The YX850 (JY-850) Power Failure Automatic Switching Module is a critical safety component for any DC-powered system that cannot afford downtime. At Electrapac, we recommend this module for users building DIY UPS systems for routers, security cameras, or medical monitoring equipment where a seamless transition to battery power is essential during a blackout.

Product Overview

The YX850 is an intelligent Automatic Transfer Switch (ATS) designed for DC systems ranging from 5V to 48V. It functions by prioritizing your main DC power adapter. When the grid is active, the module powers your device and simultaneously trickles power to your backup battery. The moment the primary DC power fails, the module’s onboard relay snaps over to the battery source in milliseconds, keeping your equipment running.

Key Features for Electrapac Customers

• Universal Voltage Compatibility: Whether you are running a 5V Raspberry Pi, a 12V router, or a 24V industrial sensor, this one module handles it all.

• Bi-directional Charging: When the main power is restored, the module doesn't just switch back—it also allows the main DC source to recharge the standby battery.

• High Current Handling: With a 10A rating, it can handle significant loads (up to 120W at 12V or 480W at 48V).

• Plug-and-Play Simplicity: No complex programming or external microcontrollers required. It is a hardware-level solution for immediate reliability.

• Fail-Safe Design: Uses a high-quality mechanical relay to ensure a physical physical connection, providing better isolation than some purely electronic switches.

Wiring & Terminal Guide

To set up your Electrapac emergency power system, follow these terminal markings:

1. DC+ / DC-: Connect your primary power adapter here (your wall-plug adapter).

2. BAT+ / BAT-: Connect your backup battery here (Lithium-ion, Lead-Acid, etc.).

   • Important: The battery voltage must match your DC adapter voltage.

3. OUT+ / OUT-: Connect your device (the Load) here.

⚠️ Pro-Tip from Electrapac: This module does not regulate charging voltage. Your primary DC power supply should be the correct voltage for your specific battery type (use a 12.6V adapter if you are using a 3S Lithium battery pack).

Primary Applications

• DIY Router UPS: Keep your internet online during power cuts by connecting a 12V battery as backup.

• Security Systems: Ensures CCTV cameras and DVRs continue recording even if an intruder cuts the power.

• Access Control: Powering electronic door locks and RFID readers.

• Incubators & Fish Tanks: Maintaining critical temperature or oxygen levels during emergencies.

• Smart Home Hubs: Preventing Home Assistant or Zigbee gateways from rebooting during voltage fluctuations.

Why Shop at Electrapac?

We rigorously check our YX850 modules to ensure the relay contacts are rated for the full $10\text{A}$ load without sticking. Visit us at for the reliable switching modules that ensure your projects never go dark.