Model # 21008051

Internet #100051755

Store SKU #182262

Store SO SKU #198092

Kidde Battery Operated Ionization Smoke Alarm


Battery Operated Ionization Smoke Alarm

  • Compact design
  • Test button
  • Ionization sensor
$4.98 / each
If you buy 6 or more
$4.66 / each
store icon Loading Buying Options...
package icon Loading Buying Options...
Sorry, but we ran into issues loading these options. Please try refreshing.

Frequently Bought Together

Product Overview

Homedepot Image

The Kidde i9040 Battery-Operated Ionization Smoke Alarm is a single-station alarm with an early warning signal. This alarm utilizes ionization sensing technology to activate in the event of a smoke or fire incident and its compact, 4 in. design lends it a discreet profile in your home or business. Powered by a 9-Volt battery, this smoke alarm will protect you, your family and home during a power outage. When the battery begins to lose power, a low-battery alert will begin to chirp to notify you it is time to replace.

  • Utilizes ionization sensor
  • Provides an early warning signal in the event of a smoke
  • Compact 4 inch Design
  • Low-battery indicator chirps to alert you to change the battery
  • Test button tests the unit's electronic circuitry, horn and battery function
  • Battery power means protection during power outages
  • 9-Volt battery included use Kidde power supply (205976052)
  • 9 Volt Zinc Battery Included
  • Note: product may vary by store
  • UL/CSFM Ref. Kidde Part I9040
  • Click here for more information on Electronic Recycling Programs

Info & Guides

You will need Adobe® Acrobat® Reader to view PDF documents.  Download a free copy from the Adobe Web site.

Customers Also Compared These

$4.98 /each
$7.67 /each
$7.94 /each
Name Battery Operated Ionization Smoke Alarm Battery Operated Smoke Alarm Battery Operated Ionization Smoke Alarm with Test Button
Brand Kidde First Alert Kidde
Ratings (271) (9) (40)
Power Source Battery Battery Battery
Alarm Sensor Type Ionization Ionization Ionization
Alarm/Detector Features No Additional Features No Additional Features Hush Feature
View Product View Product View Product



Product Depth (in.)
Product Height (in.)
Product Width (in.)


Alarm Sensor Type
Alarm Type
Alarm/Detector Features
No Additional Features
Commercial / Residential
Commercial / Residential
Connector/Contact Type
Pack Size
Power Source
Voltage (volts)

Warranty / Certifications

Certifications and Listings
1-UL Listed

More Products With These Features


Customer Questions & Answers

Are there a lot of false alarms for the explosive gas component of model KN-COEG-3?

Asked by: SuzyQ
My experience after 2 months of use is NO false alarms....I have located it in a small furnace room that contains both a natural gas furnace and natural gas water heater. As for placing it in the furnace room when the instructions say not to place in furnace rooms--It was my only common sense option in the raised ranch home.-----In any event if i had a gas leak and had placed the detector in an upstairs location or down stairs bedroom far from the furnace and incoming gas lines It may be tooooo late as the gas would never reach the detector in time.... Am I missing something by placing It in the furnace room for earliest possible detection of a gas leak? Agan,I have had NO false alarms and like the units, but you must take time and educate yourself thru the instructions.
Answered by: ROCK
Date published: 2017-05-27


I have propane heat in a room in my garage. I never knew that you had to have a combination detector to have it to detect a propane leak. This unit does detect propane leaks? Just want to be sure before in purchase.
Asked by: Randy
Answered by: Bigruss
Date published: 2017-02-07

Is this a smoke alarm and Carbon Monoxide detector?

Is this a smoke alarm and Carbon Monoxide detector? looking for the least expensive Carbon Monoxide detector, need 20 for my apartments
Asked by: Jackie
No, have to get separate co detector. Our city code requires them to be in different places anyway.
Answered by: Longbeachkenny
Date published: 2015-11-11

what is the life in years of the detector?

Asked by: oooo
10 years
Answered by: raj22
Date published: 2017-07-03
  • y_2017, m_8, d_18, h_12CST
  • bvseo_bulk, prod_bvqa, vn_bulk_1.0.0-hotfix-1
  • cp_1, bvpage1
  • co_hasquestionsanswers, tq_89
  • loc_, sid_100051755, prod, sort_[SortEntry(order=NUM_ANSWERS, direction=DESCENDING), SortEntry(order=SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=LAST_APPROVED_ANSWER_SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=LAST_APPROVED_ANSWER_SUBMISSION_TIME, direction=DESCENDING), SortEntry(order=BEST_ANSWER_FEEDBACK_COUNT, direction=DESCENDING), SortEntry(order=POSITIVE_ANSWER_FEEDBACK_COUNT, direction=DESCENDING), SortEntry(order=NUM_ANSWERS, direction=DESCENDING)]
  • clientName_homedepot
  • bvseo_sdk, java_sdk, bvseo-3.1.1
  • CLOUD, getContent, 98ms

Customer Reviews

Battery Operated Ionization Smoke Alarm is rated 4.4 out of 5 by 271.
Rated 5 out of 5 by from 5 Star Review Rating provided by a verified purchaser
Date published: 2017-04-04
Rated 5 out of 5 by from 5 Star Review Rating provided by a verified purchaser
Date published: 2017-05-01
Rated 5 out of 5 by from 5 Star Review Rating provided by a verified purchaser
Date published: 2017-04-04
Rated 5 out of 5 by from 5 Star Review Rating provided by a verified purchaser
Date published: 2017-04-22
Rated 5 out of 5 by from 5 Star Review Rating provided by a verified purchaser
Date published: 2017-04-05
Rated 5 out of 5 by from 5 Star Review Rating provided by a verified purchaser
Date published: 2017-04-04
Rated 5 out of 5 by from Great product, works as descripted. Great product, works as descripted.
Date published: 2017-05-02
Date published: 2017-05-17
Rated 5 out of 5 by from Cheap price and it does the trick... Cheap price and it does the trick
Date published: 2017-08-15
Rated 4 out of 5 by from The detector was easy to assemble... The detector was easy to assemble
Date published: 2017-04-08
Rated 5 out of 5 by from Good product for the price. Good product for the price.
Date published: 2017-03-28
Rated 3 out of 5 by from Supplied battery was dead. Supplied battery was dead.
Date published: 2017-07-11
Rated 5 out of 5 by from great product worked well great product worked well
Date published: 2017-05-16
Rated 5 out of 5 by from They work as expected.... They work as expected.
Date published: 2017-06-20
Rated 5 out of 5 by from Easy to install... Easy to install
Date published: 2017-04-08
Rated 1 out of 5 by from Bad... Bad
Date published: 2017-08-02
Rated 5 out of 5 by from So far so good! We've had ours installed for about 2 weeks, which comes with lots and lots of peace of mind because we recently had a gas leak in our house and never knew we needed a gas detector instead of just a carbon monoxide detector. The price is high, but you can't put a price on peace of mind. We haven't had any false alarms yet like other reviewers have complained about. We also haven't had any issues with the 9 volt backup battery like others have. Seems to be a good product so far! EVERYONE WHO HAS GAS RUN TO THEIR HOUSE NEEDS TO HAVE ONE OF THESE! We had a low level gas leak in our house that was making me sick, so I will never ever live without one of these again.
Date published: 2013-01-02
Rated 5 out of 5 by from A good value and it works I purchased this unit after my wife woke me up and told me she thought she smelled gas. After being up the rest of the night assuring her she didn’t I drove to Home Depot and picked up this combination Gas/Carbon Monoxide detector unit. I tested it with an open gas valve and it works well. The alarm emits a very loud piercing blast that is sure to wake up even the soundest sleeper. Having an alkaline 9 volt battery (included) backup; it can be unplugged and moved from room to room for testing. You can plug it right into a 110 volt outlet or slide out a built in stand and sit it on the counter. I have used a Nighthawk Carbon Monoxide detector for several years with no problems. In my opinion this combination unit is a very small price to pay for a good night of sleep.
Date published: 2015-06-26
Rated 5 out of 5 by from Excellent value I have installed more than 10 of these in several locations and they have been in service for over a year now. These run on single 9V battery which is included with the package. These are UL listed so meet the required standards. I really don't see the point in buying the more expensive ones unless you need dual power supply i.e. the 120V and 9V.
Date published: 2012-07-16
Rated 5 out of 5 by from Excellent unit - no issues after several years of continuous use We purchased this detector a few years ago, and have had no issues with it since. Last night, the gas detector went off. I couldn't smell the odorant in the leaking gas, but I still shut off the flow and called the gas company. They found two small leaks, and were surprised that the unit detected the gas levels found. I previously owned a Nighthawk CO detector (no gas detctor), and it performed quite well.
Date published: 2013-08-08
Rated 4 out of 5 by from Worked when I needed it to. This alarm went off twice and both times it detected a very small gas leak in the old house we were living in. The gas leak was small, and the gas specialist assured us that it was so small it wouldn't even have been an issue, but the fact is, this detector caught it. I've been happy with it and it makes me feel safer. I have a First Alert detector as well, and that one didn't go off when the Kidde Nighthawk did.
Date published: 2011-11-29
Rated 1 out of 5 by from Stay away!! These detectors have been a headache starting 30 days after install. The batteries need to be changed. Constant false carbon monoxide alarms. I've had a licenses plumber/heater determine there are no gas leaks. I've also had the fire department conclude the alarms are faulty. There is nothing setting them off. It seems the batteries leaked after only 30 days of use and now unless I change them every 30 days I have false alarms. It's stressful on my tenants and on me since I am a long distance landlord and bought these for peace of mind but all they do is deliver the opposite, noise and stress. Completely unreliable. Pick a different brand.
Date published: 2016-08-26
Rated 5 out of 5 by from This Product Saved Our Lives!!! Recently, our home was hit by lightning. The lightning ran along the ductwork in the house and punctured holes in the adjacent flexible gas lines. Without this detector, we wouldn't have known so quickly that there was explosive gas filling the basement, and we could have had a very bad outcome. There is no doubt in our minds that this product saved our lives. If you have any gas appliances in your home, this is a must!
Date published: 2006-09-03
Rated 4 out of 5 by from Kidde CO Detector with Battery Back-Up Very easy to install, just plug into an outlet. The first one we purchased was defective. The alarm would constantly go off even when the digital display said zero and no carbon monoxide was in the air. We knew there was no carbon monoxide present because we had another CO detector that did not go off. The alarm is a very high pitched sound that awakens you immediately. We know because it would often sound in the middle of the night. We finally called the manufacturer and they asked us for the serial number. They said it was defective and told us to throw it away. They sent us a new one that we have had no problems with.
Date published: 2006-06-02
Rated 5 out of 5 by from This product is a must have. The product has Night Hawk technology which our fire dept suggest a carbon monoxide alarm have. It is easy to read, has a battery back up and is reasonably priced. We have one in our lower level, main level and upstairs level of our home. The carbon monoxide/gas alarm combination is the best way to go.
Date published: 2014-03-04
Rated 4 out of 5 by from Size doesn't matter. The description clearly states "compact design". It works just as well (maybe better) as larger units but requires less space to install. It's a smoke detector, not a manhole cover. I have several of these in my home and have no complaints. They are easy to install and maintain. Battery life has been satisfactory. No surprises.
Date published: 2014-01-13
Rated 5 out of 5 by from Well worth the money Bought this because my boys bedroom was being built close to the furnace. Didn't expect it to go off the minute I plugged it in. Turns out there was an issue with the furnace. Awesome product, a true life saver.
Date published: 2014-10-01
Rated 4 out of 5 by from Light is flashing- must be working Economical , small unit with no frills does the job with no issues so far. Just what Is needed.
Date published: 2016-03-29
Rated 5 out of 5 by from Good value/quality Picked up one of these today for a bedroom in a small 3 bedroom (occupant sleeps with door closed) ranch house today. It currently accompanies two First Alert units in the beginning/end of the hallway (photoelectric near kitchen/livingroom and ionization at the end towards the 3 rooms). This smoke alarm is just as well built as any comparable First Alert and has a small footprint while being lightweight which makes it a perfect candidate for a ceiling mount unit. The installation was cake, drill two holes, mount the bracket, and make sure battery is installed and away you go! While being a basic/entry level smoke alarm it has some decent features such as a hush button, a safety tab mechanism that insures the battery is installed (or unit will not lock into bracket), and my personal favorite an led that blinks every 40 seconds to insure the unit is receiving power. At 5 dollars, this is a very solid smoke alarm that just works. I would recommend this to anyone looking for a basic ionization smoke alarm to supplement other units for added safety.
Date published: 2012-07-02
Rated 2 out of 5 by from Drains battery I assumed the battery was for back up but I guess that uses it all the time even when it's plugged in. You have to replace the battery every two months in this thing. I come home to it beeping low battery. It's quite heavy in the outlet and can easily be knocked out of the plug. The dog knocked it intentionally out of the wall, after it battery beeped all day, when I got home it was on the ground and the dog was looking upset.
Date published: 2016-09-24
  • y_2017, m_8, d_18, h_24
  • bvseo_bulk, prod_bvrr, vn_bulk_1.0.0-hotfix-1
  • cp_3, bvpage2n
  • co_hasreviews, tv_2, tr_269
  • loc_, sid_100051755, prod, sort_[SortEntry(order=RELEVANCE, direction=DESCENDING)]
  • clientName_homedepot
  • bvseo_sdk, java_sdk, bvseo-3.1.1
  • CLOUD, getContent, 195ms