Featured Electric Car Product: JuiceBox Pro 40 EVSE


JB Post21

The latest addition to my EVSE obsession collection is the JuiceBox Pro 40, seen here charging my i3

One of the first things many first time electric car owners ask once they’ve bought (or are about to buy) their new car is what home charging solution should they choose. Other than asking for advice on specific plug-in cars, it’s the most popular question I get from readers here.

Luckily, there are some really good choices on the market now, and the prices for home EVSEs are considerably less than they were when I first started driving electric in 2009. Back then, the only level 2 home EVSEs that I would recommend were from Clipper Creek. Clipper Creek still makes very good products, and I still recommend them, but the competition is getting better all of the time, and one company in particular, eMotorWerks has been gaining momentum in this competitive market.

*Editor’s Note: This post also appears on Tom’s blog. Check it out here.

*Additional Note: eMotorWerks provided Tom with the JuiceBox Pro 40 for testing purposes only. 

Before I get into the review, I’d first like to explain some basic EV charging levels and terminology. This applies to charging in North America, as electric supply is different for most European countries.

EVSE: Electric Vehicle Supply Equipment. These are quite often called “chargers” or “charging stations.” That really isn’t the correct terminology though, because they don’t actually charge the car. They really just safely supply the electricity from the power source to the vehicle. The actual charging equipment is built into the electric cars. Some EVSEs are portable, while others are hard wired and permanently installed.

Level 1: Every electric car sold or leased in the US that isn’t a Tesla comes with a Level 1 portable EVSE. Some manufacturers, like BMW, call it an “occasional use charger.” Level 1 EVSEs can be plugged into a simple 120 volt household outlet and typically charge at 6, 8 or 12 amps. Tesla doesn’t bother with Level 1, 120 volt EVSEs because their vehicles have such large batteries that they would take very long to slow charge on 120 volts. For that reason, every Tesla comes standard with a portable 240 volt EVSE for more robust charging at home or on the road.

Level 2: Level 2 EVSEs charge at 240 volts and most of the time are permanently installed in a garage or public parking lot. However, recently some manufacturers have been selling portable 240 volt EVSEs, allowing the owner the flexibility of using the equipment at home as well as on the road, provided they can find a 240 volt outlet that they can plug into. The JuiceBox Pro 40 which I’ll be reviewing here today is one of those newer units, and comes with a NEMA 14-50 plug instead of requiring the owner to hard wire it to their home.

DCQC / DCFC: DC Quick Charge or DC Fast Charge. DC fast charge allows rapid charging of electric vehicles, enabling long distance travel with little inconvenience. DC Quick Charge stations can charge many EVs up to 80% full in about 30 minutes, but are not something an individual would buy for home use because of the cost and required 480 volt electric supply. These units are very expensive and are only just beginning to really proliferate. Unlike Level 1 and 2 charging, there are multiple connectors used by different manufacturers, as a single standard hasn’t been established yet.

Some people live fine with their EV, charging solely with the supplied 120 volt portable EVSE. However most owners will prefer using a 240 volt EVSE, so that they can charge much faster, enabling the vehicle to be driven more miles if needed. For example, a basic 120 volt EVSE will replenish about 4 to 5 miles of range per hour, while a standard, 30 amp 240 volt unit will add 20 to 30 miles of range per hour to the typical EV. That can make the difference of being able to use the car or not on some days.

JuiceBox Pro 40 EVSE

JuiceBox Pro 40 EVSE

I think I’ve charged my EVs on every brand of EVSE on the market today, and I have a host of EVSEs in the garage at my house which I use for various testing and when I have visitors that also have cars that plug in. I had been reading a lot about how eMotorWerks has been expanding lately, and how they recently sold their 3,500th JuiceBox EVSE. So when the opportunity came for me to test out the latest offering from eMotorWerks, the JuiceBox Pro 40, I happily accepted. I want to make it clear I did receive the EVSE free of charge, however I wasn’t paid to do the review, and there were no conditions or promises on what I would write. In other words, if I didn’t like it, I would say so, or perhaps not even write a review.

First, I’d like to point out the JuiceBox Pro 40 can deliver up to 40 amps of power. The vast majority of Level 2 EVSEs currently on the market are limited to delivering 30 amps of power.

There are a few other companies like Clipper Creek for instance, that do offer a 40 amp EVSE, but for the most part, the industry norm is 30 amps and even less in many cases. When buying any EVSE, make sure you find out what the maximum power the unit can deliver before purchasing it. I know more than one EV owner who bought an EVSE and didn’t know it could only deliver 16 or 20 amps until they installed it.

Why does 40 amps matter as compared to 30 amps? Well, for most EVs today, it doesn’t. Only Tesla makes on board charging equipment that can accept more than 30 amps from a level 2 source, however that is going to change. I like to recommend future-proofing your garage, and if you’re investing in a home charging solution which you may be using for ten or more years, why limit the charging supply to today’s norm when home charging will only get faster as EV adoption increases?

If your home has the capacity to add a dedicated 50 amp circuit (a 50 amp circuit is required for a continuous 40 amp load), then I say pay the few extra dollars today so you don’t have to go back and upgrade in the future.

Voltage, amperage and kW draw displayed

Voltage, amperage and kW draw displayed

Switch between Amperage or kW draw screens

Switch between Amperage or kW draw screens

The feature I love the most about the JuiceBox Pro 40 is that is has built in WiFi and connects to eMotorWerks servers. This allows for real time charging monitoring which includes voltage and current measurement accurate to 0.2%. This is the only EVSE I know of currently available which allows you to monitor this kind of charging data. I know a lot of EV owners, and one of the things that keeps coming up is people asking how they can find out what the car is drawing during charging. ChargePoint allows the current measurement to be viewed on their app if you are charging on one of their networked EVSEs, and they used to offer a home EVSE (CT-500) which allowed the same, but that has been discontinued.

Having the ability to monitor your vehicle’s electric draw is particularly useful to BMW i3 owners like myself. The original i3s shipped with faulty onboard chargers, causing many of them to fail. This resulted in the car charging at half the speed than it was supposed to (15 amps instead of 30 amps).

To make matters worse, while BMW engineered a new onboard charger, the dealers were instructed to de-rate the i3’s current charging capabilities to about 24 amps, in an effort to keep the charger from failing. Many i3 owners didn’t know if their car was de-rated, if their charger had failed or if they were charging at the full 30 amp rate. Without a way to really measure the energy the car was accepting, many were left in the dark for a few months while BMW built and installed the new, modified onboard chargers. If they had an EVSE that had the capability of displaying the rate the car was charging at, they would never have to wonder what the car was capable of drawing since they could simply look at the app when they plugged in.

If you’re wondering if you can mount and use the JuiceBox outdoors, this video demonstration should satisfy any concern you have.

The connector has a cover

The connector has a cover

As mentioned above, the JuiceBox Pro 40 doesn’t need to be hardwired. Instead, it comes with a NEMA 14-50 connector. This allows the owner to take the EVSE with them, all they need to do is find a NEMA 14-50 receptacle and they can plug in. The 14-50 outlet is commonly used by RVs and thousands of RV parks across the country have 14-50 receptacles where you can plug in on the road if needed.

But in my opinion, the real beauty of having a portable, plug-in EVSE is you can install 14-50 receptacles in places like your parents or friends home, or even work, and take the EVSE with you and charge at your destination. This is much less expensive than installing EVSEs in locations you may need to occasionally charge at. The JuiceBox is small and light enough to take with you when needed. You can see this on the photo above compared to the other EVSEs I have mounted on my garage wall. The connector also has a rubber cap if you do mount or use it outdoors.

The app is very easy to set up, and should take you less than ten minutes to complete. There is also a web portal which you can log into for past history charging info (it stores data from your last 20 charging sessions) and soon you’ll be able to set up notifications from the site. eMotorWerks also offers 60 amp, as well as 30 amp EVSEs, with and without WiFi connectivity.

The JuiceBox Pro 40 with WiFi currently costs $599.00 which is $100 more than the basic JuiceBox 40. Personally, the WiFi feature is well worth the upcharge and I highly recommend getting it. You’ll really appreciate the ability to look at your past charging sessions and energy consumption and it definitely helps you to see exactly how much energy your EV car uses because you’ll have a true “wall to wheels” measurement, which includes charging losses.

The in-car energy use calculators don’t include charging losses or the energy used from battery or cabin preconditioning while charging, but this does. The difference can be significant, especially during the winter months when the battery may needs to be warmed while charging. The JuiceBox Pro 40 comes with a 24 foot cable which is a little longer than most standard EVSE cables. The extra few feet of cable can make the difference of having to back into your garage or pull straight in, and possibly allow you to park on either side of the garage in any position and still have enough cable to plug in.

Don't let the plain, metal box look fool you. This is a seriously good EVSE

Don’t let the plain, metal box look fool you. This is a seriously good EVSE

The EVSE market is getting better all the time. The products available today are more powerful, lighter, some are portable and overall less expensive than the products available only a few years ago, and this is welcome news to EV owners. eMotor Werks is a relative new comer to the field of EVSE manufacturers, which is mostly dominated by larger, well established companies.

However, the people there seem to understand what the EV owner is looking for in an EVSE, and they have delivered it with the JuiceBox Pro 40, which is why I recommend it. The price is right, the size is right, it’s powerful and portable. About the only thing you can criticize is the plain-looking metal case which houses the electronics. If that really bothers you, you can always paint it, or apply a vinyl wrap or sticker to add some pizzazz. 🙂

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32 Comments on "Featured Electric Car Product: JuiceBox Pro 40 EVSE"

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Great review Tom of the best bang for the buck EVSE. Now you’re all set to plug in your future Rav4 EV purchase 😉

Nice commercial for the juice box. I’ve talked to the owner of the company at various times, but I’m a bit queasy about the robustness of the unit. Let’s take the issues one at a time: 1). “Outdoor Construction”: Looks much more like Nema 1, than Nema 3R equipment, which would be required by any electrical inspector. Only ‘listed’ equipment will pass any electrical inspection, and, I would be very surprised if this equipment had a Nema designation , or even an Underwriter’s Laboratories Listing. UL is a mere shadow of its former self (my Schneider which, unmodified, would overheat after 8 hours), was UL listed and supposedly that HORRID (ON THE) Blink thing (- the old one, not the NEW BLINK – which is essentially the same product as the rebranded Chinese Bosch units, which are perfectly fine). But to be used outside, the unit would have to have a minimum of a UL listing and a minimum of a 3R rating. That STUNT about freezing it in a block of ice is the same nonsense that Sunoco (Sun Oil Company) used to pull 40 years ago by freezing a CAR IN ICE and it started (!) News to… Read more »

“News to the unitiated: Ice is HOT. 32 degrees fahrenheit is NEVER seen around here in winter time”

Bill, you need to be initiated 🙂 Ice, like any solid, can be any temperature below its melting point, in this case, 32º F. So ice on a cold winter day can be the same temperature as the cold air surrounding it.

That’s just plain dumb. Ice has half the specific heat of water, and will quickly rise to 32 degrees fahrenheit in a bucket of water (sensible change) and commence the change of state (Latent change to water) (2.108 compared to 4.187 kj/kg per deg centigrade if you want the figures in metric).

While everyone has different preferences and priorities, it’s nice to have so many more choices and much more attractive price points than we did just a few years ago. The most affordable EVSE for my car, when I first started to drive an EV, was over $1,000. Now, we have much less expensive choices, and also better products. I have a few thoughts in response to Bill, as some of his assumptions seem to be a bit off-base. I wanted to focus on facts for the moment, and not necessarily entertain a debate, so please bear with me. Let’s take the issues one at a time: 1). “Outdoor Construction”: Looks much more like Nema 1, than Nema 3R equipment, which would be required by any electrical inspector. The enclosure is built by Hammond Manufacturing, and is indeed NEMA 4 rated (NEMA 4 is a higher rating than 3R and will withstand ‘water jets from any direction’ vs ‘rain from the top’ in case of 3R). It is watertight, die-cast aluminum, and gasketed. All connections into or out of the enclosure are sealed with either a sealant, and/or a watertight cord-to-box strain relief. 2) Only ‘listed’ equipment will pass any electrical… Read more »

See my response to Tom below. I, and several posters here, remain unconvinced.
Tom at least, says he will investigate.

So are your products UL Listed or do you have other official ratings/certifications?

Over a year ago I was told the same thing, that of continued testing.

Why are you selling products prior to completion of testing? Why aren’t these being listed?

What is the Hammond box number, and what are the manufacturer/part numbers of the cord clamps which also must be NEMA 4 compatible?

Ok, be sure to hide the Juice box before the electrical inspector gets there then.

As regards 50,000 Tesla UMC’s if you are refering to the Roadster ones for $1500 those all burned out multiple times per roadster owner. Tesla techs carried many around in their service vehicles since they were so failure prone.

If you are talking about S umc, it was designed by an incompetant. Later on, when there were questions about 2 garage fires, Tesla put in a software kludge to lower the current, and then in addition, later on thermally fused the plug. No surprise to me it is not UL listed.

Bill – can you tell me who the Chinese units like Bosch come from? Thx.

What the heck? Four different chargers? Why?

“If you’re wondering if you can mount and use the JuiceBox outdoors, this video demonstration should satisfy any concern you have.”

Thanks for the article, Tom! And thanks for mentioning the possibility of an outdoor installation.

I get tired of so many people saying that you can’t charge a PEV at home if you don’t have a garage. Assuming the charger is outdoor rated, you can install it in a carport, on the side of the house, or on a post in the driveway, or even (GASP!) on a post at curbside.

Having a garage is nice if you own a PEV, but it’s not a requirement. Only a reserved parking place is required.

I’ve had two “standard” JBs installed outdoors for nearly a year. No trouble with them.

I agree with Bill. I bought an early version of this Juicebox and was thoughly unimpressed with the build quality, robustness, components, and ability to survive day in, day out. This is the same company that sold (and still sells?) a Y adapter to allow you to plug two 120V circuits together to form a 240V outlet, but didn’t put in ANY safety features, guaranteeing a shock hazard when used with an EVSE.

I’d like to add that it is very easy to see how much juice your EV is drawing while charging even if the car doesnt tell you. I have a short cord about 6 feet with a Nema 14-50 plug on one end and a Nema 14-50 receptacle on the other end. In the middle is a small round old style meter socket with a new style digital meter installed. This is the same thing that would be on the side of your house. It was very easy to make and cheap. You can get a meter on ebay. Its also alot more compact than it sounds. It tells me volts, amps, and Kwh used. It can be used with any of my three different evses ( yes im addicted like Tom). All of us that compete in Penn State’s 21st Century Automotive Challenge have them and use them every year to check kwh usage. All the Tour de Sol teams had them as well. I wish i could post a picture. Tom, let me know if you want a picture of it or instructions on how to build one or where to find the parts. It would look great… Read more »

I haven’t seen such meters that read amps. Can you point me to an example?

I’m also looking for a simple “lifetime kWh” meter like this.

I bought a related product from EMW last year and had an issue with it. I emailed them and didn’t get a response, so I emailed again. Still no response. OK, I’ll call them. Just voice mail as no one ever answered. Left a couple messages. Left a couple more. Emailed a few more times. Phoned a few more times. Never heard back from them. I was stunned. It was a minor issue with a display they sell, and could have been resolved by answering a couple of questions. So now it just sits in a box. Waste of money. I’d really love to see them succeed, and hope others have a better experience than mine.

I wanted to let you know that I am now helping out at eMotorWerks with support. I actually handle installation, PEV Pilot, and customer relations. I apologize if you didn’t hear back, and there are no excuses, but if i can help you now, please reach out to me. jb-support@emotorwerks.com

Sorry, but can’t *we* (EVers) at least get some standard nomenclature for EV charging settled? You talk of ‘fast’, ‘quick’ and ‘rapid’ and no-one – even longtime Evers – are any the wiser what you are talking about!

In Europe there are 3 generally accepted levels of charging:- ‘slow’, ‘fast’ and ‘rapid’ (perhaps they should all start with capital letters). My proposal is that we use these adjectives and that they mean:-

Slow 20kW

One day we may need another, higher one (Cosmic?!) but for now that should do! MW

I have several JuiceBoxes and have found them useful. EMW responses to trouble reports have been between sluggish and absent, however. I found the display on the premium units to be nearly useless. The keyfob wireless communication to the premium version can be troublesome. I found the wifi to be almost useless because of the difficulty connecting them to an access point. I carry a JB (not premium) with me on Tesla trips; it usually allows me to charge at up to about 45 amps out of a 14-50 RV type outlet.

eMW has an enhanced, UL approved, JB design currently going through, and almost completed, “NTRL” certification.

Underwriter’s Laboratories, even back in the day when they were really a GOOD service, never APPROVED anything.

They LIST equipment which they have found to be MINIMALLY safe. That’s it.

Yes, “UL approved” is not a valid term, and it should not be used when referring to a UL Listed, UL Recognized or UL Classified product.

There are a number of requirements and guidelines that should be followed to accurately communicate a product’s UL certification.

There is a very useful reference on the Underwriters Laboratories’ website:


The meter i use to track kwh and amps and such is the same meter that is installed on the side of your house as i stated. You cant easily buy one from Home Depot or Lowes but you can buy them on ebay usually very cheaply. I have a newer digital one.

EMW accuses me of having views ‘A bit off base’, however they will only answer the particular bullet points where they think they HAVE an answer and won’t address the ones where they don’t.

I don’t begrudge them making a buck, which I’d assume is in the $millions by now.

My problem is why would InsideEvs advance equipment that an Insurance Company would have issues with? A conservative approach would be only advertising equipment which has been listed and certified – that would solve namecalling games later when someone had problems and decided to yell at InsideEvs because of the overly glowing reviews given them.

I have never owned a Clipper Creek product, as an example, but then again, I have never heard of anyone having any systemic problem with their products. Whether some of them are overpriced is another question, but some of them are VERY low priced and great values. So the times when InsideEvs has promoted CC I have no problem with, since apparently readers will not have the problems some of the other posters have had just in this article.

Bill, you raised a number of good questions and valid concerns. Safety ratings and certifications exist for a reason, and those manufacturers that chose to market products without a safety certificate from an OSHA-recognized test lab will suffer the consequences. They will not be able to qualify their equipment for any type of official program. Charging stations without a safety rating will not qualify for utility subsidies, such as the ones offered by LADWP or Puget Sound Energy. Many consumers will shy away as well, and last but not least, competitors will pick up on this fact, and will leverage it as well. That said, it’s not illegal to sell electric equipment without safety certification in the United States. The test process can be lengthy and expensive, which is why small-volume and less established manufacturers choose to do without it. This does not necessarily mean that the equipment is less safe, and it would behoove the manufacturer to design it the best they can, since product liability laws will always be in effect, regardless of insurance policies or coverage. Obviously, not having a safety certificate will make it difficult for consumer to assess how safe or unsafe a particular device… Read more »
They’ll never admit it of course, but I think EMW is trying to clean up their act a bit, what with hiring an ‘ombudsman’ to get back to people whom they never called back/or ignored. They may be finally trying to get stuff out that is somewhat more substantial, but I don’t like stuff that isn’t fused even if I’m told “nothing can ever go wrong”. Fisker found this out with several fiskers catching fire since they never saw the sense in fusing the electric cooling fan. I don’t respect UL as much as I have in decades past, for several reasons which I won’t go into here (I feel the whole outfit is politically compromized). Years ago, If a device had a UL listing (they didn’t have those ‘recognized’ and ‘categorized’ subdivisions back then – that just confuses the issue in my view.) – you knew it would not catch fire, or run in a deleterious manner. The kicker was if something was not UL listed you would find obvious trouble. Now, Schneider and the Old Blink things which were overheating and trouble prone (and unsafe in my opinion), get the UL recognized nonsense, when decades ago the things… Read more »

Bill, yes, that’s correct. I believe that the JuiceBox design UL signed off on during the certification process contained an internal fuse or breaker. So from this perspective, you seem to a valid point once again. I believe that the desire to get UL certified triggered a re-thinking and several design changes which should be reflected in the upcoming UL-certified product. Hopefully, it’s not too far away now.

Hey Tom
The company was acquired by Enel, it would be good if you could update the review accordingly. You can check this site to confirm. https://reviewertips.com/juicebox-pro-40-review/

That’s true. This charger now belongs to Enel. I’d also suggest Tom to update the review.