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DIY EVSE build using OpenEVSE Controller flips every 0,5 sec- EV connected, Not connected, EV connected

Hi all. I’ḿ new to the openenergymonitor site :slight_smile:

I procured the OpenEVSE controller and built an EVSE using DIY components, build my EV charger for my BMW i3-2019. All went well, build done, put it in daily use for 2 weeks time, and then it stopped working.

I did “my best” in debuging, read the forum, and ended up whit no 12 volt for the relay to pull the AC relay for starting the charge of the Car.
Glyn was so kind to send me a new module, of the new type (5,5 ?) Thanks :+1:
(old are on the way back)

Module recived and after the rebuild, a wifi update, check of EV state , by resistor and diode. (connect/not connected/ charging) the OpenEVSE controler boot and run whit out any errors.
But connected to the car it “flips”/trickels between EV connected, Not connected, EV connected in loop very 0,5 sec.
The car goes in to connected mode and waiting for charge to start.
but charging never starts.
I procured a new type 2 cable whit socket on, and have replaced it, as the debug test with resistor and diode works.
New cable mounted, but it still “flips/trickels” not connected,Ev connected, not connected… in a constant loop.

Now i need Help, please. what can i check for faults ?

pictures of my OpenEVSE charger:





Skjold Petersen

Attached photos to post - Moderator

Welcome to the OEM forum, Skjold.

Will you please post your pictures here. If the place you linked to goes away at some time in the future, your problem and the solution will not be of any help to anyone.

I’m sorry I cannot help you with yor problem, but someone who knows should come along soon.


I’ve just seen the photos of your unit. Before I go any further I just need to point out that you have not purchased on OpenEVSE kit, you purchased an OpenEVSE controller and built an EVSE using DIY components. Please could you edit your post to clarify that you did no use the full OpenEVSE kit.

The relay you have used is not suitable for 32A and stripboard is not designed to carry 32A and the terminal blocks and wire links are too small for 32A. It’s possible to purchase a reconditioned 40A contactor (the same unit we use for official OpenEVSE kits) for £5.50.

Delivering 32A for 10+ hrs is a serious amount of power, careful consideration must be given to the choice of control equipment to avoid overheating and ensure safe operation.

I can’t knowingly help to debug an unsafe setup. Please come back when you have changed the contactor to a CE approved 40A unit.

The t9es1l14-18 relay you are using has an 18V coil, this is probably why it’s not working from a 12V supply and this is probably why the first controller we sent you malfunctioned. The controller has a 12V 200mA rating for the 12V relay output, see datasheet. I would recommend using a contactor with a 240V coil like the one I recommended above.

I would check the earth connection of the controller.

I understand the 32 A concern. In Denmark normal households only have 3 x 16 A phase in to the house.
My DIY setup are only for 1 x 16 A phase. It is meant to run 6-10 A as i plan for a off grid solar setup to deliver charging, but it is not ready for now.

I will procure a different relay and try.

Regarding earth connection. Are the ground on the board link to the earth connection ?
So i can measure earth connection from earth of the 16 A phase to earth to the board, to the car, and to ground on the board ?

Ah ok, fair enough.

The controller is earthed using one of two of the mounting holes, the controller should be connected via this earth connection to your main earth from your incoming cable and the earth from the EV charging cable. All earths should be connected together.

It you’re still having trouble, I would recommend measuring the voltage on the pilot wire, see the explanation of the voltage levels for the different states: Basics of SAE J1772 : Support

It may be a good idea to test using an EV Simulator instead of your car: EV Simulator (KIT) - Shop | OpenEnergyMonitor

Update, I got some time last weekend to investigate more on the problem.
I have grounded the upper and lover mounting holds to the right side (low volt side) direct to the earth on the incoming 230 supply, ground, and the charging cable, ground. (yellow wire)

While waiting for the 40A contactor (relay) and to support the 18 volt relay, I have mounted a “slave” 12 volt relay and a separate 18 volt power supply to “pull” the 18 volt relay, only to test out the DIY setup, as i dont what do damage any components on the controller.

Testing a charge, i still have the same connected, not connected flip stage.
So thinking the only communication the controller and the car do, is the pilot tone and wire in the EV charging cable.

So i tracked down a local brand new Type 2 EV charging cable, cut the remote male end of (the one that normal fit to the the fixed charger plug) and mounted the cable, to rule out if this can be the problem.

Now it works :smiley:
I dont have an oscilloscope only a multi meter.
I have tried to ohm the wire in the defect charge cable, but i can not get it to show high resistance, only 0 ohm.So it seams to work… not. :disappointed:

Another question: You mention that the 40 contractor have a 240 volt coil. can the 12 volt handle a 240 volt coil ? I dont understand that.

The openevse controller has a 240V coil output, see AC RELAY COIL on the main 6-pin connector: