J1772 Charging - The Joy and the Agony

I continued with the work on the J1772 upgrade from yesterday.  Here I've tidied the wiring and zip-tied the wires in place.

I painted the gray epoxy repair holding the front battery in place with white plastic paint.

The box is now mounted to the side of the battery box.  You can see the nut holding the transformer bolt into place.  This will cause me some anguish shortly, I should have seen it coming...

Finally the battery box is back in and the batteries are dropped into place.

The batteries are wired up and the PakTrakr leads are all re-installed.

I did another 120V and J1772 test, both passed!  Note that I didn't tie the box's 120V output into the charger yet, so there's no load on the output.

Since the initial side-mounting for the relay box was inaccessible, I decided to mount it right on the top of the front battery box cover.  This will give me easy access to the fuses and the wiring.  I got another PVC enclosure and put the cable glands on the right side.  I attached heavy strength Velcro to the bottom, so if I need to get to the batteries, I pull the box off the Velcro and move it to the right side.  Now I just have to move the redo all of the wiring.

And here is the final result!  This is now the overall front trunk layout.  Dual charging plugs are on the left, control circuitry in the middle in a NEMA-rated enclosure, and a twist-apart AC disconnect on the right side.

Here's a close-up of the control circuitry.  Moving it to this position makes it far easier to check for blown fuses and future upgrades.

After the wiring was complete, I plugged in for yet another charger test.  Note that this was the first one with the load of the charger filling the battery pack.  After a few seconds, I saw smoke coming out of the J1772 box!  Fudge bucket!

That led to an adventure of getting the J1772 box out.  I had two problems that I should have recognized during the design.

First, the bottom bolt is mostly inaccessible - I could touch it with my fingers, but couldn't get a wrench on it.  I ended up taking out the battery adjacent to the J1772 box and drilling out the bottom bolt from inside the battery box.  I won't replace the bottom bolt because it's not necessary for holding the box in place.

Second, the big nut on the outside of the cover on the transformer bolt is about 1/4" too long and the side of the headlight area was blocking the box sliding up.  I managed to get a ratcheting socket on the nut and got it off, but the bolt was still too long.  After a lot of swearing, I drilled a 1" hole through the wall of the battery box where the head of the transformer bolt is.  I then backed out the bolt through the hole.  The J1772 box then lifted right up.

My guess was that I had botched the wiring on the AVC1 board and melted it, but when I opened it up, I found the board seemed to be in good shape, but the small wire I used for ground was crispy where the insulation used to be.

I sent an email to David Kerzel of Modular EV Power at 7:00 PM on a Sunday night hoping for a reply sometime tomorrow but he wrote back in 30 minutes!  He asked some questions about the wiring, so I've sent him my schematic and we're going back and forth on the problem.  Great customer service!

I need to get the car rolling for the Warbirds, Wings and Wheels car show this coming Saturday!  Luckily I have about 80% charge and the show is a couple of miles from my house so the charging circuit doesn't really need to be working for the show.  I'll just re-mount the box and tell everyone it works perfectly!  Update: It did work!

Here is the schematic of the full charging system.

J1772 Charging Upgrade

What do you do with a working electric car?  Tear it apart and add more parts!

I bought the 120V charger with the goal of being able to charge up wherever I can find a 120V wall outlet.  That's great for home and any houses I visit or my work building, but electric vehicle charging stations with the J1772 plug are popping up everywhere.  I don't want to miss charging from one of these stations just because I don't have the right socket in the car.

I initially thought that I could install the J1772 socket and then run the power wires in parallel with the existing 120V socket and charging circuit.  Imagine my frustration when I found that you cannot derive the needed 120V neutral conductor from a 240V J1772 plug.  J1772 does specify a 120V option, called Level 1, but it's not supported by my Schneider unit and most other public charging stations.

So I had two tasks: step down from 240V to 120V and derive Hot, Neutral and Ground wires for the 120V circuit.  The solution comes in the form of a toroidal autotransformer.  I was given a pointer for this type of device to Toroid Corporation of Maryland.  They build a standard list of autotransformers, but I needed 240V in, 120V out and 15 amps of capacity.  As you can see from the table, they don't offer that as an off-the-shelf unit.  I contacted them and told them what I was looking for, and they replied back with a custom design, spec sheet and price quote.  I confirmed with my power engineer friend at work that this was, in fact, the part that I needed.  After confirmation, I sent my order in along with $228.41 and was told to expect it in a little over a week.

In the meantime, I worked on some prototypes to see where I would be able to fit it, in the tight confines of the front trunk.  I measured the available space with the battery box in place in the front trunk.  Then I built a cardboard mockup about the size of the real transformer.

I first tried a case with a clear removable cover from Polycase like I've used in other locations in the car.

It is definitely a tight fit!  Let's see how the plugs fit along the top edge... again very tight but not bad.

But my decision was made - the power sockets stick down too far to get the wires mounted and routed within the box.

I found this Cantex box at Lowes that just barely fits.  I held it in place with my endless supply of woodworking clamps, and drilled holes for the top and bottom bolts.  The top is a through-bolt but the bottom is a rivnut so the bolt head doesn't stick into the side of the battery on the other side of the battery box wall.

And here's the mockup with the transformer and both power sockets drilled and set into place.

Here's what the sockets look like from the top - just right.

Now we move on to positioning the real transformer.  You can also see the passive air vents I installed in the bottom and side of the box to help dissipate the ~94F heat the transformer will generate when I'm charging from a J1772.

You can see that it was custom built for me because it has my name on the label inside the wrapping!

Here's the test fit inside the box.

Here's the battery box back in place to show how it will look once installed.  What you can't see is I had to cut away some metal to allow the box to fit.  It was a curved piece of thin metal that was used to hold the spare tire in place.  No more spare tire, no more need for that bit of metal.

And here's how we access the charging sockets.  Both are waterproof in case some water gets in while I have the hood up during a charge.

I added some additional venting to the cover to make sure the heat isn't building up inside the box.

Here's the box, fully wired up inside.  Note the 3/8" hole drilled in the center of the transformer's potting material to allow me to run a big bolt through the box to hold it in place.  I also cut some steel spacers to size to center the transformer from side to side in the box to increase airflow.

You can't see it from here, but I installed the AVC1 board from Modular EV Power inside the box.  This board implements the car side of the J1772 safety charging protocol.  You could jury rig something up to fake it out, but for $37 on eBay you can't go wrong.  I hooked up 12VDC and ground, AC ground and a wire to the Proximity and Pilot pins of the J1772 socket.  I didn't take advantage of it yet, but it has normally-open and normally-closed relay outputs.  You could use this to light up an indicator that the car is charging or put an interlock so you can't drive the car while you're charging.  Not that anyone would every do that, of course!



If I had to do it again, I would use the newer AVC2 board, as it's enclosed in a nice box with better mounting tabs to protect the electronics.



I could have used twist-on wire nuts for the AC cabling, but I don't trust them enough to stay in place with all of the vibration this will be subject to.  I used Polaris connectors, which we use for high-current, thick-conductor bonding at my solar power company.  They're also dipped in plastic so they won't short out against anything else in the box.

Now that it was all wired up, it was time to test it.  I connected my Schneider station to a 240V breaker in my workshop.

This is the guts of the Schneider unit.  Technically it's not a "charger", it only delivers AC power to the charger mounted inside your car.  This is known in the industry as EVSE, Electric Vehicle Supply Equipment.  It consists of a couple of fuses, a contactor and a small circuit board that implements the EVSE side of the J1772 safety protocol.

I flipped on the breaker and the top green light lit up, signaling that it was receiving power and was anxiously awaiting an electric car to appear nearby.

The first test of my charging system was plugging in a 120V extension cord.  This tests whether the 120V hot, neutral and ground are wired correctly to the output cable, without involving the transformer.  Good news, it worked!  You can see the light in the extension cord and the voltmeter reading 119.8V at the output of the box.

The big test was now plugging the Schneider into my box.  For this to work, everything had to be wired right - the 240V from the socket to the transformer, the transformer to the 120V circuit, and the AVC1 board connected and properly talking to the Schneider safety circuit.  Happily, when I plugged in the J1772 and the thumb toggle clicked into place, the small LED lit up on the AVC1 board indicating it was ready for charging, then the contactor clunked in the Schneider, then the voltmeter showed 119.5V!  As soon as I pressed the thumb switch, the Schneider and AVC disconnected and power stopped flowing, just like it should, even with the plug firmly seated in the socket.

Declaring success, I will wait for Saturday to tidy the wiring inside the box, mount the box to the side of the battery box and install it back in the car.  Then I'll do the final wiring back up to the relay box and the rest of the conversion wiring harness.

J1772 Car Charging Station

I have a plan to install a 3-car-size shade structure and put another 3.3KW of solar power on top of it.  This will get me down from about $30/month to a $0 electric bill, even with the burden of charging the car.

In order to move into the future I leveraged my employee discount at REC Solar / AEE Solar and bought a Schneider Electric J1772-standard EVSE (Electric Vehicle Service Equipment).  It's technically not a charger, but a "smart" device that delivers power to the car and works with the in-car J1772 controller and charger to intelligently charge the car.

I'll mount the EVSE to a post on the carport.  I will also add it to my profile on PlugShare to offer J1772 in addition to a 120V outlet to anyone who needs a charge in my area.

A Leaf in the Wild

I was driving by the Rabobank in Atascadero and decided to check on the charging station there.  I was glad to see a Nissan Leaf hooked up and charging!  I left one of my project cards and wrote "Congrats on the Leaf!" on the back.

The station has a sign explaining that it was installed as a joint venture by Solar City, California Air Resources Board, Rabobank and Tesla.  The goal was to build a series of charging stations between San Francisco and Los Angles.

Here's a closeup of the sign and the Tesla-branded charger.  I believe the charger has been retrofitted from the 2009 model to the recently-introduced J1772 connector.
 

Charger Plug and Wiring

The EA kit comes with a nice weatherproof 120V socket with male pins, designed to take the female end of an extension cord.  The manual has a suggested through-the-bodywork installation process.  After all of the work I did with this car, there's no way I'm drilling a big hole through it.  I decided to mount a box inside the front trunk, giving easy access by popping the front trunk, plugging in, the laying the trunk lid down.  This also gives me the option of moving it in the future, or adding a J1772 plug when I add a 240V charger.

I got a 4"x4"x4" plastic box with a removable gasketed lid at Lowe's.  I found a place for it in the front left corner of the front trunk, next to the battery box.  I mounted it in place with two bolts and a rubber strip to cushion the box from the vibration.

I then drilled a hole in the lid, sized to the plug from the EA kit.

Here's the plug in place for a test fit.

I mounted the plug with some nice stainless steel pan-head allen key bolts and nylock nuts.  I ran the EA-supplied cable from the plug and out of the box through a cable gland.

Here it is in place.

Last step was to land the wires onto the terminal block.  The top three terminals run over to the charger.