Sunday, May 13, 2012

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.