Published Sunday August 24, 2014:  Updated January 7, 2017

The JuiceBox EV Charging Station

A level-2 charging station is essentially a smart switch that relays AC power from the electric grid to an electric vehicle's on-board battery charger. It has lots of fancy checks and fail-safes that it goes through before it deems it is safe to engage power to the car. It is then up to the battery charger on the electric vehicle to convert power from AC to DC and charge up the battery.  The charging station also senses malfunctions and will shut off power before an electrical accident can happen. 

As with any new technology, the first products to market tend to be very expensive. Charging stations for electric vehicles have been no different. They started out in the $3000 to $5000 range. After a few years they came down into the $2000 range. As of August 2014, they are in the $600-$800 range, with fancier ones and name-brand models still costing upwards of $2000. Many of these are only designed to supply 15 Amps at 240 VAC (3600 watts)  and the more expensive ones are rated to supply upwards of 30 Amps of power (7200 watts). 

Last year a small startup company called Electric Motor Werks started a crowd-funded project called JuiceBox where backers could get a 60 Amp, 15,000 watt L-2 charging station kit for only $99 (plus $10 shipping). 

Why pay $800 for a charging station that won’t even charge a Nissan Leaf at its fastest on-board charger’s rate, when for 1/5th the price, you can by a charging station that is capable of charging at 2.5x the onboard charger’s rate? How’s that for future expansion? 

Not wanting to miss out on a fantastic deal and support a brilliant, budding company, I put my money where my mouth is.  For $109, I became a financial backer. The Juicebox charging station kit arrived a few months later. 

What a difference having your own L-2 charger at home makes!

It is so easy to drive an EV farther now. My wife can now drive 80-100 miles in her Leaf in the morning, (to Ikea in Lehi and back gain), come home, plug in and take care of stuff for the rest of the morning. Then less than 4-hours later, take the car out again for another 80-100 mile jaunt around town that afternoon. 
Recently she even took her Juicebox with her in the Leaf for a 284 mile road trip to Bancroft, ID. Here in the oil and gas-obsessed badlands of Utah and Idaho, rapid charging stations are a rare site indeed. 

But since electricity is everywhere, being able to bring along your own L-2 charging station to plug into a NEMA 14-50 outlet makes longer road-trips in a Nissan Leaf possible. 

Are you as smart as a child? Then you too can quick charge at home. 

Driving an electric car and being able to quick charge at home, changes everything! For electric vehicle drivers, the notion of having to go to a gas station every time you are out of fuel, now seems needy, primitive and addicted. And actually paying for gasoline? Only to turn around and burn it? What a waste of money and mineralogical resources! 
Let's keep the oil in the ground or use it responsibly for something really meaningful, like building materials, textiles, or plastic car parts. 

I would much rather use the energy that was collected from our own PV solar array (FOR FREE) and drive around on that energy instead of burning fossil fuel, like tenant farmers burning fences.  Wouldn't you? 

Each morning I get in the car, it's always topped off with fuel. 

Someday our grandchildren will facepalm at the notion of our wasteful oil addictions. How embarrassing it will be for us. 

Building or Buying: 

Today, you can buy the JuiceBox fully assembled with cable and mounting bracket for $459. You can also add WiFi, power monitoring options and even an option to control it from your smart phone. 

The JuiceBox is based on the Arduino platform and is open source.

Electrical wiring requirements:

You can either hard wire the Juicebox or wire a NEMA 14-40 stove plug on it so it is more portable.  This will allow you to plug in and quick-charge at any location that has an accessible stove/dryer plug.  

While the built in battery charger in the Nissan Leaf has a near perfect power factor, 6600 watts is still a lot of continuous power. 

A 6600 watt Leaf charger, running on a 30 Amp circuit at 240 VAC (capable of 7200 watts) leaves little buffer.  This is a 109% overrating (7200/6600 = 1.09) for that circuit. The 2014 NEC (national electric code) requires a 125% overrating. 30 Amps and 10 AWG wire is close but technically you need a 40 amp breaker and 8 AWG copper wire to be completely legal and compliant. 

To max out the 15,000 watt JuiceBox charger and still meet the 125% overrating building code requirement, you would need an 80 amp breaker running 4 AWG wire. Also, make sure you don’t exceed the building's main breaker requirements.

To max out the onboard 10,000 watt Tesla Model S charger, you would need a 60 amp breaker using 6 AWG copper or 4 AWG aluminum wire.  

 Current Draw Wire Size Application
 15 Amp 14 AWG copper 
 20 Amp 12 AWG copper 
 30 Amp 10 AWG copper Nissan Leaf 3.6 kW charger
 40 Amp  8 AWG copper Nissan Leaf 6.6 kW charger
 50 Amp  6 AWG Cu, 4 AWG AL 
 60 Amp  6 AWG Cu, 4 AWG AL 
 80 Amp  4 AWG Cu or Al Max out Juicebox's capacity
 100 Amp 2 AWG Copper
 150 Amp 1/0 Copper or Al 
 200 Amp 2/0 Copper or Al 

Check out the other cool products coming out of Electric Motor Werks. Including a 24kW rapid DC charger for around $2800. WOW! 
I don’t believe a typical residential neighborhood infrastructure could support such sustained loads (especially if more than 1 home on the distribution transformer was rapid charging at the same time). But still, that is really cool. 

Next Article: Road Tax For EVs?