EcoFlow RIVER 520 Gen4: Release Date, Specs and What We Know

At a glance

Status

Announced, pre-release

Announced

4 September 2026, IFA 2026 in Berlin

Capacity

512Wh

Battery chemistry

LFP (lithium iron phosphate)

Continuous AC output

500W

X-Boost

Up to 1,000W for selected compatible devices

Weight

Approximately 4.6 kg

UPS switchover

Under 10ms

0–80% charge

Approximately 50 minutes (X-Stream 4.0)

European availability

Announced for Q1 2027

US availability

UNKNOWN — not announced

Price

UNKNOWN — not announced

Amazon availability

UNKNOWN — no confirmed listing or ASIN

TopPremiumPicks status

Pre-release research — not a review

Current status

EcoFlow unveiled the RIVER Gen4 series at IFA 2026 in Berlin on 4 September 2026, showing both the RIVER 260 Gen4 and the RIVER 520 Gen4 on its stand. These are production products with announced availability windows, not concepts.

What does not exist yet is a dedicated EcoFlow product page for the RIVER 520 Gen4, a retailer listing, a price, or an Amazon listing. So the specifications below come from EcoFlow's announcement material and from journalists who saw the units at the show, and the commercial details that usually decide a purchase are simply not published.

Officially confirmed specifications

Everything in this table comes from EcoFlow's own announcement. Nothing estimated or carried over from older RIVER models appears here.

What 512Wh and 500W actually mean

Two numbers decide what any power station can do. Capacity (512Wh) is how much energy is stored; continuous output (500W) is how much can be drawn at once. A 512Wh battery is a weekend-scale unit: phones, laptops, cameras, lights, a router, a Starlink terminal, a CPAP, a portable fridge cycling on and off. It is not a whole-home backup battery, and a 500W ceiling rules out kettles, hair dryers, microwaves and most space heaters regardless of capacity.

If you want to see how 512Wh maps onto your own devices, our power station size and runtime calculator works both directions, and what size power station you need explains the sizing logic behind it.

X-Boost explained

EcoFlow rates the RIVER 520 Gen4 at 500W continuous, with up to 1,000W through X-Boost for selected compatible devices. X-Boost is EcoFlow's technique for running resistive appliances above the inverter's rated output by lowering the voltage delivered to them — the appliance runs, just more slowly or at lower power. It is a genuinely useful feature, but it is not a second inverter rating: EcoFlow states it applies to compatible devices, and sensitive electronics and motor-driven appliances are not the target. EcoFlow has not published a compatibility list for this model.

Ports and the 140W bidirectional USB-C

EcoFlow states the RIVER 520 Gen4 carries six outputs with fast charging on every USB-C port. The headline connector is a single 140W bidirectional USB-C port: it charges devices at high power, and it also charges the unit itself — from a USB-C wall charger, from solar, or from a car, using the appropriate adapters. For a unit meant to live in a backpack, dropping the traditional charging brick matters more than the wattage does.

Third-party reported: The Verge describes the 520 Gen4 as having a pair of AC jacks alongside its USB selection. EcoFlow has not published a full port map, so the exact AC outlet configuration, the USB-A count and any DC outputs remain unconfirmed.

Charging and X-Stream 4.0

EcoFlow's X-Stream 4.0 fast-charging system, with active thermal management, takes the RIVER 520 Gen4 from 0 to 80% in approximately 50 minutes (the smaller 260 Gen4 is quoted at 42 minutes). EcoFlow also lists solar and car charging through the 140W USB-C port with compatible adapters, and names its 60W Lightweight Portable Solar Panel as the matched panel for the series.

Not published: AC input wattage, the full 0–100% charge time, maximum solar input, and complete vehicle charging specifications. Those are the figures that decide how practical solar top-ups really are, so we are leaving them blank rather than borrowing numbers from earlier RIVER models.

UPS functionality and Emergency Power Mode

Both Gen4 models support UPS functionality with a switchover time under 10ms, which is quick enough for a desktop computer, a router or a home network cabinet to ride through a cut without rebooting. That makes a small unit like this useful at a desk year-round rather than only on trips.

EcoFlow also describes an Emergency Power Mode that safely extends the usable discharge range once the display reads 0%, intended to keep calls, messages and navigation available. EcoFlow presents this as an industry first, based on its own assessment of comparable products.

Refrigerator Runtime Mode

Refrigerator Runtime Mode adapts power delivery to refrigerator loads to extend cooling time during an outage. Fridges spend most of their time idle and spike hard when the compressor starts, so tailoring delivery to that pattern is a sensible use of a small battery.

Third-party reported: The Verge characterises the 520 Gen4 as enough to keep a standard US fridge running for about four hours during a blackout. That is a practical characterisation from a journalist, not a guaranteed runtime and not an EcoFlow specification — real fridges vary enormously.

Size, weight and EcoFlow's compactness claims

The confirmed figure is the weight: approximately 4.6 kg for 512Wh. Everything else in this area is an EcoFlow claim, measured by EcoFlow against a comparison set EcoFlow selected:

• Approximately 59.1% smaller than the RIVER 2 Max at comparable capacity
• Approximately 23.5% lighter than the RIVER 2 Max
• Active idle power approximately 30% lower than the industry average
• Approximately 99% state of charge retained after a year under controlled storage conditions
• “Smallest in its class” positioning for the RIVER Gen4 series
• One of the smallest and lightest solar generator setups on the market when paired with EcoFlow's 60W panel

EcoFlow footnotes these size, weight, idle-power and class claims as based on its own measurements and on selected comparable products available at the time of publication. They are plausible and specific, but they are marketing comparisons rather than independent results, and dimensions for the unit have not been published at all.

RIVER 520 Gen4 vs the RIVER models you can buy today

EcoFlow's own reference point is the RIVER 2 Max, the 512Wh model the 520 Gen4 is measured against — same capacity class, much larger body according to EcoFlow's figures. The generational story here is density, not capacity: you are not being offered more energy, you are being offered the same energy in less to carry.

Among current models we cover, the closest points of reference are the Anker SOLIX C300 and the EcoFlow RIVER 3 Plus, both smaller 280–300Wh-class units aimed at the same backpack-scale use — our C300 versus RIVER 3 Plus comparison sets out where each one lands. A 512Wh Gen4 unit would sit a clear step above both on capacity. We are not going to publish a spec-by-spec table against them until EcoFlow publishes dimensions, solar input and full charge times.

RIVER 260 Gen4 vs RIVER 520 Gen4

The two Gen4 models were announced together. The RIVER 260 Gen4 offers 256Wh, 300W of AC output, up to 600W with X-Boost, five outputs and approximately 3.0 kg, reaching 80% charge in about 42 minutes; EcoFlow positions it for day trips and everyday mobile use, and it is announced for Europe in Q4 2026 — ahead of the 520. The RIVER 520 Gen4 doubles the capacity to 512Wh, raises continuous output to 500W with up to 1,000W X-Boost, adds a sixth output, and is aimed at overnight trips, more devices at once and light home backup.

Both share LFP cells, the sub-10ms UPS, X-Stream 4.0 and the 140W bidirectional USB-C port. Choose on capacity and output: the 260 for a day out of the house, the 520 for a night away or a power cut.

Release date, pricing and US availability

Announced availability is European: the RIVER 260 Gen4 from Q4 2026 and the RIVER 520 Gen4 following in Q1 2027. No exact release day has been given for either.

Pricing is unknown. EcoFlow has said pricing will be announced closer to release, and no figure exists in any currency. We are not going to estimate one from earlier RIVER models.

US availability is unknown. EcoFlow has announced European availability and nothing about a US launch, a US price or US retailers, and there is no Amazon listing and no ASIN. European availability is not a US release date, and we will not treat it as one. If EcoFlow announces US plans, this page is updated and the update log records the date.

What remains unknown

• Final price, in any currency
• Exact release date within Q1 2027
• US launch
• US price
• US retailers
• Amazon US availability
• ASIN
• Surge output, if specified separately from X-Boost
• The complete AC outlet configuration
• The complete USB-A configuration
• DC output details
• Maximum solar input
• Complete vehicle-charging specifications
• AC input wattage
• Full 0–100% charge time
• Dimensions
• Operating-temperature range
• IP / weather-resistance rating
• Cycle-life specification
• Warranty terms
• Expansion-battery compatibility
• App details
• Wi-Fi and Bluetooth details
• Included accessories

Should you wait, or buy a current model?

For US readers, waiting for this specific unit is not a plan you can currently make: there is no announced US launch and no price. If you need portable power this season, the best small portable power stations covers the backpack-scale class the RIVER Gen4 competes in, and the camping shortlist covers trips specifically. Broader picks sit in the overall power station guide, and everything we publish in the category is on the portable power station hub.

Waiting makes more sense for European buyers who specifically want the smaller, lighter package at 512Wh and are not in a hurry — the density gain is the entire point of this generation. One thing that does not change either way is the chemistry: the Gen4 units use LFP cells, and LiFePO4 versus lithium-ion explains why that matters for lifespan more than for headline capacity.

Frequently asked questions

Update log

This page keeps the same address through the product's life. It is updated as final specifications appear, when pricing is announced, if a US launch is confirmed, when preorders open, when retailers list it and if an Amazon listing appears.

• September 11, 2026 — Page published from EcoFlow's IFA 2026 announcement (4 September 2026) and independent launch coverage. Price, exact release date, US availability, dimensions, IP rating, warranty, solar input and Amazon listing recorded as unknown.

Sources

• EcoFlow's IFA 2026 announcement and specification claims: EcoFlow press release, 4 September 2026
• Availability windows, port observations and the refrigerator characterisation: The Verge, 7 September 2026