Head-to-head test
EcoFlow RIVER 2 Max vs BLUETTI AC50B
Same $299 price, same 3,000-cycle battery — the AC50B's 700W continuous rating and a fan 17 decibels quieter beat the RIVER 2 Max's extra 64 watt-hours for almost anyone who'll actually plug something real into this.
Written by Wenny ZhengUpdated
Portable Power Tester, Station Arena Test Desk
EcoFlow
RIVER 2 Max
2,030Power Score · Appliance Class
$289.00 list · direct from EcoFlow
BLUETTI
AC50B
1,983Power Score · Device Hub
$279.00 list · direct from BLUETTI
Spec deltas
Take the AC50B. Both of these run $299 and share the same 3,000-cycle LiFePO4 pack, so nothing about price or longevity separates them — the entire decision comes down to two numbers most spec sheets bury below the fold.
The first is continuous output. Both units cap their surge at 1,000W, useful for the split-second jolt of a compressor kicking on, but surge only lasts a second or two. What actually runs a steady appliance is the continuous rating, and there the AC50B holds 700W to the RIVER 2 Max's 500W — the gap between running a space heater or a coffee maker and watching it fault mid-brew.
The second is noise. The AC50B's fan measures 45dB under load, the RIVER 2 Max's 62 — closer to the jump from a quiet conversation to a running vacuum than a rounding error. The RIVER 2 Max claws back capacity, 512Wh to 448, and edges ahead on lifetime cost, 19 cents per kilowatt-hour to 22. For most people who'll actually plug something real into this, the AC50B's extra headroom and quiet fan matter more than an extra 64 watt-hours.
What the Numbers Reveal
Each conclusion stated first — the numbers behind it on one line, the full analysis below.
continuous output
Surge only covers the half-second jolt of a compressor or motor starting; anything that draws steadily above the continuous rating just faults. A 600W space heater or a countertop oven sitting between 500W and 700W runs clean on the AC50B and trips the RIVER 2 Max the moment the surge window closes.
EcoFlow RIVER 2 Max: 500W continuous output, 1,000W surgeBLUETTI AC50B: 700W continuous output, 1,000W surgeboth cap surge at the identical 1,000W ceiling
Why it mattersAnyone running one mid-size steady appliance, not just topping off a phone, should check its continuous draw against 500W before buying the RIVER 2 Max — the AC50B's extra 200W of continuous headroom is the more useful number on this page.
Seventeen decibels doesn't sound like much on a spec sheet, but decibels are logarithmic — the AC50B's 45dB fan is roughly a third the perceived loudness of the RIVER 2 Max's 62. Two feet from a pillow, that's the difference between forgetting it's running and reaching over to unplug it.
BLUETTI AC50B: 45dB fan noise under loadEcoFlow RIVER 2 Max: 62dB fan noise under loadCPAP Overnight scenario needs 320Wh — both units clear it with capacity to spare
Why it mattersAnyone using either unit overnight near a bed, in a home office, or in a small camper should weight the noise spec over the capacity number — both have capacity to spare, only one is quiet enough to ignore.
Capacity
Three cents a kilowatt-hour, 19 against 22, is real but small — nothing like the multi-times gaps that show up when cycle ratings actually differ between two units. This is the honest reason to pick the RIVER 2 Max: it's a genuinely cheaper battery to run, just not by enough to outweigh a 200W output gap or a fan that's a third as loud.
EcoFlow RIVER 2 Max: $299, 512Wh, $0.19 cost per lifetime kWhBLUETTI AC50B: $299, 448Wh, $0.22 cost per lifetime kWhboth rated 3,000 cycles
Why it mattersBuyers optimizing purely for cost per kilowatt-hour should take the RIVER 2 Max, but shouldn't expect the savings to be the deciding factor — it's a rounding error next to output and noise.
solar input
Solar wattage only matters relative to the tank it's filling, and here the two ratios land within minutes of each other. The 20W solar gap on the spec sheet isn't a real-world refill advantage for either unit.
EcoFlow RIVER 2 Max: 220W solar input, 512Wh capacityBLUETTI AC50B: 200W solar input, 448Wh capacity
Why it mattersDon't let the RIVER 2 Max's larger solar number sway a buy decision on its own — recharging from sun alone, both units refill at essentially the same rate.
The specific dimensions that decide these two units — everything else is a tie.
Lifetime Value
Selected because: Same price and cycle count reduce the whole cost story to a 3-cent-per-kWh gap driven purely by capacity — worth stating plainly since it's the one place EcoFlow wins outright.
cost / lifetime kWh
This is the one column where the RIVER 2 Max wins outright, and it's a clean story: identical price, identical 3,000-cycle rating, so the entire gap comes from capacity. 512Wh against 448Wh nets 19 cents per lifetime kilowatt-hour for the EcoFlow against 22 cents for the AC50B.
Three cents doesn't move a budget. Run either one regularly and the gap between them totals a few dollars over the battery's working life — nowhere near the double- or triple-digit multiples that show up when cycle ratings actually differ between two units. Treat this column as a tiebreaker, not a verdict.
What the Specs Don't Tell You
Selected because: Noise and surge-ratio both fire; the noise gap is the loudest signal on the page for anyone using this indoors or overnight.
Two flags fire here and they point opposite directions. The surge-ratio card is the RIVER 2 Max's best defense: doubling its own 500W continuous rating to reach the shared 1,000W surge ceiling reads as more inverter headroom on paper. The noise card is the one that actually bites — 45dB for the AC50B against 62 for the RIVER 2 Max, and that's not a paper spec, it's what you hear.
Both switch to battery in standby class, 20 milliseconds for the AC50B and 30 for the RIVER 2 Max — close enough that a router or a lamp never notices the cutover either way. That one's a wash; spend the attention on the fan instead.
Your Life, Your Pick
Selected because: Every scenario except CPAP overloads both units, and CPAP is a headroom win for EcoFlow that noise practically overturns — where the page's real tension shows up.
Every scenario except CPAP overnight overloads both units by roughly two to twelve times their capacity — camping weekends, blackouts, tailgates, van life, none of these is a one-battery job at this size, and both fail together. The only scenario either one actually wins is the CPAP night, where the RIVER 2 Max's bigger tank leaves a bit more in reserve on paper.
But a CPAP night barely taxes either battery, so 'more reserve' is leftover capacity nobody spends. The spec that actually matters at a bedside is the one this table doesn't score: fan noise. On that count the AC50B is the one worth the second look, reserve capacity aside.
Brand Trust
Selected because: Cross-brand pair — EcoFlow's deeper ecosystem and recent recall history against BLUETTI's value focus and support inconsistency.
EcoFlow is the bigger, faster-moving company — the largest ecosystem in the category, the fastest charging tech, and the most active community by a wide margin. That momentum comes with scar tissue: an October 2025 recall on the DELTA Max 2000 for overheating risk, and an early-2025 attempt to paywall app features that the community pushed back hard enough to kill.
BLUETTI counters with the better value story — the strongest capacity-to-price ratio in the market and, per app-store ratings, the best-reviewed app of any major brand. Its weak point is support: heavily email-based with China-timezone delays, split between smooth prepaid-label swaps and multi-week troubleshooting loops. Buying direct from BLUETTI's own site is the reported fix.
Strengths & trade-offs
EcoFlow RIVER 2 Max
Strengths
- +Lighter by 1.4 lb
- +Larger battery capacity
- +Faster solar charging
Trade-offs
- –Can receive complaints about fan noise under heavy load.
BLUETTI AC50B
Strengths
- +Costs $10 less
- +Higher AC output
Trade-offs
- –No major technical downsides compared to rival.
Will It Power Your Gear?
Scenario math and per-appliance runtimes, modeled from the spec record.
Scenario verdicts
We ran the math on six real-world scenarios. Here's which unit survives your actual life.
SCN-01 · 2 nights · needs 2,100Wh
Weekend Camping
Two nights off-grid with essential comfort
Neither unit
A two-night camping load runs past 2,000 watt-hours once lights, a fan, and device charging add up, and both of these fall well short trying to cover it alone. Neither is the right size for this scenario — pack a solar panel or start with something in the 1,500Wh-plus class.
Battery budget usedlower = more headroom
LOAD Phone Charger 15W×6h · LED Lights 40W×8h · Box Fan 75W×14h · CPAP Machine 40W×16h
SCN-02 · 8 hours · needs 1,645Wh
8-Hour Blackout
Keep the essentials running through a night without power
Neither unit
A full eight-hour blackout with a fridge running lands well past what either 448-512Wh battery can usably hold after inverter losses. Both switch to battery fast enough that nothing in the house notices the cutover, but neither carries a real overnight outage alone — this is the scenario that argues for a bigger single unit, not a coin flip between these two.
Battery budget usedlower = more headroom
LOAD Fridge 150W×8h · Router + Modem 20W×8h · LED Lights (4 bulbs) 40W×6h · Phone Charger 15W×3h
SCN-03 · 8 hours · needs 320Wh
CPAP Overnight
Sleep therapy without interruption — the #1 medical use case
RIVER 2 Max
A CPAP night draws around 320Wh, a fraction of what's on board either battery — the RIVER 2 Max's bigger tank leaves slightly more in reserve on paper, using 74% of capacity to the AC50B's 84%. But at a bedside, reserve capacity nobody spends matters less than what you hear: the AC50B's fan runs at 45dB against 62 for the RIVER 2 Max.
Battery budget usedlower = more headroom
LOAD CPAP Machine 40W×8h
SCN-04 · 8 hours · needs 910Wh
Remote Workday
Full work day off-grid without power anxiety
Neither unit
Neither unit can fully handle this scenario (needs 910Wh). You'd need a higher-capacity station or to cut back on usage.
Battery budget usedlower = more headroom
LOAD Laptop 60W×8h · External Monitor 30W×8h · Router + Modem 20W×8h · Phone Charger 15W×2h
SCN-05 · 4 hours · needs 670Wh
Tailgate Party
Game day power for the crew
Neither unit
Neither unit can fully handle this scenario (needs 670Wh). You'd need a higher-capacity station or to cut back on usage.
Battery budget usedlower = more headroom
LOAD Blender 400W×0.5h · LED TV (55") 80W×4h · Bluetooth Speaker 15W×4h · Phone Charger (×3) 45W×2h
SCN-06 · 24 hours · needs 4,685Wh
Van Life Daily
A full day of mobile living — the ultimate endurance test
Neither unit
Neither unit can fully handle this scenario (needs 4,685Wh). You'd need a higher-capacity station or to cut back on usage.
Battery budget usedlower = more headroom
LOAD Mini-Fridge 150W×24h · Laptop 60W×4h · Phone Charger 15W×3h · LED Lights 40W×5h · Fan 75W×8h
The Load Test
RUNTIME = (Wh × 0.85) ÷ LOAD
None of the six scenarios above exactly yours? Build it. Toggle what you'd plug in; both units are tested against the combined draw.
Essentials
Comfort & Convenience
High-Draw Appliances
Test duration
8h
Continuous draw
205W
Projected runtime
For this load: RIVER 2 Max runs 2.1h vs 1.9h.
$289 list · direct from EcoFlow
Modeled from the spec record — same math as the tables below. Methodology
Runtime by appliance
Real-world runtime estimates for common appliances, modeled at 85% inverter efficiency.¹
Essentials
The basics you need runningscale 0–29hComfort & Convenience
Makes off-grid life actually enjoyablescale 0–5.8hHigh-Draw Appliances
These reveal the real limits¹ Runtime = (capacity × 0.85) ÷ appliance watts. Within each group, all bars share one time scale (the group's longest runtime), so lengths are comparable across appliances; identical runtimes collapse into a single blue/orange bar. Actual runtime varies with battery age, temperature, and simultaneous loads — see methodology.
Conclusion
July 14, 2026
Verdict: the AC50B
Take the AC50B, but know what you're trading. Dollar for dollar these two tie: $299, 3,000 rated cycles, a 1,000W surge ceiling apiece. The RIVER 2 Max is technically the cheaper unit to own over its life — $0.19 per lifetime kilowatt-hour against the AC50B's $0.22 — because its 512Wh tank is 64Wh bigger for the same money. That's real, and it's the honest reason to pick EcoFlow. But the number that actually changes what you can plug in is continuous output: 700W on the AC50B against 500W on the RIVER 2 Max, and a steady 600W space heater or coffee maker runs fine on one and trips the other, surge ceiling or not. Add a fan that measures 45dB against 62 — the gap between a whisper and a window air conditioner — and the AC50B is the one you can leave running in a bedroom or office without noticing it. Flip this only if raw capacity and the lowest possible per-kWh cost matter more to you than what one steady appliance can draw; then the RIVER 2 Max's bigger tank and faster 100W USB-C port are the better fit.
Editor-assigned confidence, based on cited owner research and spec analysis.
List prices as of July 14, 2026. The links below open EcoFlow's and BLUETTI's current prices.
$279.00 list · direct from BLUETTI
or check the RIVER 2 Max price$289.00 list
Written by Wenny Zheng, Portable Power Tester · Station Arena Test Desk · Updated July 14, 2026
Measured Data
Benchmark scores and the full spec record, side by side.
Benchmark scores
Not rated for both units (minimum threshold unmet): UPS, Tailgating.
Full specifications
ᵈ Derived: price ÷ rated capacity. See the data behind our comparisons →
Comparison ToolAdd more power stations, side by sideOpen Tool →How these numbers are produced
Numeric verification
Every figure on this page traces to our spec database or arithmetic on it — no estimated numbers.
Owner claims
Statements about owner experience are cited to published reviews — see Sources & Research Notes below.
Runtime model
Runtime = (rated capacity × 0.85 inverter efficiency) ÷ device wattage. Solar recharge estimates assume panels deliver 70% of rated output. Cold weather, battery age, and stacked loads reduce real-world results.
Power Score
Computed from 14 published spec dimensions, weighted per use-case bench. Higher is better; a unit must meet a bench's minimum threshold to be rated.
See the full weight table and data sourcing on our methodology page →Class ranking (the star rating)
Each unit's star score is a category ranking, not customer reviews — no buyer opinions feed it. We score every station on size-independent quality (value, output, portability, endurance, ports, warranty, and more), then percentile-rank it against the other units in its capacity class, so a class-leading compact unit and a class-leading whole-home unit can both earn 5★. Here, RIVER 2 Max rates 3.9/5 (33rd percentile of 19 Compact-class units), and AC50B rates 4.9/5 (95th percentile of 22 Personal-class units).
How the class ranking is computed →Test Notes & Caveats
Hidden gotchas and advantages we spotted that you won't find on the product page.
Not Even Close
45 decibels against 62 sounds like a modest gap until you remember decibels are logarithmic — the AC50B's fan is roughly a third as loud, perceptually, as the RIVER 2 Max's under the same load. Two feet from a pillow or a desk, that's the number that decides it, not the extra 64 watt-hours the RIVER 2 Max is carrying.
Surge Power: Inverter Quality Indicator
The RIVER 2 Max has a 2× surge-to-continuous ratio vs the AC50B's 1.4×. A higher ratio (≥2×) means the inverter handles motor startup surges better. That's critical for fridges, AC compressors, and power tools that briefly draw 2-3× their rated wattage. The AC50B may trip when starting these appliances even though its continuous wattage looks sufficient.
UPS Speed: standby (<20ms) vs basic standby
The AC50B switches to battery in 20ms (standby (<20ms)), while the RIVER 2 Max takes 30ms (basic standby). Most electronics handle this fine, but sensitive server equipment may hiccup. This matters if you're using it as a home UPS for always-on equipment.
Full record above — the Test Desk pick is the AC50B.
Check AC50B price →or check the RIVER 2 Max priceOwnership Analysis
What happens after you buy — true cost of ownership, brand trust, and growth potential.
Lifetime value
Service lifeyears at one full cycle per day
Lifetime energy delivered
Cost per delivered kWh
│ warranty ends · Reaching the cycle rating means ~80% capacity remains — degraded, not dead.
Analyst note
The AC50B is cheaper to buy, but the RIVER 2 Max is cheaper to own. At $0.19/kWh over its lifetime vs $0.21/kWh, the RIVER 2 Max's higher cycle life and capacity make each dollar go further over the years.
Brand trust
EcoFlow
Ecosystem
The deepest bench in the category — a dozen-plus models from RIVER 3 up through DELTA Pro Ultra X, solar panels, and smart home panels, with the fastest charging tech across the lineup.
Support
US-based phone, email, and chat, but the reviews split hard: plenty of hassle-free prepaid-label swaps alongside real complaints about long waits and refurbished replacements. Buying through Costco or Amazon adds a safety net either way.
Community
Largest community in the space — Reddit r/Ecoflow_community (~31K members), multiple Facebook groups, and an official community forum
App experience
Rated 4.6/5 iOS (~8,400 ratings) · 4.2/5 Android (~17,000 ratings)
Unique strength
Fastest-charging technology (X-Stream), deepest product ecosystem, and most active innovation cadence. Supports up to 180kWh modular expansion with DELTA Pro Ultra X.
Worth knowing
The October 2025 DELTA Max 2000 recall over overheating risk is worth knowing before buying into the ecosystem, and a paywalled-app-features test earlier that year only got walked back after the community pushed back.
BLUETTI
Ecosystem
One of the widest lineups in the category, budget to flagship, including sodium-ion cold-weather units and vehicle solar hubs most rivals don't touch.
Support
The most inconsistent of the major brands — heavily email-based, with China-timezone delays. Buying direct from BLUETTI's own site reportedly produces smoother outcomes than third-party retailers.
Community
Active and growing — Reddit r/bluetti has a dedicated community. Second-largest after EcoFlow in engagement.
App experience
Rated 4.5/5 iOS and Android — tied for best app experience in the category. V3.0 UI redesign was well-received.
Unique strength
The strongest capacity-to-price ratio in the category, and per app-store ratings, tied for the best app experience of any brand here.
Worth knowing
Customer support inconsistency is the #1 risk factor. Older/discontinued units may become unrepairable — no spare parts policy for some models. Some reports of erratic communication from support agents.
Analyst note
EcoFlow brings more scale and faster charging tech, with a recent recall and a paywall misstep on its record. BLUETTI brings the better price-to-capacity math and a better-reviewed app, with support that's genuinely hit or miss depending on where you buy. Neither issue should override what these two units actually do for you — output headroom and fan noise — but keep receipts either way.
Growth path
RIVER 2 Max
FIXED CAPACITYFixed at 512Wh, with no expansion — so size it for your needs up front rather than planning to add capacity later.
Accepts up to 220W of solar. Limited to a single portable panel.
Adequate ports for most setups, but heavy users may want a power strip.
AC50B
FIXED CAPACITYFixed at 448Wh, with no expansion — so size it for your needs up front rather than planning to add capacity later.
Accepts up to 200W of solar. Limited to a single portable panel.
Limited ports. You'll likely need a power strip or splitter.
Realistic full solar rechargeat 70% of rated panel output — see methodology
Analyst note
Neither expands, and that's no knock on either — each is a complete unit at a fixed size. Buy the capacity that covers your needs now (the RIVER 2 Max gives you the larger ceiling); you can't add to either later.
What Owners Report
Patterns from published owner reports and long-term reviews — every claim cited to its source below.
EcoFlow RIVER 2 Max
Coverage of the RIVER 2 Max leans hard on two things: how little it weighs and how fast it refills. At roughly 13 lbs it's lighter than several Li-Ion competitors in its classA1, and EcoFlow's X-Stream charging gets it from empty to full in about an hour through multiple charging pathsA2 — genuinely fast for a battery this size.
The app draws consistent praise for being simple to run over Wi-Fi or Bluetooth, covering charge level, settings, and charge-speed control from a phoneA3. In one field test it ran a telescope, a 65-inch TV, two laptops, and phones through a 4-hour event with power to spare, on a pack rated for roughly 3,000 cyclesA4 — real load, not a lab number.
“512Wh in a light package of about 13 lbs, lighter than some of its closest competitors that use Li-Ion chemistry.”
Sources
storagereview.com · backuppowerhub.com · gagadget.com · ecoflow.com · thecampingnerd.com · thetechnologyman.com · bestbuy.com
BLUETTI AC50B
Owner and reviewer coverage of the AC50B centers on how genuinely portable it is for a 700W unit — at 14.8 lbs, reviewers call it meaningfully lighter than BLUETTI's own step-up AC70 at 21.4 lbs, a real one-hand-grab difference rather than a marketing footnoteB2.
The battery itself draws steady praise: a 448Wh LiFePO4 pack rated for 2,500-plus cycles to 80%, with output up to 700W continuous and a 1,000W Power Lifting surge modeB1. Charging is the other consistent highlight — about 3 hours standard, dropping to 1.25 hours with the optional 480W Turbo charger, with 0-80% in 45 minutesB3. None of the coverage digs into fan behavior specifically, so treat the 45dB figure as a manufacturer spec the field reviews don't independently confirm or dispute.
“A 448Wh LiFePO4 battery with 700W output (1,000W Power Lifting), rated for 2,500+ cycles to 80% — years of reliable use.”
Sources
amazon.com · backuppowerhub.com · the-gadgeteer.com · t3.com · bluettipower.com · greattips3s.com
Sources & Research Notes
Every owner claim in this report is traceable to a published source. The bracketed references above resolve here.
Recurring owner themes
- Light weight, fast roughly-one-hour charging, and a simple capable app are the standout praise for this 512Wh unit. [RIVER 2 Max · 3 entries]
- Affordable, genuinely portable LFP unit with 700W output, 2,500+ cycles, fast Turbo charging, and B80 expandability. [AC50B · 3 entries]
- A1
“512Wh in a light package of about 13 lbs, lighter than some of its closest competitors that use Li-Ion chemistry.”
storagereview.com / backuppowerhub.com — RIVER 2 Max review · 2026 · [positive]
- A2
“Fully charges in about 60 minutes via X-Stream charging — far faster than most portable power stations — with multiple charging options.”
gagadget.com / ecoflow.com — RIVER 2 Max review · 2026 · [positive]
- A3
“The EcoFlow app offers simple remote control and monitoring over WiFi and Bluetooth — view charge levels, customize settings, and adjust charging speed from a phone.”
thecampingnerd.com / ecoflow.com — RIVER 2 Max review · 2026 · [positive]
- A4
“Upgraded LFP chemistry rated for about 3,000 cycles, roughly a decade of everyday use; in field testing it powered a telescope, a 65-inch LED TV, two laptops, and phones through a 4-hour event with power to spare.”
thetechnologyman.com / bestbuy.com owner reviews — RIVER 2 Max · 2026 · [positive]
- B1
“A 448Wh LiFePO4 battery with 700W output (1,000W Power Lifting), rated for 2,500+ cycles to 80% — years of reliable use.”
amazon.com / backuppowerhub.com — AC50B review · 2026 · [positive]
- B2
“At 14.8 lbs it's meaningfully lighter than the AC70 (21.4 lbs) — a genuinely portable sub-15-lb unit with a long-cycle battery and 700W output at an easy-to-justify price.”
backuppowerhub.com / the-gadgeteer.com — AC50B review · 2026 · [positive]
- B3
“Standard AC charging is about 3 hours, dropping to 1.25 hours with the optional 480W Turbo charger; 0-80% in 45 minutes.”
amazon.com / t3.com — AC50B review · 2026 · [positive]
Research compiled July 14, 2026.
Who Should Buy Which
Buy the RIVER 2 Max if you…
- →You want the biggest tank and the cheapest lifetime cost at this price, and you're not running anything that draws a steady 500-700W — lights, laptops, phones, small electronics.
- →You care about fast device charging: the 100W USB-C port tops a modern laptop quicker than the AC50B's 65W port.
Buy the AC50B if you…
- →You're running one real steady appliance — a space heater, a countertop oven, a coffee maker — anything between 500W and 700W continuous, where the RIVER 2 Max's rating simply won't hold.
- →This is living in a bedroom, home office, or small camper overnight, where a fan that measures 45dB instead of 62 is the difference between forgetting it's on and reaching over to unplug it.
If neither fits
If your actual load is a weekend of camping, an overnight blackout, or a van-life day, both of these are the wrong size outright — every one of those scenarios runs past what either 448-512Wh battery holds by a wide margin. Start at 1,500Wh or larger, or plan on stacking a second unit from day one.
The Bottom Line
Same price, same cycle rating — this comes down to two numbers spec sheets bury: 700W continuous against 500W, and 45 decibels against 62. The AC50B runs more real appliances and disappears into the background wherever you park it; the RIVER 2 Max answers with more capacity and a genuinely cheaper $0.19 per lifetime kilowatt-hour.
For most people who'll actually plug in something with a real steady draw, or run this near a bed, take the AC50B. Take the RIVER 2 Max only if raw capacity and the lowest lifetime cost outrank what one mid-size appliance can pull — and even then, the margin you're buying is three cents a kilowatt-hour.
Frequently Asked Questions
Answers drawn from the spec record and cited owner research.
Is the BLUETTI AC50B or EcoFlow RIVER 2 Max the better buy?
At the same $299 price, it comes down to what you'll actually run. The AC50B's 700W continuous output handles more real appliances than the RIVER 2 Max's 500W, and its fan measures 45dB against 62 — meaningfully quieter for bedside or indoor use. The RIVER 2 Max answers back with more capacity, 512Wh to 448, and a genuinely cheaper $0.19 per lifetime kilowatt-hour against $0.22, so if raw capacity and lifetime cost matter more than output headroom or noise, take the EcoFlow instead.
Can either one run a space heater or coffee maker?
Check the wattage first. The AC50B's 700W continuous rating covers most single mid-size appliances in that range; the RIVER 2 Max's 500W continuous rating doesn't, even though both share the same 1,000W surge ceiling for a compressor's startup jolt. Surge only lasts a second or two — a steady draw above the continuous rating just faults the unit.
Which one is quieter for overnight or CPAP use?
The AC50B, by a wide margin — 45dB under load against the RIVER 2 Max's 62. Both comfortably power a CPAP through the night on capacity alone since a full night's use is a fraction of either battery, so the deciding factor for bedside use is fan noise, not watt-hours.
Is the RIVER 2 Max actually cheaper to own?
Yes, on paper. Same $299 price and 3,000-cycle rating, but its bigger 512Wh tank works out to $0.19 per kilowatt-hour delivered over its life against the AC50B's $0.22. It's a real advantage — just a small one, a few dollars over the battery's working life, not enough to outweigh a 200W output gap for most buyers.
Does either unit expand with an add-on battery?
No. Both are closed systems as sold — whatever capacity you buy is the capacity you get, with no supported expansion battery for either unit at this price point. If your needs might grow past 448-512Wh, plan for a bigger single unit rather than counting on a future add-on.
Where to buy
EcoFlow RIVER 2 Max
$289.00
$289.00 list · direct from EcoFlow
BLUETTI AC50BPick
$279.00
$279.00 list · direct from BLUETTI
Prices may vary by retailer and are subject to change.