DC Voltage Display Relay Controller 6 to 80V Monitor

Introducing the DC Voltage Display Relay Controller A30-U3 / A30, a compact and reliable voltage monitor with a built-in relay output designed for power systems, battery protection, and general voltage control. Powered from DC 6–80V, it provides a clear digital voltage readout and automatic relay switching when the monitored voltage crosses your set thresholds. The A30 model features intuitive two-button operation with a protective cover, while the A30-U3 adds advanced timing modes for flexible control in demanding applications. This CE-certified module is ideal for battery protection, charging/discharging control, and voltage detection tasks across a wide range of DIY and professional projects.

Main Description

The device continuously monitors DC voltage and displays the value on a bright LED readout for quick, at-a-glance checks. It supports a broad detection range (0–99.9V) with high precision (±0.1V) and steplessly adjustable limits to trigger the relay output. With NO/NC contact options, you can configure the module to cut off or enable loads based on voltage conditions, helping protect batteries and power circuits from overvoltage or undervoltage scenarios. A protective cover shields the electronics in busy environments, and the A30 variant adds convenient manual controls, while the A30-U3 offers programmable timing modes for more complex automation needs.

Both variants are designed for durability and reliability in real-world use. They are suitable for voltage monitoring, charging/discharging control, overvoltage/undervoltage protection, and as a versatile voltage-detection switch in a wide array of applications. The module is origin Mainland China and CE-certified, underscoring its quality and compliance.

Note: For high voltage DC applications, contacts are susceptible to arcing. When using DC loads above 60V, keep the load current under 10A to preserve contact life and performance.

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Benefits & Tips

• Voltage-based protection: Set lower and upper voltage thresholds to automatically disconnect loads or trigger alerts, protecting batteries and power supplies from damage due to under- or over-voltage.
• Flexible timing (A30-U3): Utilize on-delay and off-delay modes with a timer range of 0–999 seconds to create precise voltage-control sequences for charging, discharging, or sequencing loads.
• Easy setup and monitoring: The digital display provides immediate voltage feedback, while NO/NC outputs let you tailor the relay behavior to your circuit needs. Use the protective cover for added durability in demanding environments.

Product Specifications

• Voltage range: DC 6–80V (power supply)
• Voltage detection range: DC 0–99.9V, accuracy ±0.1V
• Quiescent current: 8mA/24V (relay open, LED off ~4mA/24V); 58mA/24V (relay closed)
• Contact configuration: NO and NC (convertible); NO: 30A/250V AC or 30A/30V DC; NC: 20A/250V AC or 20A/30V DC
• Load considerations: High DC voltages can cause arcs; load above DC60V should be kept under 10A for reliability
• Contact resistance: ≤100mΩ (1A, 6VDC)
• Mechanical durability: 10 million cycles
• Electrical durability: >100,000 cycles (as rated)
• Operating temperature: -40°C to 85°C
• Form factor: Item size 9.4 × 5.2 × 3 cm (3.7 × 2.05 × 1.18 in); Package size 9.5 × 6 × 3 cm (3.74 × 2.36 × 1.18 in); Package weight around 85 g
• A30-U3 additional features: On-delay/off-delay timing; timer range 0–999 seconds; detection sampling delay 0.1–0.9 seconds; four operating modes (P-1 to P-4); minimum display-off current 4 mA at 24V; settings auto-save after power off
• Material: ABS housing (A30-U3/A30)

Package includes:

• 1 x DC Voltage Display Relay Controller (A30-U3 / A30)
• Protective cover

Warnings/Reminders

• High voltage DC arcing can damage relay contacts. For DC loads above 60V, keep current below 10A to extend life.
• Voltage detection range 0–99.9V with ±0.1V accuracy; ensure proper wiring to avoid incorrect readings.
• When the display is off (A30-U3 mode), the minimum current is 4 mA at 24V (relay open).
• This device is intended for general-purpose voltage control and protection; follow all applicable electrical safety standards during installation.