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J-Plug 40A J-1772 nozzle getting too hot?

I have purchased several OpenEVSE stations over the years, but today I am referring to my first, Order #4254 06Aug2017 "Model P50A "Advanced" - 40A Charging Station Powered by OpenEVSE".

I use this one with a 2014 Toyota RAV4 EV, which can draw 40A.  I have the EVSE configured for 40A max (240v) on a 50A supply circuit, with a ~20' run from the EVSE to the breakers panel.

I normally plug in when I arrive home, the vehicle has a timer set such that it calculates when to begin charging so that the vehicle is fully charged when I am about to depart the next day.  So, I'm normally handling a "cold" nozzle.  Today, I had occasion to need to charge during the day, so I set the vehicle to "charge immediately" and plugged in.  I was starting from around a 50% SOC.  I unplugged at around 85% SOC because I needed to move the vehicle.  Immediately, I noticed that "hot electrical/hot plastic" smell we come to recognize.  I found my cheap Raytec IR thermometer and was able to obtain a momentary reading of 200°F !  To me, that is a hair-raising temperature for an electrical connector.  By the time I got my phone camera ready to document, the highest reading I could obtain on the J-Plug was 189°F (see pics).

I see no discoloration/corrosion or melted bits on either the J-Plug or the vehicle's inlet nozzle.

What is a normal temperature for the J-Plug that's been run about 1.5 hours in 50°F ambient?  Should I replace this J-Plug?

Pictures are both attached, and links below:'s_2014_blue/Inlet_Nozzle/IMG_2295.jpg's_2014_blue/Inlet_Nozzle/IMG_2298.jpg's_2014_blue/Inlet_Nozzle/IMG_2299.jpg's_2014_blue/Inlet_Nozzle/IMG_2300.jpg

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The contacts should not get very hot, The wire insulation for EV charging is rated to 105C or 221F. 

There are some posts about melting sockets in the Toyota RAV4 EV.

A good contact on this issue is Tony Williams at QC Charge. He is an expert in the RAV4 and coincidently his company manufactured the plug/cable on your station.

I am aware of those nozzle failures of Schneider and Blink charging stations from a decade ago.  Note that the failures were not of the charging inlet/socket, but of the nozzles containing the female/spring contacts.

I have ordered a replacement nozzle & cable from the the OpenEVSE store (order #9011), SAE J1772 Type 1 - EV Cable 25 (48A) and will replace the nozzle and associated cable.

I've replaced the nozzle and cable with new.  The crimp connection of one of the high-current leads' sockets to the twin 12ga wires had failed:


I'm disappointed to see this, as the use was light (nightly charging at home of one vehicle, generally five days/week).

There is evidence of corrosion to some of the screws in the nozzle.  I'm surprised non-corrosive fasteners (eg stainless steel) weren't used.  I'm near Seattle, everything is wet most of the year, it's not reasonable to expect a nozzle to only be used in a dry environment.


I'm glad I was able to detect this failure prior to damaging the inlet socket on the vehicle.


Oof. This is one reason why I like soldered connections.

Unless you are an expert, never solder high-current conductors.  Crimps can be QC'd, solder connections can't, and there are so many ways to solder large conductors and large cross-section wires incorrectly that chances are much higher of a soldered connection failure than a mechanical crimp failure.

I've probably soldered tens of thousands of connectors & joints, but I'd never solder, say, house wiring, even though that was the standard -- 100 years ago!  Mechanical connections for high-current joints are the standard not because it's cheaper but because it's more reliable.

It's just too easy to under-heat or over-heat a large conductor.  You don't want solder wicking up the wire, either, only into the connector, and that's difficult to control.

This is a failed crimp (I believe) but I'd never suggest it wouldn't have failed if it had been soldered.

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