Does this UPS module charge my backup battery when the main power is on?

No, this 12V Mini UPS Dual Power Switch Module does not have any battery charging or battery protection capabilities. It functions purely as an automatic transfer switch; you must provide your own dedicated battery charger and a BMS (Battery Management System) to keep your backup battery healthy.

Why is the relay making a rapid clicking or chattering noise?

The relay chatters when your input power is insufficient or your wires are too thin, causing a voltage drop when the load activates. When the voltage drops below 10.5V, it switches to the battery, the load is removed from the main power, the main voltage recovers, and it switches back, creating an endless clicking loop. Use thicker wires and a stronger power supply to fix this.

Can I use this module to provide backup power to a 12V DC motor or water pump?

No, you cannot use this module with motors, pumps, or any dynamic loads. Motors create significant voltage fluctuations and inductive spikes during startup and operation, which will confuse the module's voltage detection circuit and cause severe switching instability.

Will this module drain my backup battery while the main power is working normally?

No, this module will not drain your backup battery while the main power is active. The internal relay is driven entirely by the main power supply, meaning the battery circuit remains completely physically disconnected and consumes zero power until a blackout occurs.

Can I get help wiring this UPS module at your store?

Yes, you can bring your DIY UPS project ideas to Sun Cheong Computer Co. Ltd. (新昌電腦有限公司) in Sham Shui Po for expert advice. Our staff can help you map out the IN+, BAK+, and OUT+ solder pads and recommend the correct wire gauges to prevent voltage drop issues.

12V Mini UPS Dual Power Switch Module

Name: 12V Mini UPS Dual Power Switch Module | Auto Transfer
Brand: Sun Cheong Computer Company Limited
SKU: 48039782416535
Price: 19.0 HKD
Availability: InStock

Short Product Description

The 12V Mini UPS Dual Power Switch Module is an ultra-compact (19x16mm) automatic transfer switch designed to keep your critical 12V electronics running during power outages. When the main power drops below 10.5V, this module seamlessly switches your load to a backup battery in ≥10 milliseconds, making it perfect for DIY router UPS setups, CCTV cameras, and access control systems. Available for instant pickup at Sun Cheong Computer Co. Ltd. (新昌電腦有限公司) in Sham Shui Po, where our staff can provide expert wiring advice to ensure your backup power system operates flawlessly.

Key Features

Automatic Power Transfer: Instantly switches to battery backup when the main 12V power supply fails or drops below 10.5V.
Zero Battery Drain on Standby: The relay is powered entirely by the main power supply, meaning it consumes absolutely zero power from your backup battery while the grid is active.
Ultra-Compact Footprint: Measuring just 19x16mm, this tiny PCB can easily be hidden inside existing router enclosures or small junction boxes.
High Current Capacity: Supports a continuous load current of 2A to 3A (with an absolute upper limit of 5A), sufficient for most networking and security hardware.
Wide Battery Compatibility: Supports any battery capacity (Ah), as long as the battery voltage matches what your connected load can safely handle.

Full Product Description

Seamless Power Backup for 12V Devices

This 12V Dual Power Switch Module automatically safeguards your critical electronics by instantly toggling from a main power adapter to a backup battery when a blackout occurs. Operating with a precise detection threshold of 10.5V to 10.6V, the module actively monitors your primary power source; the moment the voltage dips below this level, the onboard Songle relay reroutes the connection to your battery, ensuring your Wi-Fi routers or security cameras stay online.

Lightning-Fast ≥10ms Hardware Switching

The mechanical switching speed of this Mini UPS Relay is rated at an impressive ≥10 milliseconds, ensuring minimal interruption to your connected devices. Please note that the actual real-world transfer time depends on how fast your main power adapter's internal capacitors discharge; the module will execute the switch the moment the adapter's voltage drops to 75-85% of its normal output.

Pro Tip from Our Technicians

To prevent the relay from rapidly clicking or "chattering" between power sources, our Sham Shui Po technical team strongly advises using thick copper wires to minimize voltage drop and ensuring your main power supply has sufficient wattage for your load. Furthermore, this module is strictly a transfer switch—it does not charge your battery or provide low-voltage protection. You must integrate a separate battery charger and BMS (Battery Management System) into your DIY circuit. Lastly, never use this module with motors or dynamic loads, as the inductive spikes will cause severe instability.

Technical Specifications

Product Type: DC UPS Dual Power Switch Module (Automatic Transfer Switch)
Operating Voltage: 12V DC (Input tolerance ±10%)
Detection Threshold: Switches to battery at 10.5V - 10.6V (Temperature drift 0.2V - 0.5V)
Switching Speed: Hardware mechanical speed ≥10ms
Load Current: 2A - 3A continuous (Upper limit 5A)
No-Load Current: 40mA - 60mA (Drawn from main power only)
Relay Type: Songle SRD-12VDC-SL-C
Dimensions: 19mm x 16mm
Supported Loads: Static electronics only (Routers, CCTV, LEDs). Not compatible with motors or dynamic loads.
Charging Function: None (Requires external charger and battery protection circuit)

Delivery Options

Local delivery within Hong Kong and in-store pickup.
Free shipping for orders of HK$400 or above; HK$35 shipping fee for orders below HK$400.
Shipped by SF Express, usually dispatched the same day for orders confirmed before 6:00 PM (Mon–Sat).
Estimated delivery time: 1–3 business days after dispatch (Hong Kong).
In-store pickup details (location and time) will be confirmed by email or phone message.
Delivery times are estimates and may be affected by weather or unforeseen circumstances.

FAQ Section

Does this UPS module charge my backup battery when the main power is on?No, this 12V Mini UPS Dual Power Switch Module does not have any battery charging or battery protection capabilities. It functions purely as an automatic transfer switch; you must provide your own dedicated battery charger and a BMS (Battery Management System) to keep your backup battery healthy.
Why is the relay making a rapid clicking or chattering noise?The relay chatters when your input power is insufficient or your wires are too thin, causing a voltage drop when the load activates. When the voltage drops below 10.5V, it switches to the battery, the load is removed from the main power, the main voltage recovers, and it switches back, creating an endless clicking loop. Use thicker wires and a stronger power supply to fix this.
Can I use this module to provide backup power to a 12V DC motor or water pump?No, you cannot use this module with motors, pumps, or any dynamic loads. Motors create significant voltage fluctuations and inductive spikes during startup and operation, which will confuse the module's voltage detection circuit and cause severe switching instability.
Will this module drain my backup battery while the main power is working normally?No, this module will not drain your backup battery while the main power is active. The internal relay is driven entirely by the main power supply, meaning the battery circuit remains completely physically disconnected and consumes zero power until a blackout occurs.
Can I get help wiring this UPS module at your store?Yes, you can bring your DIY UPS project ideas to Sun Cheong Computer Co. Ltd. (新昌電腦有限公司) in Sham Shui Po for expert advice. Our staff can help you map out the IN+, BAK+, and OUT+ solder pads and recommend the correct wire gauges to prevent voltage drop issues.

Target Users / Applications

Smart Home Enthusiasts: Building custom, hidden battery backups for Wi-Fi routers and smart home hubs to maintain internet access during power cuts.
Security Installers: Creating uninterrupted power supplies for 12V CCTV cameras and electronic access control boards.
Aquarium Keepers: Providing backup power to 12V static LED lighting systems (Note: Not for use with water pumps).

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12V Mini UPS Dual Power Switch Module | Auto Transfer Relay