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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.

Yes, looks like the car detects the cable and expects a response from the EVSE which does not respond as it does not know the car is connected.

However, as I said, this is a new cable and plug I just installed (ok, swapped from another EVSE but never previously actually used) with no change to the problem, so cannot be those, nor the basic connections. So why is the EVSE not seeing the car being connected?

The pilot line is connected to the main control module which presumably performs the functions of dealing with the control line and switching the relay. Under what circumstances can that module not see that the car is connected?

I'll try with a different car today to see if it's any different.

I just tested the EVSE with a different car and basically the EVSE does not see when the car is connected. If the EVSE was disabled and then enabled, it then suddenly sees the car and charging starts. When the EVSE was then disabled, charging stopped and when the cable was unplugged, the EVSE remained showing the car was connected.

So it seems the EVSE is unable to see a vehicle is connected - until you can make it start charging and then it does seem to know a car is there, but it doesn't seem to see the connection over the pilot line.

How this affects the car then depends on the car, but the EVSE is currently unable to read the control line.

So looks to me like the main control module is not working as it should, but is that caused by hardware or software?

Or is there any other reason why it has now developed this problem with the control line?