidde alarms rather than stand alone, which makes it fit best as a like-for-like replacement in a house already wired for an interconnected system, not as a simple battery-only add-on.
- Hardwired AC/DC power with battery backup
- Interconnects with up to 24 devices (18 initiating)
- Alarm memory LED flags the triggering unit
- Front battery pull tab for access without unmounting
Who it's for
Homeowners replacing a hardwired smoke detector in a house already wired for interconnected alarms. Not a fit for someone who wants a simple standalone battery-only detector with no household wiring involved.
Pros and cons
- Battery backup keeps it working during a power outage
- Interconnects with up to 24 devices for whole-home coverage
- Alarm memory LED flags the unit that triggered first
- Front battery pull tab allows access without unmounting the unit
- No review data available to confirm long-term reliability
- Ionization-only sensing suits fast flaming fires better than smoldering ones
- Hardwiring makes installation less simple than a battery-only unit
Performance notes
Because it wires into AC power with a battery backup, the alarm keeps working through a power outage, and the interconnect wiring triggers every linked smoke, CO or heat alarm at once. An alarm memory LED flashes on whichever unit first detected the alarm condition, which helps identify the source room in a multi-unit system.
Specifications
| Brand | Kidde |
|---|---|
| Model | I4618 |
| Dimensions & fit | |
| Item Weight | 21.6 pounds |
| Capacity & performance | |
| Upper Temperature Rating | 100 °F |
| Power & efficiency | |
| Power Source | Corded Electric |
| Construction & materials | |
| Enclosure Material | Plastic |
| Color | White |
| Compatibility & installation | |
| Compatible Devices | Up to 24 Kidde devices |
| Included components | |
| Unit Count | 1 |
| Warranty & support | |
| Manufacturer Warranty Description | 10-Year Limited Warranty |
| Other details | |
| Sensor Type | Ionization |
| Alarm | Audible |
| Product Style | Hardwired Smoke Detector |
| Number Of Items | 1 |
| Mfr Part Number | 21007584 |
| Builtin Media | Alarm(36), Mounting Hardware (36), User Manual (36), Wiring Harness (36) |
| Item Type Name | Kidde i4618 Firex Hardwire Ionization Smoke Detector With Battery Backup |
Closest rivals on specs
First Alert SC9120B Hardwired Smoke and CO Alarm 2 Pack- Item Weight 21.6 vs 1.3 pounds (+1562%)
X-Sense SC07 Smoke and Carbon Monoxide Detector Combo- Item Weight 21.6 vs 1 pounds (+2060%)
First Alert SMICO110 10-Year Smoke and CO Alarm- Item Weight 21.6 vs 0.7 pounds (+2986%)
Frequently asked questions
How many devices can the Kidde I4618 interconnect with?
Up to 24 devices total, of which 18 can be initiating alarms, including smoke, CO and heat alarms.
What happens to the Kidde 21007584 during a power outage?
Its battery backup keeps it operating so it isn't disabled when household power drops.
Can I change the battery without removing the Kidde I4618 from its mount?
Yes, a front battery pull tab allows battery activation and access without taking the unit off its mounting bracket.