Base JuiceBox Kit Assembly Manual - Legacy help

Kris Kluzak -

Electric Motor Werks JuiceBox - an Open Source 15kW 60A Level 2 EV Charging Station

V8.9 / V8.10 Base Kit Build Manual

Last Updated: October 29, 2014

The latest full version of all materials is always available from:

Direct link to this manual:

We now also have a Video Manual for Base Edition Kit Assembly in HD! Enjoy!


Dear Fellow EV Enthusiast,

Congratulations on purchasing the 15kW 60A Open Source JuiceBox Kit!

By assembling this device yourself, you will understand how EV charging systems work and will enjoy your EV much more – knowing that you built your charging ‘infrastructure’ yourself!

You will also learn a good bit about open-source hardware - the exciting revolution that is happening in the hardware world today. By moving power to make things from big corporations to people like you, we will all innovate faster and make things better for all to enjoy!

Finally, you will be able to easily adapt the JuiceBox to your liking – all the designs are completely open source and the latest versions are always available.

Thank you again for joining us on this journey to more sustainable and fun transportation!

A special thank you goes to all our KickStarter backers! Without you, this product would not exist. If you are not our KickStarter backer, check out our original KS campaign at - it has a lot of good info on the product, our philosophy and what we are trying to do.

JuiceBox is not just another EVSE – it’s a completely flexible EV charging platform.

Go Electric!


Valery Miftakhov, Founder, Electric Motor Werks, Inc. – on behalf of our great team!



Any questions / issues / suggestions on kit assembly - contact [email protected]. Dorian - our awesome Production Engineer - will help you sort things out!

CAUTION! This is a High-Voltage, High-Power design.


It is NOT your average weekend electronics project so do NOT treat it like one.


If not approached with caution and extreme attention to detail, this project can kill you, burn your house, etc.


By starting this project, you expressly agree that neither Electric Motor Werks nor any of its directors, employees, or partners are liable for any damage that may result from this project and associated activities.


Furthermore, there is no explicit or implicit warranty or guarantee of applicability for any particular purpose. For JuiceBox Kits, E Motor Werks will only warranty the parts to be free from manufacturing defects for 1 (one) year from the date of purchase. For the assembled units, we will warranty the parts and complete assembly to be free from manufacturing defects for 1 (one) year from the date of purchase.


WARNING:   This document describes circuitry that is directly connected to the AC mains, and contact with any part of the circuit may result in death or serious injury. By reading past this point, you explicitly accept all responsibility for any such death or injury, and hold Electric Motor Werks, Inc. harmless against litigation or prosecution even if errors or omissions in this warning or the document itself contribute in any way to death or injury. All mains wiring should be performed by suitably qualified persons, and it may be an offense in your country to perform such wiring unless so qualified


Table Of Contents


Founders' Message




What am I building?


Specifications and Features

Build support

Part 0. Before you start

Part 1. Project description

Overall build reference

Part 2.A. Base Kit Contents

Part 2.C. Mounting Components and Wiring

Part 2.D. Connecting the cables

Part 3. Full Power Test / First Connection 

Part 4: Mounting your JuiceBox

Part 5: Using your JuiceBox

Base Unit:

WiFi operation (requires optional WiFi shield / module):

Links to Appendices at the end


What am I building?

JuiceBox is an Open Source 60A / 15kW Level 2 EV charging station costing ~5x lower than currently existing EVSEs of similar power (such as this).

This product was initially funded from a KickStarter campaign, receiving over 230% of the target funding amount from 300 backers in 30 days.

The device is a full-featured J1772 charging station and supplies up to 60A / 15kW to your J1772 vehicle (any production car sold today). This means up to 10x faster charging than from a regular household outlet (when wired to 240V supply, subject to charging speed limitations of the charger onboard of your EV). Generally, most of the newer EVs will experience at least 4-5x improvement by going to 240v with JuiceBox.

JuiceBox is built around an Arduino microcontroller (open source hardware platform) and is small enough to be used as a mobile charger (plug in at the RV park, friend's house's dryer outlet, etc). It is faster. It is Wi-Fi ready. It is more affordable and flexible than other EVSEs available on the market today. 

And the best thing is that it’s 100% Open Source!

EMotorWerks is making both the hardware and software open source. We expect many extensions to be made available in the future - developed by EMotorWerks or our JuiceBox developer community. You will be able to get the benefit of the great open source community around this product and get much more mileage out of your investment.

The Base version is designed with portability in mind; it’s dimensions (~11x7x3” box + cables) allow you to take it everywhere and enjoy up to 15kW of charging power. There is an automatic power derating for 120V outlets so you don't have to worry about overloading your house wiring in that unfortunate event when you have to resort to 120V charging.

Specifications and Features


  • Specifications:
  • Input voltage: 100-265V
  • Output power: 15kW / 60A
  • Whichever is smaller (i.e. at 208V supply, the JuiceBox allows 208*60 ~ 12.5kW)
  • Automatic power derating for 120V use – no need to reset the power limit when changing between 120V and 240V


          • 120V limit can be set to any current between 0 and 30A using R25 trimpot resistor (left stop=0A, right stop=30A)


  • Output type: J1772 AC
  • Size:
  • 11” x 7” x 3”
  • Environmental protection level: waterproof up to IP66 (when properly assembled and mounted)
  • Operating conditions
  • Outside temperature: -40C – +85C (-40F to 185F). The JuiceBox was proven to work outside of this range (which in turn is defined by the part with most restricted temp rating)
  • Humidity: up to 100% non-condensing
  • Features:
  • Multiple protection levels
  • GFCI (Ground Fault Circuit Interrupter) – ~20mA trip point – protect from electric shock (satisfies UL 2231-2 standard)
  • Standard J1772 power interlock – the output is not energized unless connected to a properly configured J1772 vehicle (diode on the pilot input)
  • Stuck relay protection – charging is disabled if internal relay is stuck closed
  • Variable output current limit – set via internal variable resistors (R20 for 240V, R25 for 120V)
  • Full hardware and software expansion potential
  • Open source hardware and software design
  • Hardware expansion through Arduino shields (UNO footprint provided on PCB)
  • Wi-FI ready
  • Firmware and hardware fully ready for an addition of the on-PCB module (based on a Roving Networks RN171-XV WiFi module)
  • Server-side applications are being developed to allow JuiceBox owners rich functionality to:


  • Automatic WPS-based WIFI configuration for a single button WiFi config


Build support


Just like with our other products (see for example), we are committed to getting our customers to the finish line on their builds! We have never abandoned a single customer and some of our build assistance threads run into hundreds of emails on our most complex products!

That said, we CANNOT offer phone support for any consumer purchases.

This is how we are able to maintain our low prices – phone support is extremely expensive and inefficient. It is a well-known fact that email resolution of a problem generally costs less than 20% of the cost of resolving the same problem over the phone. Email allows rapid routing of the issues to the right people who can best answer them. A lot of times, it is also faster to resolve things over email as it is more factual and structured means of communication. Finally, in email, there is always a record of what’s happening – which is always very useful for debugging issues.

So please EMAIL all JuiceBox questions to:



Finally, please understand that we assume that if you bought a KIT and not a fully assembled product, you know what you are doing. IF you have NEVER soldered anything before, it’s a BAD IDEA to buy a kit like this – see our CAUTION page above for details.

Part 0. Before you start


  • Required tools:


        1. Soldering setup
          1. A low-power soldering station with a relatively fine element
            1. 25W MINIMUM
            2. Something like this (what we use, $20 from Amazon)
          2. Electrical solder
            1. Make sure you never use plumbing solder as it may have conductive flux!
            2. Ideally 0.3-0.5mm thick
          3. If you need a refresher on your soldering skills, check
          4. Some quick tips
            1. Heat the leads, not solder – feed solder into the joint and let it melt & cover the entire joint before you remove the iron
            2. Especially follow this for ground plane connections – where the pin connects to wide copper areas – they tend to dissipate heat very quickly and you will have to hold your iron on them up to 2x longer
        2. Screwdrivers – small flat, medium Phillips
        3. Wire stripper & crimper
          1. For AWG 6 wire crimp, we recommend something like this (budget version) or this (the real deal)
        4. Small snips for wire / lead cutting
        5. Small pliers
        6. Clear Protective Goggles


  1. Recommended but not required tools
        1. Multi-meter with Capacitance / Resistance measurements – something like this ($25 on Amazon):  
          1. Also download / print the resistor color coding reference:



  • Helpful but not required tools


        1. Clamp meter with 100A+ AC current measurement capacity (something like this – ~$40 on Amazon)
        2. Infrared thermometer such as this (~$40 on Amazon)
        3. Scope with 1MHz bandwidth (or better)
          1. You can get one of these small units – they are open source and generally don’t have huge bandwidths / feature sets but will do the job just fine. In fact, we love these due to their portability – you can take this battery-powered unit anywhere!
          2. Or, if you think this is not your last project where scope would be helpful, take a look at Owon scopes on ebay or Amazon – those are great and relatively inexpensive devices that can be battery powered and small enough to be taken almost anywhere.



  • Assembly Tips


        1. Sequence of assembly is often important - follow instructions!
        2. Read instructions for the ENTIRE step before proceeding with the first instruction under that step
        3. Ideally, you should scan this entire doc before starting assembly
        4. To prevent shorts, make sure all unnecessary solder is cleaned from board



  • Education


        1. Wouldn’t it be nice to actually understand what you are building?
        2. You can pick up quite a bit by looking at a few good references
        3. For the real deal, purchase a full spec of J1772 protocol from SAE site

Part 1. Project description

Assuming you have all the tools available, and have good experience in electronic assembly, you should allow 60-90 minutes of component mounting and wiring for the base version.

This does not include the time required to make any adjustments you might need to make to your house’s electrical system to provide adequate / desired AC power to JuiceBox, or time required to troubleshoot assembly errors in the JuiceBox.

To provide AC power to the JuiceBox, we recommend you to have a standard 14-50R RV outlet installed near the location where you are planning to mount your JuiceBox. Any electrician should be able to do this with their eyes closed (figuratively speaking, of course ;-) and will not charge you arm and a leg (which they will likely do if you tell them you are installing a fancy EV Charging Station…)

You could also plug the JuiceBox into the 30A dryer outlets but the power will be limited to the outlet rating. Note that you still have to set the power limitation on the JuiceBox – it will NOT automatically sense the power capability of your circuit – all 240V sources will look the same to the internal circuitry.

Some stats on the project / complexity of assembly:

  1. Total electronic parts count: ~50 for Base version.
    1. All of these parts will be pre-installed on the PCB – you will get a complete PCB with all parts installed (“most” parts for Premium units)
  2. Total unique electronic part count: ~30 for Base
  3. Total other electric parts: ~20 (e.g., relay, power supply, wiring, etc)

Overall build reference:


Use the image below to get a general idea of relative placement of components. Specific details are described in the corresponding sections of this document.


FTDI programming cable is also not supplied anymore since the Arduino is now shipped fully programmed. You can always order your FTDI cable from us if you need to modify any part of the software or would like to monitor your Base JuiceBox output without WiFi installed – see our store at:

Base Unit with no J1772 or input cables installed (V8.7 board shown):


Part 2.A. Base Kit Contents


  • Die cast solid-body aluminum enclosure
    • M36 18-25 mm cable glands
    • Lid with foam gasket & bezel head fasteners
  • AC 100-240V to 5 - 15V DC power converter/supply
  • 80A rated power relay
  • A set of 18 gauge wiring for low-current connections
  • A bag with fasteners / hardware:
    • #8 button head machine screws, ½” (4)
    • #8-32 nylon zinc-plated locknut (3)
    • #8 lock washer (4)
    • #8 flat washer (6)
    • 16 - #6 cable lug (3 or 6)
      • 20 - #8 cable lug (3 or 0)
    • ⅛” ABS standoff (2)
  • Electric Motor Werks JuiceBox decal

Part 2.B. Prepare the Base enclosure


It is important that you attach and tighten down your glands now to secure glands to the enclosure - before parts which can be broken are mounted.

You MAY still need to do some minor enclosure prep related to MOUNTING your Base Edition JuiceBox. That is, unless you have purchased our Base JuiceBox mount, which requires no special assembly - just drill it into your wall and drop in your completed JuiceBox! If you have not, drilling mounting holes after everything has been mounted inside is NOT ideal (metal chips flying and all). So please think ahead on this one if you are planning to mount your JuiceBox permanently

Part 2.C. Mounting Components and Wiring


  1. Mount the Relay:
    1. Remove and discard the plastic cover on top of the relay. There is sufficient clearance between the relay terminals and the enclosure to prevent electrical contact. If you are still wary of accidental contact, you could simply apply some electrical tape on the enclosure lid above the relay, or trim away some material from the bottom lip of the plastic cover so it fits on the relay while the cover is on.
    2. Remove terminal screws from the common terminals (bottom terminals on the picture), coil terminals (next ones towards the top), and bottom contact terminals (next ones towards the top)
      1. The terminal screws are of different lengths so make sure you note which holes they go back into

    1. Orient relay with the input (common) terminals facing DOWN (towards the input/output glands)
    2. You have several options, depending on your specific JuiceBox enclosure version, for tightening down the relay:
      1. If the two 8-32 mounting screws are long enough, insert an included (⅛”) plastic standoff into each of the relay mounting holes
      2. [optional but helpful] remove the top of the relay to get to the nuts - use some needle nosed pliers to remove the vertical spring, and lift off the top
      3. Torque down the two locknuts - ensure the relay cannot be jiggled
      4. Be sure to reattach the top and the spring
      5. See below for a reference photo:

Note that above photo shows longer posts than what you may receive; the process is the same regardless.


  1. Wire power supply to the PCB
    1. Prepare 5x ~1.5” signal wires coming from connector.
    2. Solder one end of the wires to the row of 5 PCB pads on the Arduino end of the board (bottom right if looking at the board with natural text orientation)
    3. The other end is connected to the power supply via a connector.
    4. There are ~6” and ~8” signal wires, connected on one end to the AC terminals of the power supply – one wire to each terminal. Twist the first ~4” of the wires. These wires will go to the input terminals of the relay


  1. Mount the PCB / power supply assembly
    1. For PCB, use 4x 8-32 ½”-long fastening bolts, with 4x lock washers to securely fix the PCB to its aluminum posts (sequence: screw + lockwasher + optional flat washer). If you would like to use a flat washer, please make sure you are using washers small enough as to not contact any exposed metal around the hole.
    2. Orient PCB with the current sensors towards the bottom, close to the JuiceBox cable entrance
    3. For power supply:
      1. It may already come fixed to the enclosure. If not, continue;
      2. Remove the protective film from the two adhesive strips stuck to the bottom of your JuiceBox enclosure
      3. Remove the protective film (if any) from the bottom of your power supply
      4. Affix your power supply onto the adhesive strips, use a neat amount of silicone adhesive/sealant (electrical grade RTV) in addition to the adhesive strips.


  1. Prepare wiring for the relay
    1. Use ~3” and ~8” signal wires for the 2 ‘Relay’ positions of J2 connector (between current sensor and RL1 on PCB edge) – these will later be connected to the relay coil
    2. Use another set of wires of the same lengths for the 2 AC-Jside positions of J2 connector – these will later be connected to the AC_Jside (Normally Opened) relay terminals
    3. Solder one end of all wires to the PCB..
  2. Connect coil wires to the relay
    1. These are the wires coming from the ‘Relay’ positions of J2 connector on the PCB
    2. Coil terminals are the lowest terminals (closest to the relay’s base). You can also ID them by measuring resistance between each pair of terminals (between left and right terminal in a pair) – the one with non-infinite resistance is the coil pair
    3. See below images for visual reference:

Important reference guide for above photo:

The black leads are the “coil wires”, going from ‘Relay’ positions of ‘J2’ connector (PCB) to lowest coil terminals of relay.

The blue leads are the J1772 sense leads, going from ‘AC_Jside’ positions of ‘J2’ connector (PCB) to second furthest back set of terminals. Note: these should not be attached until after J1772 cable installation.

The white leads are the switching power supply lines, going from the two ‘AC’ terminals of the power supply to the furthest down terminals of the relay. Note: these should not be attached until after input cable installation.


  1. Wire the pilot line
    1. The pilot solder pad is located in the top right corner of the PCB (‘top’ is where the JuiceBox version is printed)
      1. See below photo for reference of pad location.
    2. Solder a 3”-long signal wire to this pad
    3. Connect this wire directly to the pilot line on your J cable (usually green). You can solder splice the connection or use a butt connector, just be sure to insulate the connection properly (we use ~¼” diameter heat shrink)
    4. Alternatively, you may choose to wire the pilot line from your J1772 cable directly to the pilot pad on the PCB. In this case, disregard this step until you install your cable.

  1. Cut a 3” signal wire and solder one end to one of the ground pads next to the pilot pad on the PCB. The two adjacent ground pads are equivalent. Use the other end to make a ring loop & thread it onto the ground post.


(8.9 board -  green “CP” line is pilot from J1772 cable, GND (from PCB to post) is soldered on underside of PCB here)


Your main Base Edition Main Unit is now fully assembled and is ready to be wired with input and output cables!

Part 2.D. Connecting the cables – BASE edition


  1. Connect the output J1772 cable
    1. Note that 70A cabling will be quite tight to pull through the sensors - but doable! Just be careful not to dislodge the sensors from the PCB - hold the sensor by its body while pulling the wires through it (i.e. do not hold PCB, hold the sensor)
    2. Remove the heat shrink wrapper on the end of the cable
    3. Normally ~6” of the cable jacket would already be stripped – strip back approximately 2” more. Use a rotary stripper, a pair of cable cutter, or even a razor blade if you’re crafty! Just be very careful not to cut the leads within the cable. If you do, be sure to heat shrink or electrical tape them to insulate. Add 3” to this if secondary current sensor (CS1) is installed.
    4. Cut back the leads to appropriate lengths:
      1. Red (hot #1) length should be cut back to about 9.5” from the orange jacket. (Add 3” to length if CS1 is installed.
      2. Black (hot #2) length should be cut back to about 4” from the orange jacket. Add 3” to length if CS1 is installed.
      3. Green and yellow (ground) should be cut back to about 5.5” from the orange jacket.
      4. Leave the thin green (pilot) line uncut for now

    1. Strip ~1/2” of the insulation from all 5 wires
    2. Crimp supplied AWG 6 lugs (for a high-amperage cable) or AWG 8-10 lugs (for a 32-Amp cable) to Ground (normally a striped thick wire), Hot1 and Hot2 wires
      1. Best to use a dedicated crimper
      2. Whatever method you use, ensure very tight compression fit that you cannot pull out with your hands
      3. Failure to crimp tightly will result in overheating of the wire and possibly melting insulation, etc
      4. Heatshrink (or electrical tape) the green and yellow line. For thinner cable (32A), go ahead and heatshrink the two hot leads (red and black) as well. For thicker cable (50-70A), leave the red and black leads raw for now - this will be helpful when inserting through current sensor on PCB

    1. Measure the resistance between Ground Wire (Green) and smaller gauge wires.
      1. One of the wires will have 150 Ohm resistance to Ground. This is the Proximity wire and is not used in your installation. Cut this wire flush with the J1772 cable jacket
      2. Smaller gauge wire that has no connection to Ground (infinite resistance) is the “Pilot” wire and will be used in your installation
    2. Thread the prepared J1772 cable through the output cable gland (the one on the right side)
    3. Place the ground lug onto the ground post
    4. Thread the two hot wires through the CS2 current sensor
    5. Connect hot line 1
      1. Sharply bend the wire to the left after it exits the current sensor
      2. Connect to the right AC-Jside relay terminal (see relay photo above), together with one of the AC wires from the J2 connector
      3. You may need to bend a lug slightly to avoid interfering with the J2 connector
      4. If you have a second current sensor installed, be sure to route this line through both sensors - CS1 and CS2.
    6. Connect hot line 2
      1. Bend the lug so that the wire exits the relay in the upward direction (see picture below)
      2. Bend the wire to the left to arc over to the left relay terminal for the bottom contact set
      3. Connect to the left AC-Jside relay terminal (see relay photo above), together with the second AC wire from the J2 connector
      4. If you have a second current sensor installed, route this line through only the first sensor - CS1.
    7. Ensure that the wires pass through the current sensor as parallel as possible, and are at the same height from the base of the sensor.
    8. Connect the pilot line (green for our cables) from the J1772 to the line you’ve made from the ‘Pilot’ pad of the PCB, or directly wire the pilot line from the J1772 cable to the PCB pad.
    9. Tighten the input and output glands so that the cables cannot be moved ar at all twisted around by pulling or pushing from the outside. Please apply a neat amount of silicone (electrical grade RTV) in the current sensor, unless it does not power up due to false GFI trips. If you do silicone now, and find GFI a problem later, it ought to be fine - silicone takes a while to set ;)

Thread the J1772 cable (and ALL leads) through the right cable gland, place the ground cable on the ground post of the enclosure, and route the two hot leads through the current sensor. This may be difficult for 50+ Amp rated cables - be sure to hold current sensor CS2 as they are being pushed through, as to not disrupt it. Try to keep the red and black leads parallel going through the sensor.

The black hot J1772 cable is bent immediately upon exit from CS2, and attached to right J-side terminal of relay (closest to PCB) - one of the signal wires from J2 connector (PCB) is fixed atop cable lug with a loop of wire, topped by washers.

The red hot J1772 cable is looped around the relay, over the power supply’s top, and attaches to left J-side terminal of relay (furthest from PCB) - one of the signal wires from J2 connector (PCB) is fixed atop cable lug with a loop of wire, topped by washers.

For this particular Base JuiceBox, the pilot line (thin, green) is wired directly from the J1772 cable to the “Pilot” pad of the PCB. The ground cable from the J1772 is attached to the ground post of the enclosure, along with the ground signal wire from the PCB. It is bolted down in this instance - it will need to be unbolted to accommodate the ground line from the input cable.

  1. Connect the input cable. Note that the instructions correspond to the standard input primary cable – EMotorWerks 240V cable with a 14-50P plug. If you are wiring your JuiceBox for any alternate input cable, make sure that the power is delivered to the input terminals of the relay (e.g. for a standard 120V cable this would mean that you should use phase (normally black) and neutral (normally white) wires – this is DIFFERENT from the instructions below so please pay attention)
    1. Remove ~4” of the outer cable jacket

      1. Completely remove the white lead, it is unused.


    1. Cut back leads to best lengths:
      1. Red (hot #1) should be cut back to about 3.5”, as should black (hot #2)
      2. Green (ground) should be cut back to about 2”.

    1. Strip back all leads about ⅜”
    2. Fit 3 lugs with #8 / #10 mounting holes to the hot (or hot & neutral for a 120V cable) and ground lines of the input cable. Use the two different supplied lug variants at your discretion - aim for easiest fit of stripped copper into lug body.
    3. Crimp lugs - the easiest way is with a hammer crimper or hydraulic press crimper.
    4. Heat shrink each connection as shown below:

    1. Thread the input cable through the input cable gland (left gland)
    2. Bolt hot #1 and one of the AC low-current wires (the one from the power supply’s AC terminals) onto one of the relay’s common positions
      1. Make sure that the high-current wire contacts the relay pad directly (i.e. a thin AC wire from power supply is NOT in between the relay pad and the hot line input)
    3. Bolt hot #2 and AC signal wire onto the other relay’s common position
    4. Place the ground lug onto the ground post

For your reference, types of plugs outlets and wiring diagrams for various types of sockets / plugs in the US:

(note that in this reference, 120V type cable is connected - your 240V cable will likely have red and black for hot lines, green for ground, white for neutral)

  1. J1772 alignment & calibration
      1. Properly align the J1772 hot cables:
        1. Failure to do so will show in false trips of the GFCI circuit above ~20-30A output
        2. You may need to adjust the wires if you are getting nuisance GFI trips (rare)


  • Most likely reason for JuiceBox disconnecting mid-charge is a false GFCI trip


        1. Most frequent reason for that is suboptimal alignment of power wires as they pass through the current sensor
        2. The best way to tune this alignment is to use a multimeter between Arduino pin A1 and ground :
          1. Has to be done when JuiceBox is charging your car
          2. Be careful not to short any pins with your multimeter probes
          3. As the current ramps up, you will see voltage rising on the multimeter
          4. Your objective is to change the orientation of wires to achieve a minimum reading on your multimeter
            1. If the JuiceBox trips before you have a chance to adjust alignment, lower the current limit by turning the appropriate current setting trimpot counterclockwise
              1. R20 if operating from 240V input
              2. R25 if operating from 120V input
          5. Once that’s accomplished, affix the wire orientation with silicone (electrical grade) caulk or similar material.
          6. See picture walkthrough:

By default, the value yielded by connecting the positive probe to Arduino pin A1 and the negative probe to ground (Base enclosure) is 213.8mV, in this instance of a locked 18A output. Your default value will scale, more or less linearly, with the amount of amperage you are outputting.

The orientation of the cables passing through the current sensor was changed (cable was twisted, hot leads were moved laterally) until a minimum voltage value was reached (49.5 mV here)

A small amount of silicone caulk/sealant (electrical grade) is used to seal the cable orientation in place, and the cable gland is completely tightened down to prevent any twisting.

        1. The second-best way to tune alignment is uploading the latest firmware and observing JuiceBox output on your PC (via a USB FTDI dongle)
          1. Connect FTDI to JuiceBox and PC (see instructions in the Programming section of this manual)
          2. Power up the JuiceBox
          3. Open the serial monitor in Arduino IDE
          4. note the value of inACpin variable reported by the firmware - it should be <500. If it is greater than 500, contact us
          5. as the output current ramps up, you will see this variable going up in regular (~1/second) printout from JuiceBox
          6. Adjust wire orientation to hit the minimum value of inACpin. Note that because of 1 second lag between readouts, you have to change orientation slowly in order to catch the minimum
        2. For the Serial Monitor method, if your JuiceBox trips before you have a chance to optimize wire orientation, just reduce the output current by turning the current setting trimpot counterclockwise before trying again
        3. If the above troubleshooting was not successful, best next step is to send us (JB-support email listed in front of this doc) a photo of your box (lid off) so we can see the wire orientation / connections.
    1. Secure the wires’ position in the sensor with some silicone sealant.

For reference, J1772 plug pinout below:

Your Base Edition JuiceBox is now fully assembled!

Part 3. Full Power Test / First Connection


  1. Ensure you follow proper High Voltage safety procedures
    1. Wear rubber-soled shoes
    2. Wear protective goggles
    3. Do not touch any terminals – even if you ‘know’ they are not live
      1. Be especially careful of inadvertently touching the live parts of the relay while holding the box – the box is metallic and grounded so there will be AC potential between the box and the relay terminals and contacts


  1. MAKE SURE ALL THE CONNECTIONS ARE TIGHT – double-check all the high-voltage connections – loose connections in a high-current circuit will likely mean overheating wires and melted isolation within a couple of minutes!
  2. [OPTIONAL] Place a current clamp-meter on one of the input lines
  3. Set current limit to the desired value (usually defined by the input circuit breaker / wiring)
    1. The adjustment is done via R20 trimpot on the main PCB (look for a small yellow head ~4-5mm in diameter)
    2. Left stop (counterclockwise) is defaulted to 30A in the firmware,
    3. Just to the right of that, the 0-60A range starts, ending at 60A at the right stop
    4. Example: to set 15A output current, you would turn the trimpot just a couple of degrees past ¼ turn from the leftmost position
    5. If you’d like to set exact amperage, there are 3 ways of doing so:
      1. With an FTDI cable connecting your JuiceBox and PC, the JB will report its settings ins a serial monitor (launched from Arduino IDE)
      2. Use a clamp current meter to measure the actual current flowing into the charging vehicle
      3. On an LCD (optional for base edition), the settings will be displayed on the screen
    6. 120V capacity is 15A by default, but that can be changed with trimpot R25.
  4. [OPTIONAL] Plug in your JuiceBox into a 120V outlet protected by GFI and / or a protected power strip
  5. If no immediate issues (e.g., sparks, smoke, etc), plug your JuiceBox into a 240V outlet
  6. Wait 15-30 seconds. JuiceBox should cycle the main relay. If that does not happen, something is wrong. Time to debug. Refer to the troubleshooting section of this document
  7. Plug your J1772 cable into the car
  8. Relay should close within a few seconds and stay closed
  9. Confirm charging by your car’s charging indicators
  10. [OPTIONAL] Monitor charging current with a clamp meter
    1. If Premium edition, confirm [approximate] agreement with the onboard current sensor (shown on LCD display)
    2. Confirm expected charging current (e.g., ~30A for a 6.6kW Nissan Leaf charger)
  11. [OPTIONAL] Monitor temperature every 1-2 minutes in the first 30 minutes of charge
    1. Use infrared thermometer
    2. Check all potential heat producers in a circular pattern following the power flow
      1. Input wires as they enter the relay
      2. Relay wiring and contacts
      3. Power wiring
    3. All contacts / wiring should show no more than 20-40C above ambient at any output current setting within 30 min
  12. [OPTIONAL] Monitor temperature every 15-30 min after the first 30 min until the end of charge
    1. All contacts / wiring should show no more than 30-50C above ambient at any output current setting
  13. Disconnect JuiceBox, close the lid.

Your JuiceBox is now fully functional and can be installed!

Part 4: Mounting your JuiceBox


In some of the early kits, we have pre-drilled 2 holes located on the vertical centerline of the enclosure. These should be the only 2 holes that are not yet occupied with the components.

For the most recent kit version, we are no longer drilling these holes to allow you the flexibility of mounting the boxes. In that case, adapt the mounting to your specific situations.


You can use a number of different techniques to mount the enclosure:


  1. Just drill the abovementioned holes on the vertical centerline. As mentioned in one of the first parts of this document, you might want to drill these before you mount any of the internal components. If that’s the case, try to position these holes ~3/8" to the left of the PCB (align the PCB with PCB mounting studs for reference). Drill ~1” from the bottom and top of the enclosure. That way you should have enough clearance from components after assembly. Do not forget to seal the screw’s head from the inside with generous amount of silicone sealant (electrical grade RTV).


  1. Via a mounting bracket
    1. Option 1: We now have a mounting bracket specifically designed for Base Edition! It allows you to slide your Base unit in and out in seconds, making the unit truly portable - check it out in our online store!

    1. Option 2: a 20” piece of 2”-wide galvanized steel plate gauge 16 or thinner (higher gauge) (you should be able to find that in Home Depot of a similar store), bent to form a horizontal bracket on top of your JuiceBox - this shape:

For full weather protection, use a silicone sealant around your bolts to seal off the water.


Part 5: Using your JuiceBox

WiFi operation (requires optional WiFi shield / module):



      1. The data you see is for charging our company cars - a set of RAV4EVs and Nissan Leafs


  • Ensure your WiFi module is appropriately configured (per instructions in one of the appendices in this document)
  • Power up your JuiceBox, wait until it goes into the standby mode (~10 seconds for Base, ~30 seconds for Premium)
  • Connect to your JuiceBox via FTDI, and open a serial monitor. The long ID string is your key.
  • Write down that ID and bring it to your internet-connected PC
  • On your PC, open a web browser and go to<ID>&timeunit=1  (instead of <ID>, enter your unique ID - without ‘<’ / ’>’ symbols and line breaks)
  • If your JuiceBox has previously successfully connected to our server, you will see some charts your browser window along with some timestamps. If not, you will see a ‘no data’ error message


      1. Note that it takes 10 minutes of runtime in standby or 1 minute during charging for JuiceBox to start sending data - it is normal not to see any data in the first few minutes after powering up your JuiceBox for the first time. Dependent on your firmware version, results may be immediate.


  • If you do see a ‘no data’ error message after more than a few minutes of charging, please repeat the steps in this section and if still cannot see the data, contact us at JB-support email address mentioned in the beginning of this document




You now have one of the best EVSEs  money can buy.


More powerful.


      More extensible.


             More mobile.




                             More protected.

And you built it yourself!


Go Electric!


Yours truly,

Electric Motor Werks Power Electronics Crew



Appendix A.1: WiFi Installation (from WiFi kit) (simple edition):

Appendix A.2: Configuring (Programming) your WiFi installation:


Appendix B.1: Arduino Programming - Main Firmware:


Appendix C.1. Logic Test:

Appendix C.2. Verify J1772 Logic of Unit with no J1772 Cable:


Appendix D: JuiceBox Base Edition MODS!

MOD 1: Adding LCD to your Base JuiceBox:

MOD 2: Adding Remote Antenna WiFi to your Base JuiceBox

MOD 3: Add a Current Sensor to your BASE JuiceBox

MOD 4: Enhance your JuiceBox’s RTC (Real Time Clock) Capabilities


` Appendix E. Troubleshooting:


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