We can't help but swoon over phones with big, 3,500mAh batteries. There's something magical about the promise of untethered longevity, conjuring images of hitting the open road for some carefree, off-grid adventure. So imagine what you could do with a portable battery packing 33 times the energy capacity of the Samsung Galaxy S8 Plus. That's River, the first product from the upstarts at EcoFlow, and it’s a gadget I never thought I'd want until I lived with a prototype for a week.

What is it?

River is a 116,000mAh (412Wh) battery that weighs 11 pounds and is capable of supplying a total of 500 watts (AC + DC) to your electrical devices. That means it has enough capacity to recharge a laptop about 5 to 9 times, a phone about 30 times, or a GoPro about 80 times, according to EcoFlow. Flip it to AC mode and it'll power a guitar amplifier for about 15 hours of subway busking, or a mini fridge for about 10 hours of cold beer at your next tailgate party.

EcoFlow pitches River as both emergency backup power for the home, and as the ideal companion for a life lived beyond the reach of the power grid. It's this latter category that's most appealing (and most practical since River isn't powerful enough to drive a sump pump in a flooding basement). River’s perfect for a surf safari along the coast, a glamping weekend, or that Mongolian motorcycle adventure you've always dreamed about.

What's special about it?

EcoFlow might be a new company, but it touts DJI DNA. Notably, CEO Eli Harris and product manager Frankie Zheng both hail from the young Chinese company that dominates consumer drone sales around the world.

EcoFlow cites a few features that make River stand out from products like the 434Wh Anker Powerhouse and 428Wh Goal Zero Yeti. To start with, it offers a slightly wider operating temperature range of -20 to 60 degrees Celsius, making it the better choice for extreme environments. River’s also capable of producing more AC power at 300 watts, and features a wider range of outputs — 11 ports in total — all of which can be used simultaneously to charge or power your devices. EcoFlow also claims that River has the best battery management capabilities in its class, making it intelligent enough to sense newly connected devices and then supply just the right amount of power required — no more, no less.

Is it good? 

Yes it's good, based on the 10 days I've been using a 110V US prototype. Are there kinks? A few, but nothing major. EcoFlow knows about the issues and says they'll be sorted by the time production units ship. For example, the USB-C to USB-C cable supplied by Apple with my MacBook couldn't be used to charge the laptop off River's USB-C jack. The same cable did, however, charge my LG 360 camera. This discrepancy was due to a pin misalignment on my particular batch of River prototypes, according to EcoFlow, and LG allows for a wider range of signal tolerance than Apple. Nevertheless, River offers so many output options that I could still charge my MacBook by plugging into River's AC jack, or via a standard USB jack using the USB-A to USB-C cable I carry in my bag. 

I dare say it was a fun challenge to find enough devices to deplete River's battery. A fully charged River lasted four days under heavy use, charging phones, speakers, laptops, tablets, and cameras off the DC ports. In order to deplete it more quickly, I eventually resorted to running devices off River's AC ports, including my home theater projector, and a DJI-supplied charger from a Mavic Pro. 

I also tried EcoFlow's optional 50-watt solar panel. It ships with two outputs: one USB-A to top off a phone, for example, and another outlet to charge River. I didn't have enough sunlight or time to fully charge River off solar. In my testing, I went from a dead battery to 9 percent in four hours one morning, with partly to mostly cloudy skies here in northern Europe. That’s less than ideal, clearly, and puts me closer to 40 hours for a full charge compared to the 10-to-15-hour claim made by EcoFlow.

Am I happier or more fulfilled? 

You know what, I am happier. There's a linear relationship between the number of battery-powered devices I own and the charging stress they create. I did most of my River testing from the beach where I own a small house with limited access to power. Normally, seeing all the low-battery indicators on the devices I regularly use (a laptop, tablet, smartphone, fitness watch, Bluetooth speaker, projector, drone, and cameras) would fill me with a low-level sense of dread. But having the River along with its massive reserve of electrons helped me relax — and that's a very powerful feeling. The solar charger is a feel-good bonus.

I'm also a bit smarter now thanks to River's display which gives real-time insight into the power consumed by my gear.

Should you get one? 

Ah, here we are at the ol' should you get one part of the review. Well, consider this: Anker's a brand you're almost certainly familiar with, and its PowerHouse battery of similar capacity is a little bit lighter, a little bit smaller, but slightly less feature-rich than the River — the PowerHouse is available right now for $499. River's from a brand-new company offering early-bird pricing of $459 on Indiegogo for July delivery. After that, it'll climb to $499 before topping out at a projected retail price somewhere between $599 and $699.

At $459 I think River's a bargain if you're in the market for a big-ass battery. At $499 it's worth serious consideration. But when the price climbs to $599 and above I'd be leery of betting that much cash on a newcomer's first product.

Update April 13th, 3:14AM: After launching on Indiegogo, EcoFlow has amended some of the key specifications provided to The Verge for the purposes of our review. Chiefly, it will not maintain 100 percent of its charge after one year on the shelf as originally claimed. It’s also IP63 certified, not the more rugged IP67, and you can expect it to charge a laptop 5 to 9 times (not 10+), and a phone 30+ times (not 50+). The review has been updated to reflect these changes.