Repair Xiaomi Aqara Doorbell 2 Battery Anomaly After Firmware Patch

The Xiaomi Aqara Doorbell 2 is a popular choice for homeowners who want a sleek, wireless front‑door alert system. A recent firmware update aimed to improve its connectivity and add new features, but many users reported an unexpected battery anomaly: the doorbell’s battery indicator would quickly drop to a low level even though the device was still connected to mains power, and the motion sensor would intermittently fail to trigger. In this article we walk through the steps required to diagnose, repair, and prevent this battery anomaly after the firmware patch.

Why the Battery Indicator Misbehaves

The doorbell contains a small 3.7 V lithium‑ion cell that is meant to act as a backup when the AC line is interrupted. After the patch, several factors can cause the indicator to misreport the battery status:

• Firmware bug in battery sensing – The patch changed the way the firmware reads the voltage divider that monitors the battery level. A calculation error or wrong calibration constant can make the software believe the battery is almost empty.
• Hardware degradation – The patch also enabled a new low‑power mode that increases the depth‑first sampling of the battery. If the battery contacts become slightly oxidised or the internal resistance rises, the doorbell may see a voltage dip that the firmware interprets as depletion.
• Connector loosening – When the doorbell is removed for repair, the battery clip can become misaligned, causing intermittent contact. The firmware interprets a brief loss of signal as a battery drain.

Once the battery level drops below a threshold, the doorbell will switch to low‑power mode, turning off the camera and motion sensor until mains power is restored. That explains why many users saw the camera turn off mid‑night.

What the Firmware Patch Did

The official patch, released on March 2024, introduced:

1. Enhanced OTA update support – Allowing firmware to be downloaded directly from the Aqara cloud.
2. New low‑power sleep mode – Reducing the power draw of the camera and microphone by 40 %.
3. Battery monitoring algorithm – Replacing the old 10‑point averaging with a rolling mean of the last 20 samples.

The change in battery monitoring is the root of the anomaly. The new rolling mean is more sensitive to transient voltage drops; a single spike can shift the average downwards and trigger a false low‑battery alert. Users who had a clean, freshly installed battery saw the indicator flash from 80 % to 30 % within minutes.

Preparing for Repair

Before opening the doorbell, gather the following:

• A Phillips‑head screwdriver
• A small flat‑head screwdriver or plastic pry tool
• A replacement 3.7 V lithium‑ion battery (same capacity, 180 mAh is typical for the Aqara model)
• A clean, static‑free work surface
• A flashlight

It is strongly advised to disconnect the doorbell from its AC power source before proceeding. Even though the device still contains a backup battery, working on a powered device can damage the internal circuitry or cause a shock.

Step‑by‑Step Repair Guide

1. Remove the Doorbell from Power

1. Locate the power adapter that plugs into the wall socket.
2. Unplug the adapter from the doorbell and the wall outlet.
3. Wait for at least 30 seconds to allow residual charge to dissipate.

2. Access the Battery Compartment

The Aqara Doorbell 2 has a sealed front panel. To open it:

1. Use the plastic pry tool to gently lift the seam around the doorbell’s perimeter. Avoid metal tools to prevent scratching.
2. Once the seam is loosened, pull the front panel away in a straight line.
3. Inside, you will see a rectangular battery compartment with a small screw holding the cover.

3. Inspect the Battery and Contacts

• Battery Condition – Check for bulging, discoloration, or leakage. A damaged battery can cause voltage irregularities.
• Contact Pins – Look for oxidation or debris. Use a cotton swab lightly dampened with isopropyl alcohol to clean the contacts.
• Battery Clip – Ensure the spring clip that holds the battery in place is not bent or broken.

4. Remove the Old Battery

1. Release the clip by gently pulling on the side of the battery.
2. Lift the battery out of the compartment. Store it safely; do not expose it to heat.

5. Insert the Replacement Battery

1. Align the new battery’s polarity markings with the compartment.
2. Slide the battery into place until it clicks.
3. Snap the clip back onto the battery. A firm connection is essential; the battery should stay in place without wobbling.

6. Reassemble the Doorbell

1. Close the front panel, aligning the seam.
2. Re‑tighten the screw that secures the panel cover.
3. Verify that the panel is flush with the rest of the device.

7. Restore Power and Reset Firmware

1. Plug the power adapter back into the doorbell and wall outlet.
2. Wait for the doorbell to boot. It will automatically reconnect to the Aqara cloud if Wi‑Fi is available.
3. Open the Aqara Home app and navigate to the doorbell’s settings.
4. If the firmware patch is not yet installed, the app will prompt you to update. Follow the on‑screen instructions.
5. Once the update is complete, the doorbell will reboot again.

8. Test the Battery Indicator

The Aqara Home app displays battery status in real time. To verify:

1. Wait for the doorbell to be idle for at least one hour.
2. Check the battery percentage in the app; it should remain stable at a high value (80 %+).
3. If the percentage still fluctuates wildly, proceed to the troubleshooting section.

Troubleshooting Common Issues

Hard Reset Procedure

The Aqara Doorbell 2 does not have a dedicated reset button, but a hard reset can be forced by:

1. Disconnecting power and removing the battery.
2. Holding down the doorbell’s built‑in power button (if available) or the button that triggers the camera for 10 seconds.
3. Re‑inserting the battery, reconnecting power.
4. Letting the device boot fully before applying a firmware update.

Long‑Term Fixes: Replacing the Internal Battery

If the anomaly persists after a battery replacement, the issue may lie in the internal power management IC or the battery contact pad. In such cases, you have two options:

• Professional Repair – Contact Xiaomi or an authorized service center for a diagnostic and battery replacement. They can open the device, clean or replace the internal battery, and test the new unit before returning it to you.
• DIY Soldering – For tech‑savvy users, a replacement 3.7 V Li‑ion cell can be soldered to the internal battery terminal. This requires a hot air rework station and a precision soldering iron. Use a replacement cell with the same voltage and capacity, and be sure to calibrate the firmware’s battery monitoring again.

Preventive Measures

Once your doorbell is repaired, there are several steps you can take to minimise future battery anomalies:

• Regular Battery Checks – Every 3‑4 months, inspect the battery and contacts. Replace the battery if it shows any signs of wear.
• Firmware Updates – Keep the firmware at the latest stable release. Xiaomi’s community forums often discuss issues before they become widespread; stay informed.
• Avoid Over‑Cycling – Let the doorbell sit on mains power; avoid frequent power cycling, which can strain the battery and the power regulator.
• Use a Surge Protector – Protect the power adapter with a surge protector to avoid voltage spikes that could affect the battery regulator.

Frequently Asked Questions

Why did the battery indicator change after the firmware patch?

The firmware introduced a new rolling‑average algorithm for battery sensing. A single low‑voltage sample can skew the average and cause the indicator to drop.

Can I use any 3.7 V Li‑ion battery?

No. The Aqara Doorbell 2 uses a specific cell with a defined capacity and discharge profile. Using a battery with a different chemistry or higher capacity can damage the device.

How long does the replacement battery last?

On average, a fresh 180 mAh battery will last between 6 and 12 months, depending on usage. If you notice rapid depletion, it is likely a firmware or hardware issue.

Is it safe to remove the battery while the doorbell is still plugged in?

It is not recommended. The internal power supply can still deliver a dangerous voltage to the battery contacts. Always unplug the device before touching the battery.

Conclusion

The Xiaomi Aqara Doorbell 2 battery anomaly that surfaced after the latest firmware patch is primarily a software issue, but hardware quirks can amplify the problem. By carefully inspecting the battery, cleaning contacts, and ensuring a proper firmware installation, most users can restore reliable battery reporting and uninterrupted operation. For those encountering persistent issues, professional repair or internal battery replacement is advised. With routine maintenance and updated firmware, your Aqara Doorbell 2 can remain a dependable part of your smart home security suite for years to come.