Dakota Lithium PS2400 Review: A Blazing Fast Newcomer

8.0

Dakota Lithium PS2400

Like

• 
  Supremely fast charging
• 
  10ms switchover time
• 
  Beyond basic input-output connection options

Don’t like

• 
  Limited flexibility in solar charging
• 
  A little expensive

After six years of testing portable power stations for CNET, I can spot a good product pretty easily. Most of the time, the usual brands have established product lines you can count on, and it isn’t uncommon to identify poor performers from lesser brands by visual inspection alone (although we always fully test every unit). It is often the companies newest to the category that offer sub-par products early on. But they learn from the process and improve future versions. 

That being said, Dakota Lithium entered the space with a banger in the PS2400.

I’m not saying the Dakota Lithium PS2400 is perfect, but there’s a lot to like about it, and if they’re smart, Dakota Lithium will use this as an incredible foundation to build upon. Let’s break down the pros and cons.

Dakota Lithium PS2400: The good

I’ll start with the headline. This thing charges faster than any other power station you’re likely to get your hands on. It’s up to you to decide exactly how important that spec is, but most people seem to rank fast-charging near the top of their wishlists for energy-related products. How fast exactly? We saw an overall charge rate of 26.76 watt-hours per minute. 

In our charge tests, we don’t just rank units in order of completed charge time, since the capacities of the power stations we test range from 200 watt-hours up to 10kWh. Obviously the smaller units would finish much sooner. But, we average the time it takes to charge with the stated capacity of each battery. This gives us an average amount of watt-hour-per-minute you can expect when charging the product. Check out the other power stations and how we test them here.

One of the things I like most about this version of the test is the “above 80” aspect of battery charging. Lithium batteries tend to charge more slowly after they’ve reached 80%. We’ve seen some dramatic changes in charge times on either side of the 80% line in some products over the years, sometimes as much as 50% of charge time being spent on that last 20% of charge. The PS2400 only varied by approximately 2 watt-hour per minute on either side of the 80% line, which is a major contributor to its fastest placement, and speaks as well to the product’s design and battery management system (BMS). 

Another strength of the PS2400 is its switchover time. That is, how long it takes to switch from grid power (aka, ‘the wall’) to the battery backup when being used as an uninterruptible power supply. A few years ago, it was fairly standard for this spec to sit around 20 milliseconds for most products in this category, which is pretty good. However, you generally want a switchover time of 12ms or less in situations where the UPS is being used for critical systems like medical support equipment. The PS2400 sports a switchover time of 10ms, which is likely to become the norm over the next couple of years.

I do also like that the PS2400 offers a twist lock 30-amp outlet in addition to the traditional 20-amp receptacles. As a frequent user of high-powered devices (usually tools) in areas where ample power is not always available, this is a feature that has definitely guided my own purchasing decisions in the past. You also can’t overlook Dakota Lithium’s 11-year warranty.

Dakota Lithium PS2400: The bad

I won’t say there’s anything I absolutely hate about this unit, but I do have suggestions for improvement. First on the list: the input and output covers. 

These little doors are designed to be more effective at keeping out dust, debris, moisture — I assume. That doesn’t keep them from being annoying sometimes. I find they occasionally get in my way and cause some fumbling around. I’m not sure if I can tell you what the perfect solution is — the balance between protection and user interface — but I know this isn’t it.

A bit of a “good” mixed in here, but the PS2400 can be linked with a second unit to double its overall capacity (that’s good, if not great). But even at 2kW, I’d like to see a higher ceiling for solar charging. The spec is listed at an 800-watt maximum input, but most other units in this class are sporting between 1,200 and 1,600 watts of solar input, especially for the ones that can be linked together to increase capacity.

The pricing for the Dakota Lithium PS 2400 is OK. It isn’t unreasonable, but at $2,400, it is near the top of the scale on similarly sized units. I’d like to see this just a touch lower to make it more competitive in the marketplace and an easier choice for consumers to make, especially since it’s one of the first entries into this category from Dakota Lithium

Dakota Lithium PS2400: The bottom line

I really like this unit and I think you should buy it. If you’ve read this far then I’m guessing that’s what you’re looking for. If this ticks your boxes, don’t hesitate. 

From a broader view, keep your eyes on Dakota Lithium. I think they’re in a great place to build a supremely competitive product line in this space, joining the likes of other long-timers such as Jackery, Anker, EcoFlow and others.

How we test portable power stations

Currently, we look at two main performance metrics for portable power stations: charge time and discharge capacity. Every company that sells portable power stations provides the expected number of watt-hours its products are supposed to last. For the Jackery Explorer 240, that’s 240 watt-hours; for the Ecoflow River Max, it’s 576 watt-hours. Bluetti AC200P claims 2,000 watt-hours. 

That means if you run a device with a 1-watt output on the Jackery Explorer 240, it should last for about 240 hours. You’d get 576 hours from the Ecoflow model and an impressive 2,000 hours using the Bluetti generator. That would last you almost three months. For reference, a USB-C iPhone charger draws up to 18 watts, a 3-quart Instant Pot draws 700 watts and a standard microwave draws around 600 to 1,200 watts, depending on the model. How accurate are those figures?

Usable capacity

A power station’s capacity should be a no-brainer. You should be able to look at a device’s rated watt-hours and purchase accordingly based on your needs. Generally, you can do that. I’ve found that you typically won’t see the entire capacity rating as usable power. 

Lots of factors can affect this, and most of them center on how the manufacturer chooses to build their units’ internals to manage their charged capacity. There is some (usually negligible) amount of power that goes to fuel the various indicator lights and readable LED panels on the units. Some of the larger units even have their own operating systems, so it’s almost like powering an additional mini PC on the inside. Other units can have power-saving features where they reduce outgoing bulk power as they come close to depleting their charge.

To run our capacity tests, we connect several 10,000-lumen LED work lights, rated at 110 watts, to each unit. (The number of work lights is based on the overall watt-hour rating of the unit under test, or UUT.) We record the outgoing voltage and wattage using external measurement instruments or the UUT’s own measurements if available. Once we have this data, we can leverage the calculations into a dizzying array of information about the UUT’s performance. The main piece of information we look at here is the observed capacity, based on our measurements, compared to the UUT’s stated capacity.

Here’s that mass of data in a nifty chart, where longer bars indicate power stations with greater percentages of battery capacity that you can put to use.

In every case, that percentage ends up at less than 100%. Most manufacturers say you should calculate expected usage at 85% of the stated capacity. Two of our smaller units (green bars) both clocked 98% capacity — the Jackery Explorer 240 and the Togo 350. Generally speaking, the midsize units (blue bars) didn’t fare well. The large-size units (yellow bars) did better, with the Bluetti AC200P scoring highest at almost 96%. As for our extra-large units (purple bars), the 3,600Wh EcoFlow Delta Pro fared the best, with a usable capacity rating of just over 92%. Behind it, Oupes, Mango, Yoshino and Dabbsson each had extra-large power stations (at least 2,200Wh) that scored above that 85% benchmark for usable capacity.

A quick word on our math here. If you blindly accept both a unit’s stated capacity and our work light wattage rating of 110 watts, the numbers look very different. For example, we will take the GoSun PowerBank 1100 (to make the math easier) and attach four of the 110-watt lights. That load rating is now 440 watts and the GoSun’s capacity of 1,100 divided by 440 is 2.5. We would expect to see 2.5 hours of usage. The actual run time for this unit was 2 hours, 50 minutes — 113% capacity. Sounds great, Right? We’re missing some key factors. Without going into a long(er) explanation of how to more accurately measure power, the fact that this unit has an output of 110 volts AC (compared with 120VAC) and the actual output wattage to the four lights is 352 watts, our real expected run time is 3 hours, 8 minutes, which drops the capacity rating to 90%.

Charge time

Charging performance can be nearly as important as knowing your capacity stats. It helps to know how long your device will take to charge, especially if you’re crunched for time or need to be able to charge quickly for whatever reason. Will it take 1 hour or 2? What about 10? Or 12? (That’s an actual number from our tests.)

We report three data points for charging performance. Each unit is plugged in for AC charging and we record how long it takes to reach 50%, 80% and 100% charge. Half full is probably the least amount of power you’re going to want, especially from the smaller units. 80% is the “magic number” for many rechargeable batteries. 

Here’s a simple-ish way to illustrate it: Imagine a swimming pool with room for 100 people, each person representing 1% of the total space. When you first start charging, and that first person dives in, you don’t have much to worry about. You’re not going to run into anyone else, so dive, splash around, whatever you want. As we add people, it gets a bit more crowded and complicated. You’ve got less room for people. Once you have 80 people in the pool, that next person is going to take a few extra seconds to choose their entry without causing any issues rather than just jumping and hoping no one is in the way.

Each manufacturer deals with this purposeful slow-down in its own way, so you won’t see the same performance changes from one manufacturer to the next. True to the analogy, person No. 100 into the pool can sometimes be very slow, taking several times longer to get in than any of his predecessors.

Take a look at the full charge test results below. Charge times are listed in hours, so shorter bars indicate power stations that charge faster. In many cases, you can see how the charge rate is fairly constant between 0% and 50% (red) and from 50% to 80% (yellow), before slowing down from 80% to 100% (green).