ElectroClassic EV
Classic Cars Reborn into the Electric Future

J1772 Receptacle Hack

Above is the original J1772 adapter box that was purchased from Tuscon EV. My plan is to put it behind the front license plate, but unfortunately the box above is about an inch too thick, and a little too bulky for my scheme. No problem. I immediately voided the warranty by grabbing a screwdriver and touring the innards. There was nothing too complicated inside except a little circuit board sporting a diode and two resistors. No reason I couldn’t stuff these guts into a box with a smaller, thinner profile.


Here is a smaller single gang junction box that has been chopped down about an inch using a coping saw, and rubbed on a sheet of 400 grade sandpaper to level and smooth the top edge. The four faceplate mounting screw holes also needed to be drilled out, but no further mods were required to the box, so I proceeded to the faceplate.


Here is the original faceplate on the left, and the new faceplate on the right, fabricated from a standard blank cover for the small box. I moved the microswitch and indicator bulb to the right of the receptacle to allow better access with a lower vertical footprint.


I diagrammed the circuit path through the components and switch before removing them from the circuit board. They were then reassembled on the bottom of the switch with a soldering iron and shrink tubing for insulation. The two resistors and diode are now inside the black shrink tubing on the switch. I’m crossing my fingers that they won’t need better ventilation.


Here is the backside of the new faceplate, with all the hacked components installed. The indicator bulb fixture was originally a bit longer, and also needed some doctoring to make it fit in the shallower new box.


Into a smaller box this could not fit. A short plastic sprinkler pipe is glued into the side collar, and then covered with a threaded PVC cap with a hole drilled for the cable to exit. A compression washer under the PVC cap will keep water out of the cable fitting. The receptacle hatch does not close as snugly as desired, so I will probably remove the yellow insert and use it as a pattern for thicker, more weather-tight foam.


A window has been cut in the original stock bumper to allow access to the J1772 charging port that will be mounted underneath. This sacrilege is entirely justifiable in the name of good design. It’s less of a heresy given that I had already done some metal repair and replacement on the front bumper. The above hole will be fine sanded, given a couple coats of primer and then painted satin black. A flip-down license plate holder will conceal the entire deal.


The top picture shows how the receptacle was attached to the body with masking tape to test the bumper fit. It needs to be oriented so the mounting screws don’t interfere with the hood latch and deck shelf inside the trunk. Once the best position was located, holes were marked and drilled to mount the J-box as seen above. Nylon spacers were used to raise the receptacle slightly away from the curved surface of the car body, and an inch diameter hole was drilled to the left of the J-box to provide cable access to the charger in the former fuel bay.


I ended up buying two spring-loaded license plate holders, because the first one did not have a stay to keep the plate in the open position. My second purchase was a 1982 Camaro flip-down plate holder that smartly stays in the down position when opened. Once the J-box was installed, the plate holder was positioned to conceal the charging receptacle window, and two holes were drilled for rivnut mounts. More nylon spacers were used to stand the plate holder away from the bumper and charging port cap, and then a couple test fits helped me decide that I liked the Camaro plate holder best.


Here’s what the compressed rivnut looks like on the backside of the bumper. That centipede-looking thing curled around the bottom is actually the pleated section of the rivnut that gets crushed down and squeezes it solid into the hole. Sort of like Santa Claus getting permanently stuck in a chimney. What remains is a threaded sleeve that eliminates the need for a nut. This provides a way to mount or unmount my license plate holder without removing the entire bumper.


Here’s the finished install of the J1772 charging receptacle mated with a J-plug that was purchased for home charging. I will create a few adapters for the J-plug side that allows docking to standard NEMA household 110 and 220 VAC outlets, and carry those items in my trunk. Public chargers, on the other hand, require a little more technology. A normal AC outlet will dispense electricity immediately when you plug into it, but a public J1772 charging station includes a safety feature that withholds electrons until it detects a pilot signal from the vehicle. Store-bought electric cars have pilot signal circuitry built-in to the charging system, but an off-the-shelf charger for an EV conversion doesn’t (currently).  This is where the little switch on the receptacle comes into play. After the plug is docked, flipping the microswitch to the on position will generate a pilot signal that lights the bulb and starts the magic flow of electrons. Once the charging session is done, flipping the switch off stops the flow, allowing a safe disconnect of the J-plug without the hazard of high current arcing.


The end result is a perfectly innocuous license plate, concealing secret powers from an unsuspecting public that will shape the destiny of the world.



3 Responses to “J1772 Receptacle Hack”

  1. Your mouth to God’s ears. I hope you are right.

  2. I think this setup looks as fantastic as it is functional – and therefore passes the “Form follows function” rule Porsche laid out all those years ago. This is clearly a better approach then putting the charging plug under the front trunk “to maintain originality.” It makes sense to have it there for a three minute standing right there gas fill-up, but doesn’t make sense for 20 minute charge while you run into the store for groceries.

    For the bumper – did you dechrome it before painting it black? Did you respray the whole bumper with the satin paint? Are you going to put black factory grills over the fog light area?

    • Hey Rob

      Thanks for the nod. You are absolutely right about leaving the trunk open all night to charge, or in the mall parking garage. Not gonna happen.

      As for the bumpers – they came black from the previous owner. I don’t think they were ever chrome. I had some straightening, hole-filling and finish bodywork done on both front and back bumpers:

      I then used satin black on them, like all of the other black external body parts/features. The grills were purchased from either Pelican or Automobile Atlanta, and are a high impact black plastic, each with a hole for the driving light.


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