YX850 Power Failure Automatic Switching Standby Battery Module

The YX850 Power Failure Automatic Switching Module is a compact, low-cost electronic circuit that acts as a mini uninterruptible power supply (UPS). It automatically switches a load to a standby battery when the primary DC power supply fails, and reverts to the primary source when power is restored.Key Specifications

How It Works

• Primary Power Present: The module routes power directly from your primary DC adapter to the load. At the same time, it allows a small trickle current through an onboard diode to charge the standby battery (if a charging voltage is present).
• Primary Power Failure: The mechanical relay clicks over, immediately connecting the standby battery to the load.
• Voltage Matching Rule: The primary DC power supply, the standby battery, and the connected device (load) must all operate at the exact same voltage (e.g., all 12V or all 24V). The module does not step voltage up or down.

Important Technical Considerations

• Switching Delay: Because the module uses a mechanical relay, there is a tiny power gap of 0.7 seconds (700 milliseconds) during the switchover.
• Microcontroller Resets: This 0.7-second delay is long enough to cause sensitive microcontrollers (like an Arduino or ESP8266) to reset. To fix this, you must place a large electrolytic capacitor across the load output to maintain voltage during the brief gap.
• No Charging Regulation: The module features a basic path to charge the battery but does not include charging control or overcharge protection. If using lithium-ion or LiFePO4 batteries, you must use a separate Battery Management System (BMS) board to prevent overcharging or deep discharging.