OpenEVSE - Open Source Charging Station

Chris has redesigned the OpenEVSE Plus DIY for vertical resistors, space for the PS load resistors and a input for a current coil to show charging amps.

Chris sent me a sample board so I built it up. All of the normal functions work well. I have not yet tried the current display but that is on my to do list. This is a soon to be available board but from my perspective it looks GREAT! Putting the resistors in a vertical position instead of horizontal allows a very small board.

GlennD said:

Chris used to ship them out with the button disabled. If you are near Anaheim I will be happy to reprogram it for you with modified firmware. The stock is in 5A steps from 10A to 80A. I use 2A steps from 10A to 50A. There is currently no cables sold over 50A since they had problems overheating.

Click to expand...

I'm not near the happiest place on earth. But thanks for the offer. I'll plug my FTDI into it and mess around with it. Worse comes to worse I swap for my spare board. I think if I can get it done I'll build a guide on Chris' new DIY guide page. Thanks

Thank you for building the first one Glenn and providing great feedback. I would not have been able to build and test one for a few more days.

GlennD said:

Chris has redesigned the OpenEVSE Plus DIY for vertical resistors, space for the PS load resistors and a input for a current coil to show charging amps.

Chris sent me a sample board so I built it up. All of the normal functions work well. I have not yet tried the current display but that is on my to do list. This is a soon to be available board but from my perspective it looks GREAT! Putting the resistors in a vertical position instead of horizontal allows a very small board.

Click to expand...

Well I have tried the current display. I have tried both the CR Magnitics recommended coil and one from a Chinese current meter. I changed the burdon resistor to a 200 ohm 10 turn pot. A 100 ohm pot would be a better choice.

With a resistive load a 47 ohm read correctly on the CR coil with my 15A heat gun. The Chinese coil worked with 16 ohms. Both tracked OK.

I used the Chinese coil to make up my 32A EVSE since it was smaller.

I charged my Leaf with a RMS clamp on meter connected. As expected the reading was slightly off since a car charger does not represent a true sine wave. I set the current as close as I was able to the clamp on. A 100 ohm pot would have been better and for the Chinese coil a 50 ohm one would have been best. The Greenlee meter compared almost exactly to a Fluke meter from work.

My EVSE is inside the garage but the J1772 is outside. If I install a simple toggle switch on the pilot wire between the openevse board and the J1772 wiring, I assume that would prevent someone from using my EVSE? I want a way to disable it without use of the breaker while I am traveling.

asimba2 said:

My EVSE is inside the garage but the J1772 is outside. If I install a simple toggle switch on the pilot wire between the openevse board and the J1772 wiring, I assume that would prevent someone from using my EVSE? I want a way to disable it without use of the breaker while I am traveling.

Click to expand...

Not sure if J1772 transmits the VIN. If so, that could be a very easy way to stop others from using it.
Otherwise, maybe some sort of remote/button, maybe on the inside of the garage?

asimba2 said:

My EVSE is inside the garage but the J1772 is outside. If I install a simple toggle switch on the pilot wire between the openevse board and the J1772 wiring, I assume that would prevent someone from using my EVSE? I want a way to disable it without use of the breaker while I am traveling.

Click to expand...

That is a good way to disable it. Go for it.

The EVSE is really dumb. All it does is generate the pilot and connect power in a safe way. In no way does it digitally communicate with the car. It is simple and dumb.

I figured that would work, thanks for confirming.

Since I have some Barbouri Version 4.21 boards on hand I decided to see how they handled the latest changes.

The relay 2 connection already goes to the same place that Chris uses for the GFCI test so it just needs a connector.

The latest mod is to use Nick Sayer's current display. This consists of a 100K half voltage bias circuit, A burdon resisror and a current coil. CR Magnitics CR8450-1000 is recommended. All the hard work is in software. I also put a 5.1V zener on the port to ground since I do not like unprotected ports leaving the board.

Nick specifies a calculated burdon resistor but I used a 100 ohm 10 turn pot. Real world values vary and a car charger presents a load that is not a true sine wave. In any event the actual value was within 10% of the calculated value but I like adjustment.

The current display is added to Lincomatics Rapi branch on github. Since I am not using any rapi functions it seems stable.

mctom987 said:

asimba2 said:

My EVSE is inside the garage but the J1772 is outside. If I install a simple toggle switch on the pilot wire between the openevse board and the J1772 wiring, I assume that would prevent someone from using my EVSE? I want a way to disable it without use of the breaker while I am traveling.

Click to expand...

Not sure if J1772 transmits the VIN. If so, that could be a very easy way to stop others from using it.
Otherwise, maybe some sort of remote/button, maybe on the inside of the garage?

Click to expand...

You could always sign up for PlugShare and publish your home station for public use. I'm planning on doing this as soon as I save up enough money for a new EVSE.

OpenEVSE Plus

The OpenEVSE Plus is available as a very small surface mount unit and as a small DIY board.
All versions comply with the J1772 specification.

The most basic is the unit as a stand alone unit like the JuiceBox Basic. In this configuration there is no display at all and you must let the car show that it is charging.

The next version is to have a RGB status LED. This is the minimum that I recommend. The status light is green in standby, yellow when connected, blue when charging, and red for an error condition. The LED can be directly connected like in Barbouri’s ver 4.21 board or as an I2C unit like Chris supplies.

The unit will support a 2X16 display. It can be monochrome or color. This gives a text readout of the status.

If you have a display then you might as well add a select/ menu button. This allows you to stop and start charging and set modes with the menu.

The next enhancement was Goldserve’s addition of a real time clock. It can be an Ebay separate board or it can be built into the display driver board. This shows the time of day while charging and lets you delay charging. In many areas it is much cheaper to charge late at night.

The latest changes are by Nick Sayer. He wrote code for testing the GFCI circuit on power up and he integrated a current display into the charging window.


I am going to step through the menu of a fully optioned system. There is no setting for the current display. It is automatic.
You get to the menu with a long press of the button. Short presses step through options ans a long press sets the option.

Setup service Level
This has 3 choices. You can force L1,L2, or leave in in Auto and let the board do its thing.

Setup Max Current.
This allows the current in the mode you are in to be set.

Setup Diode Check
Enable or disable the Diode Check. Leave it enabled.

Setup Vent Req’d Check.
This is a holdover from lead acid batteries. Leave it enabled.

Setup Ground Check.
In the USA leave in enabled to provide personal protection.

Setup GFI Self Test
This checks the GFCI circuit on power up. Leave it enabled

Setup Date and Time.
This allows for the real time clock to be set.

Setup Delay Timer
This has a sub menu to turn on the timer and set start and stop times.

Setup Restart
This restarts the EVSE like you had just plugged it in.

Setup Exit
This exits the menu while saving any changes. This is the usual way to exit.

All of the OpenEVSE code is released to the public. It may be found on github under lincomatic.
You compile it under Arduino using early versions. I use ver 0.0023 and 1.01.

You need an ISP programmer to program the board. UsbTinyISP and UsbASP are commonly used. Chris sells a version of UsbASP on his site with special cables or you can get it cheap on Ebay and make your own cables.

Thanks Glen for all the great images of your work. I'll be starting my OpenEVSE build this weekend and reviewing your examples has given me confidence and helped me plan what I think will be a very good layout.

I believe I found a bug with OpenEVSE. If I connect the J1772 handle *before* plugging in my OpenEVSE to 120V, it will default to the 240V pilot. The only cure is to unplug the car then unplug the EVSE, then plug in the EVSE again, then the car. If I disconnect just the J1772 handle and reconnect, I still get the 240V pilot setting.

Here is a screenshot of my LeafDD showing a 25 amp pilot (really set to 24, the onboard charger isn't exact), and the "1" designates 120V. My brusa charger is running here since it will kick on for a 16+ amp pilot on 120V and draw 4 amps on the input (and about an amp on output).

If it is plugged in it can not do its self check. In that case it uses its defaults. The normal programming is to use the 240V defaults. It can be set to use either defaults.

If it was L2 charging and you had a power failure it would resume when power is restored using the defaults. If you had it set to L1 defaults it would only charge at 12A.

You should only connect the car after plugging into power so the self checks run.

GlennD said:

You should only connect the car after plugging into power so the self checks run.

Click to expand...

Right, but what if there is a power failure and I'm plugged in to L1? :? 2013+ models will draw up to 30 amps on 120V! :shock: Could the code be modified so that once the new charge session starts and it detects 120V, bring the pilot down to the L1 setting?

I guess I'll have to set mine to a 12A default... of course I'll mind the plug in order, was tired and not thinking last night... then I heard my brusa fans kick on...

JeremyW said:

GlennD said:

You should only connect the car after plugging into power so the self checks run.

Click to expand...

Right, but what if there is a power failure and I'm plugged in to L1? :? 2013+ models will draw up to 30 amps on 120V! :shock: Could the code be modified so that once the new charge session starts and it detects 120V, bring the pilot down to the L1 setting?

I guess I'll have to set mine to a 12A default... of course I'll mind the plug in order, was tired and not thinking last night... then I heard my brusa fans kick on...

Click to expand...

Maybe a programmer type like you could come up with the mod but I am strictly a tech. When I was in school computers were main frames connected to Teletype machines.

In thinking about it I think setting the default to L1 would be a safer bet. It would slow down the charging rate but at least it would still charge. I think I will modify my archives.

I'm missing something that must be obvious to others.

Why not test and set the right line voltage and current every time that the OpenEVSE receives power?

Bob

It is not a good idea to cycle the relays to test voltage if a vehicle is plugged in. Its not so bad when using 2 relays as they go one at a time but if you use a single relay the on board charger will recieve power when not expecting to see it.

The defaults can set to either L1 or L2 current setting.

It appears that Chris is trying to blow out the ver 2 units in advance of the ver 3 units.

A couple of months ago the price was $115 now it is $65.

http://store.openevse.com/collections/frontpage/products/openevse-plus-v2" onclick="window.open(this.href);return false;