Change First Alert 1039940 Smoke Detector Battery: Expert Guide To Replacement [Updated On- 2025]

To change the battery in the First Alert 1039940 smoke detector, follow these steps: 1. Remove the detector from the wall or ceiling. 2. Open the battery compartment. 3. Take out the old 9V battery. 4. Insert a new 9V battery, ensuring correct placement. 5. Press the test button for 15-30 seconds to check safety.

After replacing the battery, reattach the smoke detector to the mounting bracket. Test the smoke detector by pressing the test button. A loud alarm indicates that the unit is functioning properly. Regularly changing the battery helps ensure your smoke detector operates effectively.

By following these steps, you maintain a crucial safety device in your home. A working smoke detector significantly reduces the risk of fire-related incidents. Understanding the importance of maintenance is essential. Next, we will discuss the signs your First Alert 1039940 Smoke Detector may need replacement rather than just a battery change.

# Table of Contents

How Can You Identify the First Alert 1039940 Smoke Detector Model?

You can identify the First Alert 1039940 Smoke Detector Model by checking its physical features and product specifications.

The key points to consider for identification include the following:

Model number: The 1039940 model number is usually printed on the back or bottom of the smoke detector. This number is essential for identifying the specific model.
Design: The First Alert 1039940 features a slim, round shape with a white plastic housing. This design is typical of many smoke detectors, making visual recognition straightforward.
Power source: The 1039940 model typically operates on a sealed lithium battery. Knowing this helps differentiate it from models with replaceable batteries, providing clarity in identification.
Alarm type: This smoke detector uses an ionization sensor. This type is effective at detecting fast-flaming fires but may be less sensitive to smoldering fires than photoelectric detectors.
Test and hush button: The 1039940 features a push button on the front of the device. This button allows users to test the alarm and silence it for non-emergency situations, which can aid in quick identification.
Additional features: Some units have features like voice alerts and low-battery indicators. Identifying these features helps in confirming the exact model.

By considering these attributes, you can accurately determine whether the smoke detector in question is the First Alert 1039940 model.

What Essential Tools Do You Need for Replacing the Battery?

To replace a battery, you need essential tools such as a screwdriver, a new battery, and a clean cloth.

Screwdriver (usually Phillips or flathead)
New battery (matching specifications of the device)
Clean cloth
Safety glasses (optional for eye protection)
Vacuum or compressed air (for cleaning)

Understanding the tools required helps ensure a smooth battery replacement process.

Screwdriver: The screwdriver is a tool used to remove screws securing the battery compartment. Phillips screwdrivers have a cross-shaped tip, suited for most batteries, while flathead screwdrivers have a single flat edge. Ensure the screwdriver matches the screw type in your smoke detector.
New Battery: The new battery must match the specifications of the device, such as size and voltage. Smoke detectors typically require 9-volt batteries or AA batteries, depending on the model. Consult the manufacturer’s instructions for the correct battery type.
Clean Cloth: A clean cloth can be used to wipe any dust or debris inside the battery compartment. Keeping the area clean ensures proper contact between the battery terminals and the device, which helps maintain efficiency.
Safety Glasses: Although not always necessary, safety glasses provide protection while working on electrical devices. They can shield your eyes from dust or accidental contacts.
Vacuum or Compressed Air: These tools help remove debris within the device. A vacuum or can of compressed air can clean out accumulated dust that may hinder the detector’s performance.

Incorporating these tools will facilitate an efficient and safe battery replacement.

How Do You Safely Remove the First Alert 1039940 Smoke Detector from Its Mounting Bracket?

To safely remove the First Alert 1039940 Smoke Detector from its mounting bracket, follow the steps of gently twisting the detector and disconnecting any power source if applicable.

Turn the detector counterclockwise. Hold the smoke detector firmly in one hand. Use your other hand to twist the detector counterclockwise until it releases from the mounting bracket. This will ensure that the locking tabs disengage properly.
Disconnect the power source. If your smoke detector is hardwired into your home’s electrical system, locate the wiring harness. Press the tab on the wiring harness while gently pulling it apart from the detector. Ensure that the power is off at the electrical panel before doing this to prevent any electrical shock.
Remove the battery if applicable. In the case of battery-powered models, make sure to remove the battery by pressing on the release tab, usually located at the battery compartment. This step is crucial to prevent draining battery power inadvertently and maintaining safety.
Check for any additional attachments. Some smoke detectors may have additional components, such as a base plate. If so, loosen and remove any screws or fasteners securing the base plate to the ceiling or wall before fully detaching the smoke detector.
Inspect for damage. After removal, check the smoke detector for any signs of damage or deterioration. This can include corrosion, rust, or significant wear. Regular maintenance and inspection are vital to ensure proper functionality.

By following these steps, you can safely remove the First Alert 1039940 Smoke Detector without any risk.

What Steps Are Involved in Removing the Battery from the Detector?

To remove the battery from a smoke detector, follow these steps carefully:

Gather necessary tools, if any.
Turn off the power to the smoke detector.
Remove the smoke detector from its mounting bracket.
Locate the battery compartment.
Release the battery by pressing the tab or latch.
Take out the old battery.
Insert the new battery securely.
Reassemble the smoke detector.
Test the smoke detector after replacing the battery.

Different viewpoints exist regarding the necessity of turning off the power. Some recommend it for safety, while others believe it is unnecessary if done cautiously. It is also important to note that smoke detectors vary in design, affecting the battery removal process.

Gather Necessary Tools:
Gathering necessary tools involves checking if you need a screwdriver or a specific tool for your smoke detector model. Some detectors may require tools for removal, while others use a simple twist or pull mechanism.
Turn Off the Power:
Turning off the power prevents accidental electric shocks when handling wired smoke detectors. While many modern smoke detectors have battery backups, ensuring safety is paramount during maintenance.
Remove from Mounting Bracket:
Removing the smoke detector from its mounting bracket means twisting or sliding it off, depending on the model. This step allows access to the battery compartment and is essential for all types of smoke detectors.
Locate the Battery Compartment:
Locating the battery compartment involves examining the back or side of the smoke detector. Different models may have highly accessible compartments or those requiring additional steps to open.
Release the Battery:
Releasing the battery involves pressing a latch or tab. Some smoke detectors have a pull-tab mechanism that makes it easier to handle the battery installation process.
Take Out the Old Battery:
Taking out the old battery requires careful handling to avoid any corrosion residues that may be present. Dispose of the old battery according to local regulations.
Insert the New Battery:
Inserting the new battery entails checking for the correct polarity and making sure the battery fits snugly in its compartment. Incorrect installation may lead to device malfunction.
Reassemble the Smoke Detector:
Reassembling the smoke detector involves putting it back on the mounting bracket properly. Misalignment during this step can cause the detector not to function effectively.
Test the Smoke Detector:
Testing the smoke detector ensures it operates correctly after battery replacement. Most detectors have a test button for this purpose, helping ensure safety in your environment.

By following these steps, you can maintain your smoke detector effectively and ensure it operates as intended. Regular checks and replacements contribute to household safety.

Which Type of Battery Is Required for the First Alert 1039940 Smoke Detector?

The First Alert 1039940 smoke detector requires a 9-volt battery for operation.

Types of batteries compatible with First Alert 1039940:
– Alkaline 9-volt battery
– Lithium 9-volt battery
– Rechargeable 9-volt battery

The choice of battery can impact the smoke detector’s performance, duration, and reliability.

Alkaline 9-volt battery:
Alkaline 9-volt batteries are widely used for smoke detectors like the First Alert 1039940. They are inexpensive and readily available. These batteries typically last between six months to one year, depending on usage. However, they are not rechargeable. They can leak if left in the device for long periods, which may cause damage.
Lithium 9-volt battery:
Lithium 9-volt batteries are another option for the First Alert 1039940. They have a longer shelf life and can last up to five years. These batteries perform better in extreme temperatures and do not leak as easily. Though more expensive than alkaline batteries, their longevity can make them a cost-effective choice in the long run.
Rechargeable 9-volt battery:
Rechargeable 9-volt batteries can be used with the First Alert 1039940. They can save money over time, as they can be charged and reused instead of being replaced. However, their performance may vary, and they typically have a shorter lifespan per battery cycle compared to non-rechargeable batteries. Regular charging is necessary to avoid failure during use.

Selecting the right battery type significantly influences the effectiveness and maintenance of the First Alert 1039940 smoke detector. Proper understanding of each battery type’s characteristics helps users make informed decisions regarding their smoke detector’s operation and safety.

How Should You Properly Insert the New Battery Into the Smoke Detector?

To properly insert a new battery into a smoke detector, first, ensure that you have the correct type of battery, usually a 9-volt or AA battery, depending on the model. Remove the smoke detector from its base by twisting or sliding it, and then open the battery compartment. Insert the new battery, ensuring that the positive terminal aligns with the positive indicator. Close the battery compartment firmly and reattach the smoke detector to its base.

Many smoke detector batteries are designed to last between 6 months to a year. It is recommended to test the smoke detector monthly to ensure functionality. An estimated 30% of smoke detectors fail to work because of dead or missing batteries. This statistic highlights the importance of regular maintenance and battery replacement.

For example, in families with young children, ensuring that smoke detectors are functioning properly can significantly enhance safety. A household that checks smoke detectors every month and replaces batteries annually tends to have a much higher safety level compared to those who neglect these tasks.

Environmental factors can also influence battery performance. For instance, extreme heat or cold can decrease battery life. Therefore, detectors located in garages or near heating/cooling vents may require more frequent battery changes.

In summary, to insert a new battery into a smoke detector, follow the steps of removing the unit, replacing the battery correctly, testing for proper function, and considering environmental effects on battery life. Regular maintenance is crucial for optimal safety. Further exploration could include understanding different types of smoke detectors and their specific requirements for battery installation.

How Can You Reattach the Smoke Detector After Battery Replacement?

To reattach a smoke detector after replacing its battery, simply align the detector with its mounting bracket, press down until it clicks into place, and twist or slide it securely, ensuring proper function.

To elaborate on the process of reattaching the smoke detector, follow these steps:

Align the Smoke Detector: Ensure the smoke detector is facing the correct direction. The mounting bracket should line up with specific notches or grooves on the detector. This orientation is crucial for securing the device properly.
Press Down: Gently press the smoke detector onto the mounting bracket. You should hear a click when the connections securely engage. This click indicates that the device is locked into place.
Twist or Slide: Depending on the model, you may need to twist or slide the smoke detector to complete the reattachment. For twist models, rotate the detector to align it with the locking mechanism. For slide models, pull the detector down into its final position until it is snug against the bracket.
Check Functionality: After securing the smoke detector, test its functionality by pressing the test button. A successful beep will indicate that the smoke detector is properly installed and operational.
Regular Maintenance: It is essential to replace batteries at least once a year and to test the smoke detector monthly. According to data from the National Fire Protection Association (NFPA, 2020), functioning smoke detectors reduce the risk of death in a fire by 50%.

By following these steps, you can ensure that your smoke detector is securely reattached and ready to provide safety for your home.

What Steps Should You Follow to Test the Smoke Detector After Replacing the Battery?

To test the smoke detector after replacing the battery, follow these steps:

Ensure the replacement battery is installed correctly.
Press the test button on the smoke detector.
Listen for an alarm sound.
Check the LED indicator lights (if available).
Repeat the process for all smoke detectors in your home.

These steps ensure that your smoke detector is functioning properly. Now, let’s explore each step in detail.

Ensuring the Battery is Installed Correctly:
Ensuring the replacement battery is installed correctly is critical. The battery should fit snugly and be oriented according to the positive (+) and negative (−) markings. A poorly connected battery can prevent the smoke detector from operating.
Pressing the Test Button:
Pressing the test button on the smoke detector evaluates its electronic circuitry and sound mechanism. When pressed, the alarm should sound immediately. If it does not, the smoke detector may be malfunctioning.
Listening for an Alarm Sound:
Listening for an alarm sound confirms that the smoke detector is operational. A loud, piercing sound indicates that the unit is working as intended. If the sound is weak or lacking, further investigation or replacement may be necessary.
Checking the LED Indicator Lights:
Some smoke detectors have LED indicator lights that signal their status. A green light typically means the unit is functioning correctly, while a red light might indicate a malfunction or low battery. Refer to the manufacturer’s instructions to interpret light signals accurately.
Repeating the Process for All Smoke Detectors:
It’s important to repeat the testing process for all smoke detectors in your home. Different smoke detectors may possess varying functionalities and requirements. Regular testing ensures comprehensive safety coverage in all areas of your home.

In conclusion, follow these steps diligently to ensure the reliability of your smoke detectors after changing the battery.

How Often Should You Change the Battery in the First Alert 1039940 Smoke Detector to Ensure Safety?

You should change the battery in the First Alert 1039940 smoke detector at least once a year to ensure safety. This recommendation stems from the need for reliable performance in detecting smoke and fire. Regular battery changes help maintain the device’s functionality. Additionally, you should test the smoke detector monthly by pressing the test button. This practice checks whether the smoke detector is working correctly. Following this routine supports your safety and enhances the effectiveness of the smoke detector in emergencies. Always refer to the user manual for specific guidelines and recommendations.

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