Here's a brief how-to for the thermal protection modification on the Rav4 EV, though this should generally apply to any EV with some modifications. I don't think it's needed on the 2011-2012 Leaf, as the most current the inlet will ever see is well below 20 amps. But on other EV's, and possibly the upcoming 2013 Leaf, this can be cheap insurance. The Inlet on the Leaf is over $400, and much more on some other EV's! In addition, it's conceivable that a thermal fault at the J1772 connection could lead to a fire.
DANGER! WARNING! CAUTION! DO NOT attempt this modification unless you are a fully qualified engineer with years of experience! It will most definitely void your warranty, could damage your car, cause the end of the world, kill off the dinosaurs, etc.
Here's the parts list: (Links to Digikey)
1 thermostat - 158 degree
1 resistor - 330 ohm 1 or 2 watt - 5%
1 roll 3M orange electrical tape
3 inches (min) 1/4" Heat Shrink with Adhesive
If you are performing this mod on another car, you may wish to get 2 thermostats and wire them in series, and some adhesive-lined heat shrink to encase them, each with one AC wire to the tab. After some testing with hot parts, I found a more elegant way, at least on the Rav4, we can implement this with only 1 thermostat.
Be VERY CAREFUL not to scratch the paint on the car! I recommend you tape some cardboard around the area with liberal use of masking tape to protect the finish. (Ask me how I know!)
1. Remove the four 10mm bolts from the Inlet, and the two shown here in the wheel well:
2. Unsnap the 2 connectors and the 4 black ziptie cable clamps from the orange plastic. I found this easiest with a butterknife pushed under the little base.
3. Carefully remove all this orange tape from the cabling and the orange plastic wire loom about 4 inches down. Unsnap the orange contact retention basket from the back of the inlet. There are 3 tangs that must be released, which I used a small flat-blade on.
4. Note where all the wires go, then remove the retention basket from them. Drill 2 tiny holes (not much larger than the wire used on the thermostat) in the TOP of the basket. Be VERY CAREFUL not to damage the basket or the pins. Another method (maybe for another EV) would be to use 2 thermostats heatshrink a thermostat to each of the AC wires, tab against the wire, as close to the back of the inlet as possible. (AC wires are usually the 2 heavy Orange ones)
5. Slide the thermostat into the BACK of the inlet as shown, making sure the tab side is toward the center of the inlet. It won't go in as far if you have it upside down. Put the wires back into the basket and feed the 2 thermostat wires into the small holes you drilled. Re-attach the basket, taking care not to pinch the thermostat wires. It takes 5 hands.
6. Cut the 2 small red wires leaving enough to splice. This is the proximity line. It's the wire(s) connected to the small pin on the lower right if viewing the front of the inlet. Slide a piece of 1/4" heat shrink down over the red wires. Be sure to use enough to fully cover the resistor and splices. Insert the 330 ohm resistor and connect the thermostat across it as shown. If you are using 2 thermostats for another EV, then connect them in series, then across the resistor. Be sure all the wires are well wrapped and then solder all the connections.
7. Now, I decided I should test the setup. (You can skip this test if you want) I unsnapped the basket again and then connected a multimeter (set to ohms) across the resistor and used my heat gun on low to heat the thermostat until it opened and then a little longer. I then quickly re-assembled the basket and temporarily connected an EVSE to the inlet. After waiting for what seemed forever, the thermostat finally cooled off and it started charging. SUCCESS! I then disconnected everything and slid the heatshrink over the resistor and it's soldered connections. Use a heat gun or other heat source (be careful!) to fully shrink the heat-shrink and melt it's adhesive sealant payload. Should look something like like the picture below. Now, if you didn't perform the first test, temporarily connect an EVSE to the inlet and verify it's charging properly.
8. Thoroughly re-tape the wiring and orange plastic wire loom. Use the orange 3M tape. (Don't use black like I did)
9. Re-assemble everything, clean all the mess up. Pat yourself on the back with one of those 5 hands! :lol:
You can sleep soundly knowing your EV will never have an overheated inlet problem. If the temperature gets too high, it will simply suspend charging until it's cool. If you ever notice charging taking longer than usual, feel for excessive heat or check it with an IR thermometer.
-Phil