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I have an OpenEVSE unit with the small LCD screen and an Olimex Gateway WiFi module, running on 8.2.2 and 5.1.2 WiFi firmware. It was on 5.1.5, but I downgraded to 5.1.2 in an attempt to cure the problem, which it did not.

This unit has been basically working in our carport with the Smart ForTwo 453 EQ for some months. I say 'basically' as there has always been a charge starting issue, but I believe that is a car issue and unrelated to this problem.

A few weeks ago, plugging the EVSE in to the car did not trigger the 'Connected' status and after 20 or 30 seconds, the car's port started flashing red, meaning a 'communication error'. I unplugged and plugged back in, locked and unlocked the car multiple times, but the problem remained.

Since a newer OpenEVSE unit (with large LCD) in the garage was in range, I tried plugging that one in and it immediately worked perfectly. A quick test with the carport EVSE again showed that was still a problem, whereas the garage EVSE repeatedly worked without error. Hmmm…

Thinking that the cable/plug was the problem, when I had time (day before yesterday), I swapped the cables and once done, I tested with the (actually brand new) cable from the garage EVSE, now wired in to the carport EVSE and it worked perfectly for a few minutes until I switched it all off as charging was not required, thinking "job done".

However, when trying to charge the car yesterday with the carport EVSE, there were the same failure symptoms and the car flashed red. So despite the successful test the day before after swapping cables, the problem has not been fixed.

In order to charge the car, I again ran the cable from the garage EVSE to the car which started charging perfectly. So…

Irrespective of cable and plug used, the garage EVSE works and the carport EVSE fails, which means the cable is not the issue and the problem must actually be with the small screen EVSE (with Olimex gateway) in the carport.

The EVSE itself reports no errors and says it has 24v for the pilot line, but I can find no logs that indicate just what is occurring. What I can see is that when these 'failure to connect' problems occur, the EVSE does not report the vehicle is connected. Almost as if the pilot line is disconnected and so no communication with the car, which can however tell the plug is inserted and hence the red flashing error.

Since the entire cable has been swapped, it cannot be any physical cable issue and since all the connections have been undone and remade when swapping the cables, that pretty much rules out any simple poor connection issues.

So that leads me to the conclusion that a hardware issue has developed in the EVSE. It cannot be the relay as there are no such errors logged and anyway, it's not getting that far. The EVSE is not seeing that the car is connected, the car doesn't like the lack of response and charging will not start. So no relay involved, which leaves the WiFi and main control modules, but which is at fault?

I have no knowledge of the interplay between these modules regarding managing the control line and behaving accordingly, so would really appreciate some assistance with tracking this down.