EcoFlow Delta 2 powerstation review: Flexible and advanced, but loud

EcoFlow has been a trusted brand in power station manufacturing for over a decade. But, there is one problem: the battery chemistry. EcoFlow’s Delta 2 addresses this issue by switching to lithium ironphosphate cells. This triples the battery’s duty cycle.

That’s likely to ease the minds of consumers who expect to heavily use their power stations.

Note: This review is part of our ongoing roundup of the best portable power stations. Visit the site to learn about rival products, what to search for in a power source, and to get buying advice.

EcoFlow Delta 2: The difference between lithium iron and phosphate

To be honest, it is possible to overstate the arguments about battery chemistry. With the original 1,000WHr Delta, for example, it would take 800 full discharge cycles before the battery’s capacity would drop to 80 percent. That’s similar to what you would see in a laptop or phone, which you would actually charge and discharge daily or every other day.

But most people are unlikely to give a portable power station that kind of a workout unless you’re permanently off the grid. Realistically, it’ll sit around until it’s used for a camping trip or occasional power outages.

Many people find it very appealing to go from 800 charge cycles to 3,000 with the lithium ironphosphate chemistry. With so many charge cycles, you might even consider keeping it plugged-in full time to be an ad-hoc UPS.

This would work with a laptop, but not a computer. That’s because the Delta 2 takes 30 milliseconds to take over once power has been cut. A PSU can run 16ms on most desktops that conform to the ATX specification before power is lost. The Delta 2 is much faster than the 30ms, which means that most desktop PCs will not reboot immediately after power is lost.

This doesn’t impact laptops, which have a battery to rely on while power is switched over. Similarly, fans, refrigerators, and most other household equipment doesn’t mind losing power for a fraction of a second. There’s no concern about losing data.

EcoFlow Delta 2: Design & ports

The Delta 2 doesn’t change much externally from the original model, with handles on both ends that are strong enough to lug around the 27 pound power station one-handed if you need to. EcoFlow has moved both the AC and solar charging ports to the back of Delta 2. The connector used to connect to the solar ports is the XT60 connector. If you go this route, pay careful attention that the voltage of your solar panels remains below the Delta 2’s limit of 500 watts. For extra assurance, opt for an EcoFlow-branded setup.

We tested the Delta 2 with the company’s 220-watt bifacial panels and could push 140 watts to 150 watts from a low-angle fall sun. That was enough to offset our refrigerator’s power consumption of 172 watts, and yes, you can charge the Delta 2 while using it.

Gordon Mah Ung

Charging over solar is great, but cloudy days can make charging very tedious and nerve wracking if you’re worried you won’t have time to recharge before the sun sets. If you’re in a pinch during a power outage and can’t wait hours and hours to charge the station via solar panel, the Delta 2 has impressive AC charge rates if you can get it to a working outlet.

The Delta 2 can be plugged into AC and charged at up 1,200 watts. This allows it to go from 0 to 100 percent in approximately an hour 20 minutes. The Delta 2’s aggressive charge input doesn’t run at 1,200 watts the entire time—like most laptops and phones, it eases back as it approaches full power to preserve battery longevity.

You can also use the XT60 port for DC charging in your vehicle (the cable is included). You also get a cigarette car lighter and two 5.5mm “barrel” ports. The cigarette charger is rated at 12.6V/10A, or 128Watts. The two barrel charger ports, which can each reach 38W at 12.6V, can be used to charge up to 38Watts. It is okay to use 12.6 volts as a car charger, but some devices may need the full 13.6-14 volts that a typical car alternator provides for their operation. If your device needs that much voltage, the Delta 2’s DC-out may not work for it.

Gordon Mah Ung

The Delta’s front features four USB-A ports, and two USB-C ports. The USB-C ports were tested and reported that they can charge USB 3.0 Power Delivery at five volts to nine volts to twelve volts to 15 volts to 20 volts at 5 volts. Both ports can charge a USB C laptop at up 100 watts.

Two of the USB-A ports are the standard 5 watt, while the two blue ports on the right support more advanced charging rates using QuickCharge 2.0 and 3.0 up to 12 volts, as well as Samsung’s AFC up to 9 volts, and Huawei’s FCP up to 9 volts or 18 watts.

Gordon Mah Ung

The Delta 2’s backside has six AC plugs. Four of them are two-prong, and are rated to provide a standard 15-amp output for most American homes. The last two plugs have a three-prong rating and are rated at 20 amps. The AC output is 1,800 Watts total, with a momentary surge rating that can reach 2,700 Watts. Turn on the Delta 2’s X-Boost mode and it can push 2,200 watts for an extended period of time. EcoFlow says X-Boost is best suited for devices that don’t need exact voltage such as a heater or power tools, and also says you should have only one port for those times. We’d recommend, for example, that you not run a rack of desktop PCs in X-Boost mode due to the lowered voltage EcoFlow uses to reach the sustained higher 2,200 watts.

We’ve seen reports from early reviews of the pure sine wave on the Delta 2 being a little less than pure under heavy loads but looking at the output under a 1,600 watt load, all appeared fine.

Gordon Mah Ung

EcoFlow Delta 2: Performance

We fully discharged the Delta 2 twice in order to condition the battery. Then, we charged it to 100 per cent for run-down testing. We connected a wattmeter to the AC port and measured energy output with a 200-watt incandescent bulb and a small space heater drawing 800 W. Results for both the 200-watt bulb runs reached 80 percent of the Delta 2’s 1,024Wh-rated capacity. Since the output rates can be different whether you’re discharging over AC or DC, we also ran the Delta 2 down over its USB-C port with load set to 20 volts at 3 amps or 60 watts. That’s the typical maximum charge rate for a small laptop if it were dead. Most small laptops can run from 5 watts up to 30 watts under actual use. The DC output was 828 Watt hours, or 80 percent of the 1,024 capacity.

The capacity dropped to 71% under 800 watt loads. The lower capacity could be due to the efficiency and discharge rate of the inverter under heavier loads. We’ll get to the fan noise discussion below.

Gordon Mah Ung

With an 81 percent capacity, that means the Delta 2 gives you an actual effective capacity closer to roughly 821 watt hours—not 1,024 watt hours. That’s only slightly behind the 84 percent efficiency of competing brands.

Gordon Mah Ung

Fan noise

We can’t review the Delta 2 without mentioning one of the things that bugs us the most about it: the fan noise. Under high charge rates and high discharge rates, the Delta 2’s two fans spin at very high RPM, which we measured at 57dBA three feet from the unit when the fans were on. Even worse, it’s a small-fan, shrill 57dBA. When charging at the unit’s maximum 1,200 watts, the fans kick on at full speed. It will not ramp down at lower charges, but it will still run the fans and reach about 50 dBA even at 200 watts.

Fan noises when the battery is being charged can be even more irritating than the noises that are made during discharge or during use. The fans will run at full speed when the Delta 2 is running at more than 900 watts. Power stations are supposed not to make any noise. That means, if you’re running the coffee maker on battery, prepare for some fan noise while you’re at it. It’s probably as annoying as some inverter-based gas generators.

At lower discharge rates, it’s actually not that bad and running a 1990s-era refrigerator, which uses about 172 watts, you can barely hear the Delta 2 over the fridge’s own noise.

We can actually somewhat excuse the Delta 2 (and any power station’s) fan noise on heavy loads, as keeping the inverter and batteries cool is important for longevity and safety.

The fans that activate at more than 120 watts are what bugs us. If you hoped to power medical equipment in your bedroom and it uses more than 120 watts, you’ll have to listen to fans or run an extension cable out of the room.

EcoFlow officials tell us that they will address fan noise in a forthcoming firmware update. The company has done so for other models after the initial release, so here’s hoping it will improve.

Gordon Mah Ung

EcoFlow Delta 2: App support 

Two firmware updates were actually installed to the unit from the box. We think this is a positive sign. This tells us that the company is actively supporting our product and not just never issuing updates.

The Delta 2 now supports iOS and Android devices. This is an upgrade to the original. The Delta 2 can be connected to your Wi Fi network for remote monitoring via the internet. Or, if there is no Wi Fi available, you can connect your phone or tablet directly to the Delta 2 via Wi Fi Direct. It worked fine for us, but a Bluetooth option in addition to Wi-Fi would be even sweeter, as you wouldn’t have to fiddle with the connection without internet. EcoFlow requires a login. This can be irritating for some. We’ve also read reports that you have to connect the app to the internet occasionally, which will be irksome to someone truly off the grid.

The EcoFlow app is intuitive and reliable, according to our experience. We did experience some bad calculations as it was trying to figure out real-time run-time estimates but that’s to be expected. Real-time predictions on how many “hours” of battery life are inherently as unreliable as your car trying to tell you how many miles per gallon are left not knowing you’re about to drive up a bit mountain.

The Eco Flow app allows you to adjust charge rates over AC and DC, set when it turns off, monitor power discharge and charge rate remotely, and also set maximum charge/discharge rates.

Gordon Mah Ung

EcoFlow Delta 2: Modular expansion

The Delta 2’s Extra Battery Port is perhaps the most innovative feature. It can be connected to the right side of your unit. This lets you connect the functional but unimaginatively named Delta 2 Extra Battery to add 1,024Wh of capacity—it’s basically another Delta 2 unit without the AC and DC ports and ups, the total capacity to 2KWh.The even larger 2KWh Delta Max Extra Battery let’s the Delta 2 reach 3KHw.

The best thing about modularity is its weight. Each can be carried separately and stacked nicely.

Although we didn’t review it, EcoFlow also makes a “smart” gas-powered inverter generator This plugs into the same port.

Should you purchase the EcoFlow Delta 2

Overall, the Delta 2 provides class-leading AC rates and decent efficiency. It also allows you to easily increase your capacity. The cherry on top is the ability to upgrade to lithium ironphosphate, which provides much longer duty cycles. A bonus is the 5-year warranty. Our only real complaint is the fan noise. However, we are working on an update to address this issue. The Delta 2 is a great choice for an affordable, powerful, and advanced power station with lots of expansion, at a competitive price of $999 (currently $899 Amazon).