By UPDATE: Shortly after I published my initial review of the Yoshino solid state battery pack I bought for myself on Amazon, some people left comments that the company, TechInsights, had published a report saying it wasn’t solid state technology after they broke it down and tested it. However, when I looked at the free report TechInsights made available it raised more questions than it answered, so I reached out to them to start my own investigation (as well as to Yoshino for comment). I’m going to be publishing a full follow-up video of my investigation later, but didn’t want to leave the original video up without noting the issues.
To summarize the issue … TechInsights found a large amount of liquid inside the battery cell when they broke it open, which is the primary reason they concluded it’s not solid state (for obvious reasons). Yoshino is still standing behind their claim and points to their use of an IPC solid electrolyte. There are research papers into IPCs for solid state batteries that show it’s a viable path, but the amount of liquid that TechInsights found raises big questions about all of Yoshino’s claims. I shared those claims with the TechInsights team, so they’ve gone back to continue testing and fill in some of the gaps I raised in their initial report. I’m also working with a fellow YouTuber and friend of mine to do his own breakdown and analysis of the battery. As soon as that follow-up video is available, I’ll link to it here. It’s taking some time to pull all of this together because I want to make sure I have as much information and facts as possible for an informed answer. The original script is below.
If there’s any doubt that solid state batteries are actually here, well … here’s your proof. You can actually buy this for yourself, like I did, and get it delivered to your door in a day or two. No, solid state batteries aren’t everywhere and definitely not mass market yet, but they also aren’t vaporware and always five years away. Just like this Yoshino battery, which I’ll get into the details in just a second, there’s other solid state batteries right on the cusp of ending up in consumer electronics devices near you. But do these early versions live up to the hype? And who is this Yoshino battery really good for?
I published a video a few weeks back about the progress of solid state batteries and how they’re finally here. To say I got some pushback would be an understatement. I received comments like:
“Nuclear fusion has some company.” -rajivpokharel88
That’s really funny … not accurate, but funny. I guess I sparked quite a reaction. I really opened myself up to that point of view with how I talked about the latest developments. Everyone has a different definition of what a product being “here,” as in now, means. Does it mean it’s mass market or just that the first cells are shipping? It’s a bit of a charged topic. My focus on EVs didn’t help matters either.
Bottom line: I could have done a MUCH better job clearly defining what I meant by “here” and “now” in my video. I’ll amp up my clarity next time. But in a nutshell I was talking about how many companies are now producing solid state battery cells for actual use and/or testing by partners. We’re officially in the manufacturing ramp-up stage, so figuring out the chemistry and if it works is in the rear view mirror in some cases. That is a major milestone and a sign that the technology has hit a turning point—definitely a positive charge. However, I should have focused on a product that you can actually get your hands on today. Or to quote another comment on that video:
“Until I can order from Amazon it’s not even close; so PLEASE no SS information unless it’s in your possession.” -jamesbuckingham8073
Okay, here you go…
The Yoshino Power Station
I bought myself this Yoshino B330 solid state portable power station on Amazon and had it delivered to my house in two days. And to be clear, I have no relationship with Yoshino. This is the smallest version of their battery pack, which has 330W of continuous power and 241Wh of storage. They also have versions that scale all the way up to their B4000, which has 4,000W of continuous power and 2,611Wh of storage capacity.
In general, the reason you might want a small battery like the B330 is for going camping or reserving emergency power to charge up your phone or laptop in a blackout. The larger batteries are also great for those same uses, but are even better for running power tools at a worksite that doesn’t have power available, backing up more substantial appliances in a blackout, or even getting your entire home back online.
The little guy I have right here weighs in at 9.9 lbs and can charge in a couple of hours. What’s nice to see on even a small unit like this is that you can charge through one of three ways: 1) the DC input on the back, 2) solar panels, and 3) USB-C power delivery on the front. You can also tandem these up to speed up the charging, so you can be charging through both the USB-C and DC or solar input on the back at the same time. There’s a couple of DC output terminals on the front, as well as 2 AC outlets, 2 USB-A, and 2 USB-C ports.
The main focus of Yoshino for this design is meant for on-the-go power, like as an emergency backup or for use during camping trips, so there’s a LED light bar that can act as a light source. It’s not the brightest light in the world, but in a pinch it’s a nice thing to have.
And much like other battery packs in this type of product, you can also connect to it through an app via Bluetooth or wifi. This allows you to install firmware updates and to control it remotely. It’s not an earth shattering app, but is well designed and easy to navigate. It shows you what ports are currently active, the power draw, and how much time is left given the current usage. You can also monitor its charging status, which can be handy when you’ve got some solar panels plugged in.
So what’s inside this thing? Well, it’s a solid state cell that’s using an NCM (Nickel Cobalt Manganese) formula, which might sound similar to the widely used NMC (Nickel Manganese Cobalt). The reason for the different order of letters usually reflects the different ratios of those elements in the chemistry for the battery cathode. The big difference though is the use of a solid electrolyte versus a liquid or gel version. For Yoshino, they’re using an inorganic-polymer composite (IPC) for their electrolyte between the anode and cathode.
I reached out to Yoshino for some additional details on their battery and found out some interesting things. The team didn’t give me the exact formulation of their battery for obvious reasons, but did share details on the safety testing done by USA Energy Assurance Labs. Yoshino’s batteries were put through the paces for thermal runaway, nail penetrations, and short circuits, which are some of the big selling points of solid state batteries. This battery is substantially safer in those regards than a typical lithium ion battery with a liquid electrolyte.
But there’s also some of the other key attributes that set this battery apart that shouldn’t be a surprise if you’re familiar with solid state. They’re more energy dense, which means you can get the same power output and storage in a smaller package. They’re also better on the cycle life front too, so these should last longer than the competition that’s currently out there. But … how does that look in context?
Solid State Comparison
This is where we should compare the Yoshino battery to comparable power stations on the market. Some of the more popular brands out there are Bluetti, Anker, and EcoFlow, so let’s take a look at some of those.
Since I have the Yoshino B330, let’s compare it to similarly sized batteries: the EcoFlow RIVER 2, Bluetti EB3A, and Anker 522.
When you look at the price, it looks like it falls right in line with the competition. However, when you divide the cost of the unit by the Wh capacity, you start to see the difference. Yoshino is roughly $1.24/Wh, while the others chime in between $0.90 – $1.12/Wh. That means Yoshino’s battery, which is a first-gen product, comes in 11-37% more costly than the competition per Wh.
However, one of the key benefits of solid state is safety, longevity, and energy density, so how does it compare to the last one? Well, not so great for the model I’ve got. Yoshino is at 53.56Wh/kg, which is just slightly lower than Bluetti, but both EcoFlow and Anker have 73 and 76Wh/kg. What’s going on there? This made no sense to me, so I decided to expand my comparison to Yoshino’s largest battery, the B4000, to comparable batteries. I picked the EcoFlow DELTA Pro, the Bluetti AC300/B300 Combo, and Anker Solix F3800. This is where it got more perplexing.
Now, these models aren’t exactly an apples to apples comparison because of how they’re intended to be used. The Bluetti AC300/B300 combo is actually two separate boxes that you have to use together. It’s more meant for a permanent or semi-permanent installation, like whole-home backup or for an RV. In terms of power output and storage, though, it is comparable, which is why I picked it.
Money-wise, the numbers across the board landed in a very similar region, at least when non-sale prices are used for comparison. The Yoshino clocked in between 21-29% more expensive than the competitors. Not shocking, but the Wh/kg was very different. The Yoshino B4000 has 107Wh/kg vs. a range of 53-80Wh/kg. That makes the B4000 101% more energy-dense than the comparable Bluetti and 34% more energy-dense than the Ecoflow. This is more of what I was expecting to see when I dove into this comparison in the first place..
So why is the smaller battery, the one I’ve got, so behind in the comparison? My hunch was the physical design of the product and all the bells and whistles. Yoshino’s battery has a large and heavy metal handle that wraps around the entire box. EcoFlow’s River2, on the other hand, is all plastic with no light, which means there’s a weight savings from materials and components.
This hunch was confirmed when I reached out to Yoshino for more information. The team compromised some additional weight for the sake of additional functionality and aesthetics. Having one in hand, I can say it’s nice to pick up and looks great, but I’d personally have preferred a plastic casing to save some weight. However, those design choices become less impactful as you scale up the battery pack size, which is why we see the B4000 come out way ahead on that front. All of that raises the big question …
Why would you want this?
Well, it really comes down to your use case. Let’s start with the small battery packs. If you’re looking for the lightest weight and cheapest small battery pack to take with you on a trip, then you’re most likely looking at EcoFlow or Anker. However, if you’re looking for a battery that will last you an incredible timespan with the least degradation, is exceptionally safe, and can work in a wide range of temperatures without concern, then you’re probably looking at Yoshino. In this small size category though, it’s a tough sell.
So what about the larger battery format? Many of the same arguments hold true here, but this is where weight comes into play. If you need the largest battery that you can easily toss into the back of your truck or RV for a trip, even though the Yoshino B4000 costs more, it’s dramatically lighter weight. It’s half to one third the weight of the competition. Lugging a 53.6lb (24.3kg) battery on the back of your truck sounds way more appealing than a 100-130lb (57.7-60kg) battery. On top of that, the Yoshino will have a longer lifespan and is safer, too.
However, if you’re looking for a battery that could serve as a whole-home backup with a semi-permanent installation, Yoshino isn’t even on the table. Its current batteries are designed for that lifestyle type of brand: on-the-go uses, camping, and emergency backups.
There is an elephant in the room though. Many of the companies like Bluetti, Ecoflow, and Anker have massive sales and promotions that drive that cost even further down. If you pick up their batteries on sale, there’s no contest for the value you get. In that case, though, it’s important to remember one thing: this is the first-gen Yoshino battery. There’s no doubt they’re working on a second generation product that should be cheaper and more competitive on that front. The next crop of batteries should also be even more compelling on the energy density and performance front too.
That said, for a first-gen product, I thinkthe Yoshino holds up surprisingly well. As I always point out when looking at any product, it all comes down to your personal use case. That will dictate what features are more important to you and could make the slight increase in cost acceptable. I’m very impressed with the build quality and performance I saw in my testing … and I’m really eager to see where Yoshino goes from here.
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