1. Important Safety Instructions
Please read and understand all safety instructions before operating the FONOBO Power Inverter. Failure to follow these instructions may result in electric shock, fire, or serious injury.
- Ventilation: Ensure adequate ventilation around the inverter. Do not cover ventilation openings.
- Dry Environment: Do not expose the inverter to water, rain, or spray. Operate in a dry environment.
- Proper Connection: Connect the inverter only to a 12V DC power source. Incorrect voltage can damage the unit and connected devices.
- Polarity: Always observe correct polarity when connecting to the battery (Red to Positive, Black to Negative). Reverse polarity will trigger protection and may cause damage.
- Load Capacity: Do not exceed the rated continuous power of 300W/500W (depending on model) or the peak power of 4000W/6000W. Ensure the total rated power of connected devices is ≤ 300W/500W.
- Children: Keep the inverter out of reach of children.
- Heat: The inverter generates heat during operation. Avoid placing it near flammable materials.
- Internal Fuses: The inverter has internal fuses for protection. Do not attempt to replace them yourself.
2. Product Overview
The FONOBO Power Inverter converts 12V DC power from your vehicle battery into 220V AC household power, making it suitable for various applications such as camping, outdoor activities, and emergency power supply. It features dual USB ports for charging mobile devices and multiple safety protection functions.
Key Features:
- Modified Sine Wave Output
- LED Battery Display for capacity monitoring
- Dual USB Ports for fast charging
- Multiple Safety Protections: Reverse polarity, low/high input voltage, over-current, short circuit, over-temperature, overload.
- Intelligent Cooling Fan
- Compact and Lightweight Design
Components:

Figure 2.1: Front and Rear View of the FONOBO Power Inverter with labeled components.
- Plastic Shell: Durable outer casing.
- Universal Socket: For connecting 220V AC devices.
- On/Off Switch: Controls the power to the inverter.
- Dual USB Ports: For charging USB-powered devices.
- Red Fault Light: Indicates an error or protection mode.
- Green Work Light: Indicates normal operation.
- Battery Capacity Display: LED display showing battery charge level.
- Cooling Fan: Activates to dissipate heat during operation.
- (+) Positive DC Terminals: Red terminal for positive battery connection.
- (-) Negative DC Terminals: Black terminal for negative battery connection.
3. Setup and Installation
Proper installation is crucial for safe and efficient operation of your power inverter.
Connecting to a 12V DC Power Source:
The inverter can be connected to a 12V DC power source using either the included battery clips or the cigarette lighter plug.

Figure 3.1: FONOBO Power Inverter with connection accessories.
- Battery Clip Connection (Recommended for higher power loads):
- Ensure the inverter's power switch is in the 'OFF' position.
- Connect the red battery clip cable to the (+) Positive DC Terminal on the inverter and the positive terminal of your 12V battery.
- Connect the black battery clip cable to the (-) Negative DC Terminal on the inverter and the negative terminal of your 12V battery.
- Ensure all connections are tight and secure.
- Cigarette Lighter Plug Connection (For lower power loads, typically up to 150W):
- Ensure the inverter's power switch is in the 'OFF' position.
- Plug the cigarette lighter cable into the DC input port of the inverter.
- Insert the cigarette lighter plug into your vehicle's 12V cigarette lighter socket.
Example Connection Diagram (Solar System):

Figure 3.2: Example of a solar system connection using the FONOBO Power Inverter.
4. Operating Instructions
Follow these steps to operate your FONOBO Power Inverter safely and effectively.
- Connect the Inverter: Ensure the inverter is properly connected to a 12V DC power source as described in Section 3.
- Turn On the Inverter: Flip the On/Off switch on the inverter to the 'ON' position. The green 'Work Light' should illuminate, indicating normal operation. The LED Battery Display will show the current battery capacity.
- Connect AC Devices: Plug your 220V AC devices into the universal AC socket on the inverter. Ensure the total power consumption of all connected devices does not exceed the inverter's rated continuous power.
- Connect USB Devices: Plug your USB-powered devices into the dual USB ports for charging.
- Monitor Battery Level: The LED Battery Display has five levels (lattices), each representing 20% of the battery power. When the battery is low, the display will flash to remind you to charge your battery.
- Turn Off the Inverter: When you are finished using the inverter, first disconnect all AC and USB devices, then flip the On/Off switch to the 'OFF' position. Finally, disconnect the inverter from the 12V DC power source.
Typical Usage Scenarios:

Figure 4.1: The FONOBO Power Inverter can be used in various settings such as for medical devices (CPAP), marine applications (yacht), recreational activities (camping), and vehicle power (truck).

Figure 4.2: The inverter provides power for both indoor and outdoor applications, such as powering laptops or lights during camping.
5. Maintenance
Regular maintenance ensures the longevity and optimal performance of your FONOBO Power Inverter.
- Cleaning: Periodically clean the exterior of the inverter with a dry, soft cloth. Do not use liquid cleaners or solvents.
- Ventilation: Ensure the cooling fan and ventilation openings are free from dust and debris. Blocked vents can lead to overheating.
- Connections: Regularly check all electrical connections (battery clips, cables) to ensure they are secure and free from corrosion.
- Storage: When not in use for extended periods, store the inverter in a cool, dry place, away from direct sunlight and moisture.
6. Troubleshooting
This section addresses common issues you might encounter with your power inverter.
| Problem | Possible Cause | Solution |
|---|---|---|
| No output power / Inverter not turning on | Inverter switch is OFF Loose battery connection Low input voltage (battery discharged) High input voltage Reverse polarity | Turn switch ON Check and secure connections Recharge or replace battery Verify 12V DC input Correct battery polarity |
| Red Fault Light is ON | Overload protection Over-temperature protection Short circuit protection Low/High input voltage | Reduce connected load Allow inverter to cool, ensure ventilation Check for short circuits in connected devices/cables Check battery voltage |
| Inverter shuts down unexpectedly | Overload Overheating Low battery voltage Short circuit | Reduce load Ensure proper ventilation Recharge battery Inspect connections and devices |
| LED Battery Display flashing | Battery is low | Recharge the 12V battery |
If the problem persists after attempting these solutions, please contact FONOBO customer support.
7. Specifications
Detailed technical specifications for the FONOBO 4000W Power Inverter.

Figure 7.1: Physical dimensions of the FONOBO Power Inverter and its cables.
| Feature | Specification |
|---|---|
| Model | Inverter |
| Input Voltage | DC 10.5V - 15V |
| Output Voltage | AC 220V |
| Output Frequency | 50Hz |
| Peaks Power | 4000W |
| Rated Power | 300W |
| Output Waveform | Modified Sine Wave |
| Unit Count | 1.0 Count |
| Dimensions (Inverter) | Approx. 20.5cm (8.1in) L x 11.7cm (4.6in) W x 5.8cm (2.3in) H |
| Cigarette Lighter Plug Cable Length | Approx. 42.5cm (16.7in) |
| Battery Clip Cable Length | Approx. 46.8cm (18.4in) |
8. Warranty and Support
FONOBO is committed to customer satisfaction. If you encounter any issues or have questions regarding your power inverter, please do not hesitate to contact our support team.
- Customer Service: For assistance, please contact us via Amazon email or through our official website. Our support team is available 24/7 to assist you.
- Warranty: Specific warranty details may vary. Please refer to your purchase documentation or contact customer support for warranty information.