Based on the OpenEVSE project


OpenEVSE Store

Arduino Electric Vehicle Charging Station "Electric Vehicle Supply Equipment" (EVSE) implementing the J1772 protocol.

J1772 is used in the current generation of Electric Vehicles and Plug ins such as the Nissan LEAF and Chevy Volt.

The EVSE advertises the Maximum current available to the EV with a 1khz pilot signal. The Duty Cycle of the pilot sets the available current the EV may draw. The EVSE also functions as a safety device, the 240V AC lines of the J1772 plug are not hot until the EVSE and EV command the start of charging. The EVSE also functions as A ground fault interrupt device (GFCI).

Parts list and Schematics are attached as images.

Step 1: Setup ARDUINO Shield

Build and ARDUINO proto shield.

I used the Shield from Adafruit. http://www.adafruit.com/products/55

Solder 2 x 8pin and 2 x 6pin headers to the outside holes.

Solder 2 x 5mm 2 Position Terminal headers to the protoboard for the Relay and J1772 Pilot
<p>I see how the GFCI circuit triggers, but how does it reset once the fault is cleared? Once the capacitor (0.1 uF?) in the feedback loop of the first op-amp is charged to a high enough voltage to send the output of the second [comparator] op-amp high how does it discharge again?</p><p>Also: it seems that later versions of OpenEVSE can do a self-test of the GFCI system at start-up, sending a small current through a winding on the outside of the CT toroid to confirm that the system works; I cannot find a schematic which shows this. Can anyone offer any enlightenment?</p>
<p>If the output which the EVSE will be connected is already protected by a residential GFCI, can the EVSE one be omitted for lower cost ?</p><p>Obviously with some code changes to not monitor it.</p>
Excellent project. How much did the whole thing cost. I already have my J1772 plug and inlet for my EV, now all I need is to build this kit. I was wondering what the build cost was? Thanks in advance and I look forward to testing this unit!
<p>Dear Sirs.</p><p>I am also in progress to load my Renault Kangoo with 16A in single wire 240V.</p><p>But I am alsolut not able to do that, and I don&acute;t know why.</p><p>Did anybody have a scrennshot of the Pilot signal?</p><p>Regards </p><p>Carsten</p>
<p>@arwooldridge</p><p>At 12V there is no 1000hz output, it is DC until the resistance drops the voltage to 9v.</p><p>Negative -12v is to support the J1772 diode check. Many commercial units skip this check but it is important to detect a real EV resistance vs. dropping the handle in a puddle of mud.</p><p>Sure, you could implement the protocol with analog circuits, but it would likely be a much more complicated circuit unless you skipped many of the required safety features such as diode check, ground monitoring, stuck relay check, GFCI, GFCI self check.</p><p>OpenEVSE was designed to implement all required safety checks, it is still a relatively simple circuit even with a microprocessor.</p>
<p>That's interesting that it gives a 12 volt 1000Hz output straight away. Suggesting its not necessary to output +12volts DC on open circuit.</p><p>I checked my Polar networks Chargemaster outlet.</p><p>It gives +12volt DC at CP on open circuit and gives a 1kHz 25% PWM ( its a 16amp outlet) 9 volt output when loaded with 2.7kohms. Again it does not go negative suggesting this is not necessary.</p><p>You could make a very simple circuit indeed, without microprocessor just a dual or quad comparator on the peak rectified CP signal, and a quad Schmidt nand CMOS gate and a counter ( one Schmidt to make the oscillator the others for PWM selection and gating) Add a transistor, relay, and RCD for a very simple low cost charging outlet.</p><p>In fact the J1772 protocol was designed to be easily implemented without processor.</p>
<p>I think the Circuit could be simplified a bit, since using a pilot pulsing at 1000Hz using ordinary square pulses, with 0V for off and 12V for on works perfectly with many cars. </p><p>I bought an aftermarket charge-cable/controller here in Norway, which I have used for a year and half on my Nissan LEAF. I connected a oscilloscope to the CP (pilot signal) the other day, and saw that it just pulsed between 0V and 12V when unconnected. The circuit just used a decade counter coupled with 1N4148 diodes on the output to the car, so also no other possibility in that circuit!</p><p>The cable/controller is said to be compatible with LEAF, Mitsubishi MIEV, etc, so I guess the cars isn't that picky!</p>
Never mind, saw the price and built specs above on the first step. Missed that the first read through. I'm going to try and get the parts and build this tomorrow.<br><br>Thanks for this project. Excellent work. I'm going to test it on a Plug In Prius I have.

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