Introduction
This manual provides essential information for the safe and efficient operation, installation, and maintenance of your WFCO WF9875 Deck Mount 75 Amps Converter Charger. This unit is designed to provide clean, reliable DC power for your recreational vehicle (RV) or other compatible applications, while also featuring an advanced 3-stage battery charging system.
Please read this manual thoroughly before installation and use to ensure proper function and to prevent damage to the unit or connected systems.
Safety Information
Always observe the following safety precautions to reduce the risk of electric shock, fire, or injury.
- Electrical Hazard: Ensure all power sources are disconnected before installing or servicing the converter charger. Failure to do so can result in severe injury or death.
- Ventilation: Install the unit in a well-ventilated area. Do not block ventilation openings. Overheating can cause damage to the unit and pose a fire hazard.
- Battery Safety: Batteries can produce explosive gases. Work in a well-ventilated area and avoid open flames or sparks near batteries. Wear eye protection.
- Proper Wiring: All wiring must comply with local and national electrical codes. Use appropriate wire gauges for all connections.
- Moisture: Do not expose the converter charger to rain, moisture, or excessive humidity.
- Qualified Personnel: Installation and servicing should be performed by qualified personnel familiar with electrical systems and RV components.
Product Overview
The WFCO WF9875 is a robust power converter designed for reliable performance in various applications, particularly recreational vehicles. It converts 120 VAC shore power into 12 VDC power for your RV's lights and appliances, and simultaneously charges your house battery.

Figure 1: WFCO WF9875 Deck Mount 75 Amps Converter Charger. This image shows the grey metal casing of the converter, with ventilation grilles on the sides. The input power cord is visible on the left, and the DC output terminals (red and black) are on the right, along with fuse holders. Labels with caution and warning information are visible on the top surface.
Key features include:
- Clean DC Power: Provides stable 12 VDC power for sensitive electronics.
- Advanced 3-Stage Charger: Automatically switches between bulk, absorption, and float modes to optimize battery charging and extend battery life.
- Deck Mount Design: Designed for easy installation on a flat surface.
Setup and Installation
Proper installation is crucial for the safe and efficient operation of your converter charger. If you are not comfortable with electrical wiring, consult a qualified electrician or RV technician.
Pre-Installation Checklist:
- Ensure all AC and DC power is disconnected from the RV or system.
- Verify the mounting location is dry, well-ventilated, and can support the unit's weight (approximately 6.75 pounds).
- Confirm adequate space for wiring connections and air circulation around the unit.
- Gather necessary tools: screwdrivers, wire strippers, crimpers, voltmeter, appropriate wire connectors, and mounting hardware.
Mounting Instructions:
- Position the converter charger on a flat, stable surface. The unit is designed for deck mounting.
- Ensure there is at least 1 inch of clearance around all ventilation openings for proper airflow.
- Secure the unit using appropriate screws through the mounting tabs.
Wiring Connections:
AC Input (120 VAC):
- Connect the AC input wires from your RV's main AC distribution panel to the converter's AC input terminals. Ensure proper polarity (Line, Neutral, Ground).
- The unit typically requires a dedicated 20-amp circuit breaker.
DC Output (12 VDC):
- Connect the positive (+) DC output terminal (red) to your RV's 12V distribution panel or directly to the positive terminal of your house battery.
- Connect the negative (-) DC output terminal (black) to the common negative bus bar or the negative terminal of your house battery.
- Ensure all DC connections are tight and secure. Use appropriate fuse protection on the DC output circuit as required by code.
After all connections are made, double-check all wiring for correctness and security before restoring power.
Operating Instructions
The WFCO WF9875 operates automatically once properly installed and connected to an AC power source and a battery.
Automatic 3-Stage Charging:
The converter charger features an intelligent 3-stage charging system to ensure optimal battery health and longevity:
- Bulk Mode (14.4 VDC): When the battery voltage is below 13.6 VDC, the converter delivers maximum current to rapidly recharge the battery.
- Absorption Mode (13.6 VDC): Once the battery reaches 14.4 VDC, the converter automatically drops the voltage to 13.6 VDC. This stage safely completes the charge and prevents overcharging.
- Float Mode (13.2 VDC): After approximately 44 hours in absorption mode, or if the battery is fully charged, the converter enters float mode, maintaining a safe 13.2 VDC to keep the battery topped off without overcharging.
The converter will automatically switch between these modes based on the battery's charge state and the DC load demand.
Powering On/Off:
To operate the unit, simply connect it to a live 120 VAC power source. The converter will automatically begin providing 12 VDC power and charging the battery. To turn off, disconnect the 120 VAC input power.
Maintenance
Regular maintenance helps ensure the longevity and optimal performance of your WFCO converter charger.
- Cleaning: Periodically clean the exterior of the unit with a dry cloth. Ensure ventilation openings are free from dust and debris. Do not use liquid cleaners.
- Fan Operation: The internal cooling fan will operate as needed to maintain optimal temperature. Ensure the fan is not obstructed and can draw in cool air and expel warm air.
- Connections: Annually check all AC and DC wiring connections for tightness and corrosion. Loose connections can cause overheating and poor performance.
- Fuses: The unit may contain internal fuses. If the unit stops providing power, check the fuses. Always replace fuses with the same type and rating. Refer to the unit's labeling for fuse specifications.
- Battery Health: Regularly check the water levels (if applicable) and terminal cleanliness of your RV batteries. A healthy battery contributes to the efficient operation of the converter charger.
Troubleshooting
If you experience issues with your WFCO WF9875, refer to the following common problems and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| No 12VDC output / No battery charging |
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| Converter fan runs constantly or loudly |
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| Battery not fully charging |
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If the problem persists after attempting these solutions, contact WFCO customer support or a qualified technician.
Specifications
| Attribute | Value |
|---|---|
| Model | WF9875 |
| Brand | WFCO |
| Manufacturer | Arterra |
| Output Amperage | 75 Amps |
| Wattage | 90 watts |
| Input Voltage | 120 VAC |
| Output Voltage | 12 VDC (Nominal) |
| Charging Stages | 3-Stage (Bulk, Absorption, Float) |
| Item Weight | 6.75 pounds |
| Product Dimensions (L x W x H) | 12 x 6.25 x 4 inches |
| Recommended Uses | Car, Truck, Van, Recreational Vehicle |
| Power Source | Battery Powered (for DC output) |
Warranty and Support
WFCO products are designed for reliability and performance. For specific warranty information, please refer to the warranty card included with your product or visit the official WFCO website. Keep your purchase receipt as proof of purchase for warranty claims.
For technical support, troubleshooting assistance, or to inquire about replacement parts, please contact WFCO customer service directly. Contact information can typically be found on the manufacturer's website or on the product packaging.





