Using an SMPS to Avoid Pass Through Mode

Background

I started my EcoFlow journey back in September 2021 when I wanted to power my 5th wheel camper without running a noisy generator. The DELTA Pro kickstarter was perfect so I purchased a DELTA Pro, a 400w portable solar panel, and the EcoFlow solar tracker. Then realized that I could also use this to power my home in emergencies and potentially offset my electrical costs. In order to run my 240 volt well pump, I would need a second DELTA Pro. Since the EcoFlow Smart Home panel was not available in Canada, I was forced to go down the path of adding an EcoFlow Double Voltage Hub. I also needed more capacity to power my entire home for any length of time, so I added four EcoFlow DELTA Pro Smart Extra Batteries to max it out. It was the complexities of being able to AC charge DELTA Pros connected to a Double Voltage Hub while fully powering home circuits and avoiding pass-through mode that lead me down the path of adding a Switched Mode Power Supply (SMPS) to my system.

What is Pass-Through Mode?

When connected to solar panels or when completely standalone, the EcoFlow DELTA Pro can supply up to 3,600 watts of power through its 20a and 30a AC outlets. As soon as you plug a DELTA Pro into a 120v AC outlet, the DELTA Pro knows that North American outlets are limited to 15 amps and it will switch to pass-through mode. In pass through mode, the DELTA Pro will be limited to 1,800 watts instead of the usual 3,600 watts of power. Also, the DELTA Pro will attempt to charge its batteries and extra batteries based on the charge level set in the EcoFlow app. Since the DP has a max charge rate of 1,800 watts when it being charged from 120 volts AC, this means if you have 1,000 watts of loads, only 800 watts would be going to the DELTA Pro charging. Consequently, the combination of charge rate plus loads must NEVER exceed 1,800 watts or the DP will overload and shut off the AC output.

Switched Mode Power Supply

A switched mode power supply quite simply takes takes AC current and outputs DC current. A fuller description can be found in this Wikipedia article.

Reasons for using an SMPS:

1. Avoids pass-through mode limiting the DELTA Pro's AC output to 1,800w in order to get the full 3,600w of output while charging via 120v AC
2. Enables use of a non-inverter type generator which does not output pure sine wave alternating current to charge an EcoFlow solar generator via the solar inputs
3. Electrically isolates a Manual Transfer Switch (MTS) to avoid dangerous ground loops while AC charging from a household outlet

I am using a pair of Ideal Plusing 2000w SMPSes which I ordered from Alibaba and had to wait while they took a slow boat from China. This company makes several sizes so if you are trying to power a smaller RIVER or DELTA portable power station, be sure to look at the solar input specs and select a suitable SMPS. An SMPS electrically isolates my DELTA Pros by converting 120v AC to DC and feeding DC into my solar inputs. This eliminates the potential for a ground loop, does not cause the DELTA Pros to go into pass-through mode, and it doesn't matter whether the SMPSes are plugged into the same phase or opposite phases of my 120v split phase breaker panel.

To wire this up, connect the 120v or 240v AC input wires to the N, L, and ground and connect the solar wires to V- and V+ making sure to get the polarity right. Before plugging into a solar generator, make sure to measure the voltage with a multimeter and adjust using by turning the small screws between the input and output terminals.

Here is a demonstration with a 1,200 watt SMPS (an older model before I switch to Ideal Plusing) powering my DELTA Pros

Using an SMPS with a Generator

I have a Yamaha EF 6300iSDE inverter generator which I purchased before I bought my DELTA Pros. Although my Yamaha EF 6300iSDE is an inverter generator which produces pure sine wave power, many open frame or older generators do not output a pure sine wave. So if using a generator which does NOT produce pure sine wave power, the DELTA Pros will not recognize the "dirty" power from such generators.

However, by connecting two SMPSes to generator capable of outputting 240v that does not produce pure sine wave power, using a number of adapters, the SMPSes convert this "dirty" power to clean DC power allowing users to charge their DELTA Pros through their solar inputs. If using the 2000 watt version of the SMPS, a 120v generator would need to be capable of outputting a sustained 1875 watts for each SMPS."

Using an SMPS with a Manual Transfer Switch to avoid dangerous ground loops

Using a SMPS is the only way other than using TWO EcoFlow Smart Generators or using solar panels for the DP's to have their batteries charged WHILE connected to Double Voltage Hub which is supplying 240 volts to a MTS. If you plug DELTA Pros into outlets while also feeding a manual transfer switch, this creates all sorts of problems with ground loops, potentially having both DPs on the same phase, pass-through mode limiting your output, and possibly lighting your house on fire. See Mark Hicks' article Powering Home Circuits for more information about this.

My entire setup

Here is my EcoFlow setup which includes:

• Two DELTA Pros with four DELTA Pro Smart Extra Batteries
• Two SMPSes feeding the DELTA Pro solar inputs
• A Double Voltage Hub
• Two Smart Generators (purchased after the Yamaha generator)
• A Victron Autotransformer
• Other EcoFlow devices not related to my whole house system (RIVER, RIVER Pro, DELTA 2, DELTA 2 Max, WAVE, WAVE 2)

Here is a rear view

On the wall next to the shelf you can see my 240v AC power inlet as well as some DC switches which I added to be able to switch to solar panel charging during the day and SMPS charging at night.

Using an SMPS with the new Delta Pro ULTRA

If you own a DELTA Pro Ultra, the low-voltage PV input port has simlar 1600w/150v/15a specs as the DELTA Pro. So DPU users can add the same SMPS I use to charge a DPU from a generator or plug into a 120v AC outlet and circumventing ground loop issues (discussed above) while connected to a manual transfer switch