Build Your Own J1772 Charge Station – The Electric Porsche 914

This week we feature Richard Rodriguez’s excellent Porsche 914 Targa build. Richard shot an excellent video walk around of this car, which does 100 mph and of course over 100 miles range using somewhat unusual Voltronix batteries from Flux Power. Flux Power was started by the ex-CEO of Aptera Motors.

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One of our viewers suggested we show how little is really inside the $3000 Clipper Creek Level II Charge Station and so we did. We went a bit further. We gathered up all the pieces you would need to build an SAE J1772-2010 Electrive Vehicle Service Equipment (EVSE) 60 amp charge station. All in, it is right about $900 and would would probably take 2 hours to assemble.

David Kerzel’s J1772 control board is of course what makes it possible. But we found an enclosure with TWO 90 amp contractors on eBay for $299. This gives you an approved enclosure and approved contractor for your box.

We also added a GFI 60amp circuit breaker for $117 including shipping. It’s a Siemens ITE BF260 model.

Of course, you need a plug and cable. We get the 70Amp model with 8 meter cord from Chennic for $175 plus shipping.

Beyond that you’re into optional switches and a $2 automotive relay. The contractor works on 120vac across its coil. We use the 12v automotive relay to apply this voltage on command from the modularEV control board.

Here’s a little wiring diagram that might help you put all this together.

David Kerzel was sufficiently wowed by our combination of his billet aluminum J1772 socket and the billet aluminum gas cap, that he’s going to get the caps, and make a totally integrated gas cap/J1772 socket with LED lights and his little control board to sell as a package. Would have saved us some work and having seen his machining work, it will undoubtedly look better as well. Since the caps are about $130 and his billet socket is $160, the board is $30, the little device is likely to be a bit pricey, certainly over $350. But it would provide a very nice total solution to mount on a car for J1772 compatibility. And it would be kewell.

We also talk about the CABLED study from Coventry and Birmingham in the UK. This is real data collected by satellite. And it very seriously calls into question the question of infrastructure. Most EV proponents are campaigning vigorously for public charge stations in their cities. We have been a little reluctant on this, and at this point we’re actually against it. Getting the government, federal, state, local et al, to fund charge stations no one is going to use seems like a bad approach. Level II charging is best done at home and so is generally done at home.

We can see some utility in Level II charge stations at your place of employment. Tax credits for employers are I think already available but this area should certainly be pursued.

But public Level II charging never did really make any sense at all. Walmart is going to install 830 charge stations. It’s goofy. I’m only going to be in Walmart for 45 minutes and I wouldn’t even bother plugging in the cord if I DID accidentally get one of those parking spots.

We need Level III charging spots between cities that can bring our car to 80% in 30 minutes. This would allow intercity travel. I can deal with driving 100 miles (two hours) and taking a 30 minute break, particularly if coffee is available. It would be a rather leisurely drive and we’d be talking 300 miles in a day perhaps – 400 if you are aggressive. But it would allow cross country travel. And the number of these stops is within the scope of do ability even across the land.

The batteries will already do it. We need a CHARGER on the car that will talk ChaDemo or Level III, when adopted, and that is non trivial. It’s not just a communications issue. The Level III will be a couple hundred amps at up to 400v DC. But it can be done.

Gas stations are the obvious place for this, and you will have to pay for it – probably through the nose. But I’d pay $20 for a quick charge that would get me city to city. Still a bargain compared to gasoline.

I think this is the “charge station” we should be focused on. Free electricity at the mall just doesn’t work for me – unless I happen to work at the mall. The only ones to benefit from Walmart’s charging stations would be Walmart employees with electric cars.

Here is a link to the J1772 spec as revised January 2010.

Jack Rickard

29 thoughts on “Build Your Own J1772 Charge Station – The Electric Porsche 914”

  1. I like your J17772 charger DIY. I would like to make 2 recommendations.

    I think the automotive 12V relay probably isn’t rated for a 120VAC on contacts nor is it UL listed. But I could be wrong since I don’t have the specs.

    If you move the GFI Breaker into the the breaker panel this eliminates the need for a second breaker. This would require a 240V power supply to get your 12VDC. Your main contactor coil voltage would also need to be the 240VAC version.

    Thanks, Jim

  2. Jack,

    Nice show! You clearly demonstrate that there is not much inside an EVSE and that it is not difficult to make one.

    But I think the description of how to wire up the DIY J1772 EVSE may not quite be correct. First, although ground and neutral are tied together at the breaker panel box, they should not be tied together or confused with each other after that. Ground should be used to ground devices and should not carry current except in the case of a fault (failure). Neutral can carry current in a normal (non-fault) condition. Second, if the J1772 connector supplies ground (which I am guessing that it does), then that conductor should be directly connected to ground and should not be connected to the neutral conductor of the GFI breaker. Here is a link to Siemen’s documentation showing this:

    I think the reason that ground and neutral are separate after the main breaker panel is that if a neutral wire carrying current breaks or has a loose connection, it may go to a non-ground (zero) voltage. You don’t want your device (e.g. car) surfaces to also do that!

  3. Hmmm. The automotive circuit breaker is rated for 40 amps DC. I need to switch 120vac at 50 ma. But you’re right it’s not UL listed.

    If I put a GFI breaker in the panel, I have to have a 240vac DC power supply for 12 v, and replace the 120vac coil with a 240vac coil, else wise I introduce an imbalance in the branch and trip the breaker constantly. That’s basically why its the last thing in the box. I’m not worried about electrocuting the contactor.

    Guessing is not good practice. The J1772 does not carry a ground. It has the two phases and neutral, and neutral is not tied to the frame ground in the car.

    The Elcon and Brusa chargers we favor are isolated, but it’s true we do have one vehicle with a Manzanita that is not.

    The diagram is perhaps incorrect. We would indeed tie ground to the enclosure and neutral to an isolated post not tied to the case. The 12v supply and the GND on the control board would have to be tied to that neutral as they are all referenced to the neutral in the J1772 connector.

    As to the reason ground and neutral are separate, you may be saying the same thing, but another viewer had already noted it in terms I can understand better. Neutral carries current and ground normally does not. With the neutral operating normally it would carry current and so the two are at potentially at two different levels and you want your washing machine frame tied to the green one…true earth ground.

    Jack Rickard

  4. Hi Jack !

    Doesn’t the GFI measure the sums of the phases in relation to what comes back on the neutral to see that no current is lost in the circuit(if some current is lost it will have passed to ground some other way). Therefore I think it will work fine to have the GFI before the Contactor and the 12v supply. The GFI will only break if the sums of the both phases does not match the return on the neutral.


  5. Jack,

    For what it is worth, I was just looking at the J1772 wikipedia page and I found a link to the J1772 SAE spec ( It seems to specify that pin 5 of the J1772 connector is a ground rather than a neutral. Specifically it lists the connector side pin 5 as “equipment ground” and the inlet side pin 5 as “chassis ground” where “Chassis ground” is defined as “the conductor used to connect the non-current carrying metal parts of the vehicle high voltage system to the equipment ground”. There is also a nice EVSE circuit diagram in that document.

  6. A lot of expertise being thrown around here.

    An imbalance between the phases will trip the GFI. If I take power out of one phase and not an equal amount out of the other it will trip. It actually compares the two phases and trips, in this case, on a 30 ma difference.

    Yes, the document you site does indicate pin 5 is ground. I guess i would stand corrected. However, this is the 1996 version of SAE J1772. The 2010 version past last year is the currently used version, with an entirely new plug and a somewhat different scheme.

    SAE J1772-2010 specifices pin 5 as the proximity pin. There is no earth ground in the connection. Pins 1 and 2 are phases, pin 3 neutral, pin 4 co-pilot signal, and pin 5 is proximity switch – tied in with the little button on the plug itself.


    There are dozens of ways to do this and dozens of ways to wire it up. GFI isn’t technically needed at all. And indeed most of the EVSE doesn’t have it. They expect you to run one in the panel, as suggested.

    You don’t need to build this at all. GE is going to offer their Wattstation at Lowes.

    This was a quick and dirty build of a perfectly operational and I think perfectly safe J1772 EVZSE using crap found on eBay for $900. But that price is based on the fact that you can buy perfectly new components on eBay that are surplus and have been around for years. Either of the contractors that came in this “motor starter” would be $500 bought new from normal distributors. This was kind of a how to on making your own using inexpensive parts – not how to design one for production.

    I think it would work. I have them working. They charge great. Haven’t killed me yet. Would charge a Leaf or a Volt or any J1772 compliant car just as well.


  7. Jack,

    I am not trying to be a pain, but everywhere that I look I see “ground”, not “neutral” on the J1772 connector. I admit that I have not purchased the official J1772-2010 document, but even the SAE article on the approval of the 2010 spec labels the connector pin as “ground” ( Since most of the commercial EVSEs only have three wire connections (L1, L2, and ground), it sure does not seem like the J1772 spec can have a neutral connection. (For example, see If you have a copy of the actual J1772-2010 document, could you please double check this?

    I am only pointing this out because the difference between neutral and ground can be very important in the event of failures.

  8. Going from a purely logical point of view, I’d think you want to carry both hot sides and earth ground out to the charger in the EV. I say this because you need 240vac for powering the charger and I’d want the case of the charger tied to earth ground via a non-current carrying conductor. Just like any other properly installed, up to date, 240vac appliance in ones home.

  9. Steve:

    The J1772 2010 spec provides for FIVE pins. Three large ones are L1 and L2 and of course the NEUTRAL return for the current. Pin 4 is the co-pilot signal and pin 5 is the proximity switch.

    All carry current. Albeit very small amounts on 4 and 5.

    It is what it is.


  10. Steve:

    You’re not a pain. I stand corrected. Not too sure I understand it. But I’ve added a link to the J1772 2010 spec and it clearly shows pin 3 as earth ground – equipment ground on the EVSE side and vehicle ground on the car side.

    I’guess I don’t quite understand where the two 120v phases are getting their return, except through the ground, which shouldn’t technically carry current. So I’m a little unclear here.

    Somebody splain it to me????

  11. If the charger runs on 240VAC then they don’t need a return. The only case that a return is needed is for a 120VAC. The return is simply a center tap of the secondary pole transformer. Again not needed if what your driving is purely 240VAC. So only 3 wires are required two hot legs @ 120VAC and ground.

    If anything in the EV runs on single leg 120VAC while plugged into 240VAC the J1772 will not work!

    They do make converters though for 120V – J1772.

    All they are doing here is changing out one hot leg for 1 neutral.

    Thanks, Jim

  12. Jack,

    With all this Ground vs Neutral talk going around, I also got confused. So I against my better judgment I decided it was time to get the latest SAE J1772 document. (“(R) SAE Electric Vehicle and Plug in Hybrid Electric Vehicle Conductive Charge Coupler”, Revised 2010-01). 51 pages. Oh my! We are not in Kansas anymore.

    Grounding: On Page 10, “FIGURE 2 – AC LEVEL 1 AND AC LEVEL 2 CONDUCTIVE COUPLER CONTACT INTERFACE FUNCTIONS”, you will note that on the EV Connector side of the coupler interface Pin 3 is labeled “Equipment Ground”. On the EV Inlet side it is labeled “Chassis Ground”.

    This connection is to protect the user in the event of a ground fault. As I recall (and I will let others correct me if I am wrong), NFPA 70 requires that the ground conductor be large enough to trip the branch circuit breaker even without GFI protection. Why SAE J1772 labels the function of Pin 3 differently on either side of the interface will remain known only to the clandestine standards group.

    Level 1 Charging: Level 1 charging is used for those chargers that use only 120 VAC or those that accept dual voltage. As several have commented you need to have a Neutral return when charging from a 120 VAC outlet.

    Page 11, “FIGURE 3 – AC LEVEL 1 SYSTEM CONFIGURATION” shows that for Level 1 charging, the neutral wire is connected to Pin 2 “L2 or N” of the connector. Note the system diagram for the Level 1 EVSE shows a contactor that is controlled by the Control Pilot signal and opens BOTH the hot and neutral lines from the incoming power. This is something to consider when you want to use Level 1 charging on the road. It seems to dictate we have an EVSE box (either portable or installed in the vehicle) that plugs into the 120 VAC source or risk overcharging our batteries.

    AC Level 2 Charging: Page 12, “FIGURE 4 – AC LEVEL 2 SYSTEM CONFIGURATION” shows that Pins 1 and 2 are connected to L1 and L2 of the 240 VAC source. No neutral connection is provided so as Jack has commented, all components in the vehicle charging system must be capable of operating from 240 VAC or a supply voltage derived for that source. For dual voltage chargers this requires a design that operates over a two to one voltage swing.

    Note that again a connection is provided from Equipment Ground through Pin 3 of the J1772 plug to Chassis Ground in the vehicle. Also note that in both cases a “GFI” signal is pictorially connected into the “Control Electronics” of the EVSE. How this is implemented is left to the designer.

    At this point I have only completed reading ¼ of the document. The next mind bender is to tackle is the Control Pilot signal.

    Hope this is sufficient clarification.


  13. FYI, Schneider Electric (previously Square D) offers a model EV2430WS charging station which is 30A level-2 with GFI for $1200 list ( Steven Engineering in San Francisco ( shows it at $840 as a special order. I’m not sure how real this is except that I found it at list price on eBay (

    Regarding EV noise-makers: aren’t most modern cars, and all hybrids, nearly silent at idle and blend into the background sounds just like EVs? Shouldn’t all cars require noise-makers…you know, just to be safe?


  14. Jack

    Great post, esp the commentary on charging stations. The Level III charging stations between cities and in cities are a thing that would make good business sense too. An earlier version of me would have advocated government involvement in building the national EV infrastructure akin to the Eisenhower highway system, but I’m rapidly losing faith in government’s ability to do anything but waste our money. Just a couple of notes on your Level III charging stations comments.

    The company that’s putting in the 800 stations I think is Walgreens (I don’t know whether Wal-Mart is doing that or not). It actually makes more sense that it is Walgreens (as opposed to Wal-Mart), in that they’re flipping upside down the notion of a gas-station adding a convenience store to its services…they’re roughly a convenience drugstore adding EV Charging Stations to their stores. Many of their stores are located proximal to many highways and freeways, and if they commit to making Level III charging a priority (they’re mulling over the appropriate balance of Level II/III stations) it makes even more sense.

    And it turns out that AAA is considering a ‘mobile’ version of what you are proposing (mobile Level III charging).


  15. @pm_dawn

    Do you happen to know about more information om elbilar? Particularly for the Stockholm län or Uppsala län?

    Do you know if there are many people doing conversions and if the government subsidies are limited only to new elbilar or will they work for conversions också?


  16. Davide Andrea is not only putting up new videos, he’s disabled commenting and deleted all my comments pointing out his rather blatant errors. Now his misinformation can go unchallenged.

  17. Yeah, Davide is a piece of work.

    In the comments he deleted were two points I made. I only repeat them here so that someone investigating Elithion mishaps may still be able to find them:

    First, it seems one of his top balancing schemes is to cycle the charger, at full current, on until one of the cells hits 4.2 (or whatever) volts, then shut it off until the pack drops to 3.8vpc, then cycle on until a cell hits 4.2 again, cycle off until the pack drops again to 3.8vpc, and repeat. He gives no indication when this cycling would stop. If that’s a charge profile, then there’s a place to look as the source of a fire, since it seems to me the pack would be grossly overcharged doing this, especially with no end point.

    The other point I made is that these videos are a very interesting and valuable set of statements by Mr. Andrea. If I were, say, suing his little company (and maybe a better-insured distributor of his wares) for damages from a fire in an Elithion-equipped car, these very marketing messages would handily demonstrate, if not the mechanism of a charging fire, then at least that Davide hasn’t the foggiest idea how to charge these batteries, let alone automate the process flawlessly. These videos are the core of a blistering cross-examination, and easy pickings for any (even half-assed) expert witness testimony.

    Look, the American legal system is a lot of things, but one nice thing about it is that it makes quick work of hustlers and charlatans like Davide Andrea who put firestarters into the stream of commerce for profit. Anyone who resells and/or installs these things for money is likely also to be joined thereby as a defendant, particularly if there is a death. That’s doubly so if Elithion is underinsured, goes belly up, and Mr. Andrea proves judgement-proof.

    All of that is a very real risk, regardless the outcome of any one case, and that risk will eventually render his products commercially undistributable, and professionally uninstallable. Let’s hope that happens before there’s another Elithion fire. Its only a matter of time, really.

    So the videos should stay up, and someone ought to archive them for the benefit of current and future elithion fire victims, lest Davide figure out one day just how much legal exposure his asinine lectures are providing him.

    Over & out,


  18. Pin 3 of the J1772 connector is not a neutral return for the current. As per the J1772 spec, revised January 2010, it is equipment ground (A green wire, a bare wire or a green wire with a yellow stripe). It’s intended to only carry a current during a fault condition to protect lives and property. In the case of a 115vac installation, the return current (white wire in the US) is tied to pin 2 of the J1772, again as per the J1772 spec.

  19. In 240V circuits the neutral is never used. After all, by definition, there’s a 240v differential between the two hot phases. When I wire equipment outlets we usually only run 3 wires: the two hots and ground. The reason that the neutral IS run for things like stove circuits is to provide 120V for something like a clock or lights in the stove.

    You could use that second contactor to switch pin 2 from the red wire to the white wire within the EVSE. Then your box could charge a car that could only handle level 1 charging as well.

  20. A clarification question on the (co)Pilot signal? Other than for the Error condition of it being -12vDC, does the digital waveform have to go down to -12v or a digial wave form between +12v (or reduced by the signalling mode to 9v, 6v, etc) and 0v.

    If pilot digital requires a the full negative excursion, how it being produced with many designs using a single +12vDC power supply, (that is no -12vDC supply)?

    Chacko the Solangelist.

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