Frequently Asked Questions (FAQ)

Q: How long does the battery last? 

A: Battery life varies depending on user usage scenarios. Theoretically, under standard usage conditions of unlocking 10 times per day, the battery can last approximately four months. Actual usage time may be affected by factors such as unlocking frequency, ambient temperature, and the status of enabled features.

Q: How do I know when the battery needs charging? 

A: When the battery voltage drops to a preset threshold, the lock will proactively send a low battery notification to the user's mobile app. It is recommended that users charge the lock promptly after receiving the notification to avoid functional issues due to complete battery depletion.

Q: Can the lock's battery be charged via the Micro USB port? 

A: No. The Micro USB port on the lock is solely for connecting an external power source for direct power supply (e.g., for emergency power or to quickly wake the device). It does not support charging the internal battery. Charging must be done using the provided charging dock or an officially specified charging method.

Q: Under what circumstances is the backup battery activated?

A: When the main battery (15,000mAh lithium battery) is depleted or removed, the backup battery will automatically activate, ensuring the lock continues to operate in a low-power mode. Once the backup battery is active, it is recommended to immediately recharge the main battery or use the Micro USB port for emergency access. This prevents the backup battery from draining rapidly, which might lead the lock to completely lose power.

Q: Which functions are limited when using the backup battery?

A: When powered by the backup battery, the following functions will be disabled to extend its operational time:

• Palm Vein Unlocking: Disabled due to the high power consumption required for the recognition process.

• Camera: The backup battery cannot support the continuous operation of video functions.

Core functions that remain active:

• Wi-Fi Connection: Users can still remotely check the lock status and perform lock/unlock operations via the eufy app.

• Emergency Unlocking: The physical key or the emergency power port can still be used normally.

Other Issues and Solutions

Inaccurate Battery Level Display

Reason:

• When the lock motor operates at high power (e.g., during frequent unlocking or due to a mechanical fault), it can cause a sharp drop in the battery voltage, potentially affecting the accuracy of the battery level calculation.

Response: 

• Explanation of Normal Phenomenon: Battery level detection has inherent precision limits. Combined with high power consumption from the motor, occasional inaccuracies can be a normal physical phenomenon and do not necessarily indicate a device malfunction.

• Recommended Action: If the displayed battery level significantly differs from expected usage, rely on the low battery notifications sent to the app, or consider periodically replacing/recharging the battery to ensure stable device operation.

Reduced Battery Life in Low Temperatures

Reason:

• In low-temperature environments below 0°C (32°F), the chemical reaction rate within batteries decreases. This leads to significantly reduced discharge performance and consequently shortens the battery's operational time.

Response: 

• Recommended Battery Type (if applicable): If using replaceable batteries (like AA/AAA often used as backups or in different models), use alkaline zinc-manganese dry cell batteries. These generally perform better in low temperatures compared to carbon-zinc or other types of dry cell batteries, helping to mitigate the reduced life issue. 

• Environmental Recommendation: Avoid exposing the lock to extremely low temperatures for extended periods. If necessary, consider insulation measures or ensure timely battery recharging/replacement.

Long Charging Time

Reason:

• The high capacity of the main battery (15,000mAh lithium battery), while providing extended usage, naturally requires a longer charging time compared to batteries with a smaller capacity. Furthermore, the product utilizes a standard 5V/2A charging rate. This is an intended design; using a lower current helps to extend the overall lifespan of the battery by avoiding the potential long-term negative effects that fast charging technologies can have on battery health.

Response: 

• Overnight Charging (Recommended): When using the official 5V/2A charger, a full charge typically takes approximately eight hours. It is recommended to charge the battery overnight so it is fully charged by morning.

• Quick Swap with Spare Battery: To minimize downtime during charging, consider purchasing an official spare main battery. By keeping a spare battery charged in advance, you can quickly swap it when the primary one needs to be recharged, ensuring continuous lock operation and maintaining security features.

Precautions

Battery Replacement and Charging: 

• For the main battery, it is strongly recommended to use only officially certified lithium batteries to guarantee compatibility and safety.

• If replacing any dry cell batteries (e.g., backup batteries if applicable), choose high-quality alkaline batteries of the correct model, especially when operating in low-temperature environments.

Function Optimization: 

• Minimize unnecessary high-power operations (such as frequently using the camera to capture unlock records) to help extend the main battery life.

• When the backup battery is activated, prioritize using the physical key for emergency access to conserve the backup power.

If you have any other questions about the FamilLock S3 Max, please don't hesitate to contact eufy Support Engineers for further assistance.