EF ECOFLOW EFYJ751
EF ECOFLOW DELTA Pro Ultra 6144Wh Power Station User Manual
Model: EFYJ751 | Brand: EF ECOFLOW
1. Introduction
The EF ECOFLOW DELTA Pro Ultra is a high-capacity portable power station designed to provide reliable and expandable power for various applications, including home backup, emergency situations, camping, and RV use. It features a robust 6144Wh LiFePO4 battery, capable of delivering 7200W AC output with 120V and 240V support. This manual provides essential information for the safe and efficient setup, operation, and maintenance of your DELTA Pro Ultra unit.
2. Safety Information
WARNING: Read all safety warnings and instructions before using this product. Failure to follow the warnings and instructions may result in electric shock, fire, and/or serious injury.
- Do not disassemble, repair, or modify the unit.
- Do not place the unit near heat sources or in direct sunlight.
- Do not use the unit in wet environments or immerse it in water.
- Ensure proper ventilation during operation to prevent overheating.
- Handle with care due to the unit's weight (186.4 Pounds). Use appropriate lifting techniques or the included trolley.
- For home integration or complex wiring, consult a qualified electrician.
3. Setup Guide
3.1 Unboxing and Component Identification
Carefully remove all components from the packaging. The standard package includes the DELTA Pro Ultra Inverter and DELTA Pro Ultra Battery. Additional batteries and accessories may be included depending on your purchase.

Figure 3.1: DELTA Pro Ultra showing its modular design and key components.
3.2 Assembly and Stacking
The DELTA Pro Ultra features a modular design allowing for easy stacking of batteries and the inverter unit. The unit comes with a trolley for convenient movement.

Figure 3.2: DELTA Pro Ultra with expandable battery capacity, showing multiple stacked units.
3.3 Initial Charging
Before first use, it is recommended to fully charge your DELTA Pro Ultra unit. The unit can be fully recharged in 2 hours with a single 6kWh battery.

Figure 3.3: Various charging options including Gas Generator, Solar, EV Charging Pile, and AC Wall Outlet.
4. Operating Instructions
4.1 Powering On/Off
Press and hold the main power button on the unit's display panel to power on or off. The display will show battery percentage, input/output wattage, and estimated remaining runtime.
4.2 Output Capabilities
The DELTA Pro Ultra provides a versatile range of power outputs. A single inverter supports 120V & 240V and has an exceptional 7200W AC output, allowing you to run almost any heavy household appliance, including a 3-ton central air conditioner. It features multiple AC outlets, USB-A, USB-C, and DC output ports.

Figure 4.1: Detailed view of the DELTA Pro Ultra's various output ports and their specifications.
4.3 Charging Methods
The DELTA Pro Ultra supports multiple charging methods:
- AC Wall Outlet: Fast charging from a standard wall outlet.
- Solar Panels: Connect compatible solar panels for eco-friendly charging. Supports up to 16.8kW solar input.
- EV Charging Pile: Utilize electric vehicle charging stations for rapid charging.
- Gas Generator: Connect a gas generator for charging during extended outages.
4.4 EcoFlow App Integration
Use the EcoFlow app to monitor and control your DELTA Pro Ultra remotely. The app allows you to prioritize specific circuits in your home, extending your backup even longer, and intelligently analyzes home power usage to offset peak rates.

Figure 4.2: The EcoFlow app provides real-time battery insights, AC always-on control, energy management, and remote control.
4.5 Uninterrupted Power Supply (UPS)
The DELTA Pro Ultra offers Online UPS with 0-ms transfer time, providing 24/7 protection for sensitive electrical devices against power disturbances or grid failure. This ensures your essential appliances remain powered without interruption.

Figure 4.3: The DELTA Pro Ultra seamlessly switches to battery power during grid outages.
5. Maintenance
5.1 Battery Care
The DELTA Pro Ultra uses long-life LiFePO4 batteries. To maximize battery lifespan, avoid extreme temperatures and store the unit in a cool, dry place. Regular partial discharges and recharges are recommended over full cycles.
5.2 Cleaning and Storage
Keep the unit clean and free from dust. Use a dry, soft cloth for cleaning. When storing for extended periods, ensure the battery is charged to approximately 50-60% and recharge every 3-6 months to prevent deep discharge.
6. Troubleshooting
If you encounter issues with your DELTA Pro Ultra, refer to the following common problems and solutions:
- Unit Not Charging: Ensure all cables are securely connected. Check the input source (AC outlet, solar panels, generator) for proper function. Verify the PV switch is in the 'ON' position for solar charging.
- Low Power Output: Confirm the unit is fully charged. Check if the total wattage of connected devices exceeds the unit's output capacity (7200W).
- Unusual Noises/Overheating: Ensure proper ventilation around the unit. The unit is designed for quiet operation (0 dB under 2000W for the first 30 minutes). If unusual noises or excessive heat persist, discontinue use and contact customer support.
- Display Errors: Refer to the EcoFlow app for detailed error codes and troubleshooting steps.
For persistent issues or complex problems, please contact EF ECOFLOW customer support.
7. Specifications
| Feature | Specification |
|---|---|
| Brand | EF ECOFLOW |
| Model Name | EFYJ751 |
| Battery Capacity | 6144Wh (Expandable to 90kWh) |
| AC Output | 7200W (Pure Sine Wave, 120V/240V) |
| Battery Type | LiFePO4 |
| Charging Time (AC) | 2 hours (for 6kWh battery) |
| Max Solar Input | 16.8 Kilowatts |
| UPS Transfer Time | 0-ms (Online UPS) |
| Item Weight | 186.4 Pounds |
| Dimensions (L x W x H) | 27.2"L x 18.9"W x 8.4"H |
8. Warranty
The EF ECOFLOW DELTA Pro Ultra comes with a 5-year manufacturer's warranty. Please retain your proof of purchase for warranty claims. For detailed terms and conditions, refer to the official EF ECOFLOW website or contact customer support.
9. Support
For further assistance, technical support, or service inquiries, please visit the official EF ECOFLOW website or contact their customer support team. You can also utilize the EcoFlow app for troubleshooting guides and direct support.
Video 9.1: Official product overview demonstrating the DELTA Pro Ultra's capabilities as a whole home generator.
Ask a question about this manual
Ask about setup, troubleshooting, compatibility, parts, safety, or missing instructions. Manuals+ will review the question and use this page’s manual context to help answer it.







