RHUNDO RS-21S 3-way Car Power Splitter & Dual USB 3.4A — Remote Touch Sensor, Battery Protection

Compact but feature-rich, the RS-21S converts a single vehicle 12V socket into three cigarette lighter outputs plus two USB ports (3.4A combined), while a detachable touch sensor panel displays voltage, USB amps, timer and optional temperature. Built-in protections include low-voltage cut-off, overload protection and automatic power-off timers, making it a practical upgrade for drivers who run multiple accessories at once.

How does the RS-21S keep my car battery safe?

The adapter includes a Battery Discharge Prevention (BDP) system that cuts power when voltage drops below a set threshold and prevents excessive drain. You can set the low-voltage cut-off within the 11.0V–14.0V range and use the start-up delay and automatic power-off timer to limit accessory run time.

• Adjustable low-voltage cut-off (11.0V–14.0V)
• Start-up delay timer (1–30 seconds) prevents inrush surges
• Automatic power-off timer (1–120 minutes) for scheduled shutdown
• Overload protection to prevent circuit damage

What information does the touch sensor LED panel show?

The detachable remote touch sensor panel displays four types of data: vehicle battery voltage, real-time USB output amperage, an active timer countdown, and optional temperature when a sensor is connected. Brightness is adjustable across nine levels so it’s readable day or night without distracting the driver.

• Voltage readout for quick battery checks
• USB amp meter to monitor charging load
• Timer display for automatic shutoff tracking
• Optional temperature display with add-on sensor

How do the touch switches and memory features improve usability?

Four touch-sensor switches control the three lighter sockets and the USB outputs independently, plus a master power switch for the whole unit. Both the individual switches and the master switch remember their last ON/OFF state after power loss, so your preferred setup is restored automatically.

• Three switches for individual lighter socket control
• One switch for both USB ports together
• Master power switch to cut all outputs instantly
• Power status memory restores previous settings after restart

What power and build details matter when installing?

The RS-21S supplies two USB ports with a combined 3.4A output—suitable for charging phones, tablets and compact devices—and three standard cigarette lighter sockets for accessories like dash cams, GPS units or portable fridges. The unit is designed in Korea and built for automotive compatibility, with a start-up delay and robust safety circuitry for reliable in-vehicle use.

• Dual USB ports, combined 3.4A output for fast charging
• Three cigarette lighter sockets for multiple accessories
• Start-up delay reduces electrical surge on ignition
• Designed by STYLISHWIZ, branded RHUNDO for premium fit and finish

Who is this for? The RHUNDO RS-21S is aimed at drivers who use several powered accessories simultaneously—road travelers, rideshare drivers, overlanders and anyone who wants a smarter, safer way to expand a single 12V outlet. It’s useful when you need to monitor charging loads, protect your battery, and switch multiple devices independently without cluttering the dashboard.