Weekend(s) Project - DIY EVSE

[chris1howell]

The pictures are here... http://www.mynissanleaf.com/viewtopic.php?f=26&t=2633&start=0

They are quite helpful. I am looking for the dimensions of the main board, the mounting locations and the position of the LED's. I have a rough idea because I know the size of the relays and I can use those as a reference point.

My plan is to remove the main board and transformer and replace it with my board and use it as a development platform to keep moving forward. After seeing the insides of the other EVSE's I know there is a lot of room to build a much better EVSE.

 

[chris1howell]

The prototype boards arrived Friday and a spent another weekend working...

Board 1 has all the high voltage parts on it, including the relays, terminal blocks and connecting wires. The microprocessor is and supporting components installed and the Firmware boot loader has been installed and verified. Next up for this board is adding the USB chip and components and loading the EVSE software.

Board 2 will be used for testing the ground fault circuit.

Board 3 will be used for testing the power supply.


PCB by chris1howell, on Flickr



PCB empty by chris1howell, on Flickr

 

[fotajoye]

The PCB looks good and well planned; cannot wait to see how it intergrates with the other boards.

 

[chris1howell]

Thanks fotajoya...

I am really happy with how the boards turned out. I have found that I had made a few mistakes so far. The silk screen outline for the Power supply and relays are on the bottom of the board, I forgot to label a few things and the holes for the power supply are just a tiny bit too small...

I am having a good time with all the hardware lately, one of these days I will have to work on the software again... This quick little weekend experiment has really taken a life of its own, but I am having a lot of fun...

 

[nader]

Subscribing.

I would definitely pay for a compact EVSE that can charge at 16 amps.

I am already buying the 20 amp version of the Quick220 so being able to take advantage of the extra amps is welcomed!

Nader

 

[fotajoye]

Chris:
Been following your progress and interested in knowing if you intend to offer the fruits of your labor to your fellow members of the forum. A kit would be the way to go for me.

 

[chris1howell]

fotajoye,

I am planning to offer something... I just do not know exactly what yet.

I am considering:
Full EVSE modules

Modules that have all the low voltage components the control pilot, GFI and microprocessor components with outputs for external relays.

Kits... however in the current design most of the components are very small surface mount so it may not be practical unless I increase the size overall size to allow use of common size components.

If I decide to do none of the above, I plan to release the hardware board files and schematics and software as Open Source.


I am making good progress on the testing... I now have the Firmware and improved software loaded, USB working for both software updating and monitoring. I have tested the current sensor and have added the kWh meter. I am about ready to test the GFI fault/reset logic and next up after that is the actual GFI detection circuit.

I also have a second design just about finished which is really tiny... It gets rid of the "diode check" and all the extra parts required (most EVSE's do not implement this anyway). It also does not have the high voltage parts such as the relays on board. ---more to come soon---

Before I release anything, I need to finish testing and I would also like to have a qualified Electrical Engineer or two look over the design and hardware. I know there are a couple around this board.

 

[fotajoye]

Chris:
My forte is software and I'm not up to date on circuits anymore; however, if I may I offer the following: As you know, electronics move to ever smaller form factors; I suggest a product that's about the size of the Nissan brick, that plugs into a twist lock 240v a/c receptacle, capable of the full 16 amp current service. But, design it for a possible update to over 32 amps because few doubt that the next generation of the Leaf will have the larger charger; as will other car makers. Also, make it portable and also, as an option, a fixed unit by providing a fixture plate and strain relief that will fit the final product. I would consider selling it as a separate unit and leave the Nissan brick as is; an emergency device. Your device, if priced right, can service as a mounted unit for those who want a full level 2 EVSE for home and/or for portable use when on trips.

Sounds as if you are making good progress on the prototype and as you know leaving the ego at home and having a couple of other EEs test and assist in proving the product is a sound approach.

Additionally, you may want to offer a kit with a pre-built and tested logic unit and make the large stuff the kit. Lots of ways to go here; however, I think the key is to undercut the competition.

 

[chris1howell]

This past weekend was a really good weekend, as far a progress goes. On Saturday, I had the pleasure of meeting a handful of leafers at the SoCal gathering and my wife had the opportunity to see a Leaf in person and go for a ride... We discussed the current state of EVSE offerings and modifications. I was also able to demonstrate some of the features and progress of my weekend(s) project.

The three EVSE's are at various stages of completion for targeted testing. The GFI fault/reset logic has been successfully completed both in hardware and software.

I am currently working on the power supply testing, Ground fault detection and source code cleanup.

photo2 by chris1howell, on Flickr

Oops, I found a mistake...

photo4 by chris1howell, on Flickr

 

[fotajoye]

Chris:
You are having way too much fun; thanks for keeping us updated; I'm still using the Nissan brick to charge and waiting to see what you come up with.



Black SV #669

 

[chris1howell]

I am having a lot of fun. I need something to do while I wait for my Leaf...

 

[garygid]

I guess you cannot play with that darling baby all the time.
Her nickname might be "Hopper" or some such?

 

[chris1howell]

True, she does have to sleep eventually... "Hopper" is a good one she does love to bounce. She is sleeping through the night now so I can’t lovingly call her "Sleep Slayer" anymore.

On topic… I successfully tested the GFI detection last night. I passed current through the CT coil slightly over the trip threshold. The circuit tripped and microprocessor detected the trip as expected and started a 5 second count down timer to reset the GFI hardware. In the next couple days, I am planning to test current under the threshold to see how tolerant the circuit is to nuisance trips…

 

[garygid]

Chris,
Good work.
I think "normal" GFI trip is about 5 ma,
but the in-EVSE trip is more like 20 ma.
I would make firmware options for 5, 7.5, 10, 15, and 20 ma.
See your PM.

 

[Ingineer]

Thanks fotajoya...

I am really happy with how the boards turned out. I have found that I had made a few mistakes so far. The silk screen outline for the Power supply and relays are on the bottom of the board, I forgot to label a few things and the holes for the power supply are just a tiny bit too small...

I am having a good time with all the hardware lately, one of these days I will have to work on the software again... This quick little weekend experiment has really taken a life of its own, but I am having a lot of fun...

Nice Job Chris!

I have ideas for a "boxless" design with a split architecture, where there some of the circuitry is in the AC plug housing, and the rest is in the J-Plug. Unfortunately due to liability and the cost of UL listing, I doubt I'll ever do anything.

What core are you using?

-Phil

 

[fotajoye]

Forgive me for jumping in; just some thoughts from an old retired guy. Don't EEs have insurance for "errors and obmissions" like CEs? Or, maybe if you decide to offer a kit, perhaps a brief contract with the buyer declining libility would be enough, especially if you used UL/CE parts,etc. Something to look into. I would hate to see all this good EE work completed and not offered, only to fall into the Lawyer's Black Hole of the libility (who to blame) game.

If you decide not to build a product, please offer you work as open source to the members. If you look at what Megasquirt does for auto FI control systems, you will get the idea. They've been around for years and finally have some mature kit products to offer. May be they could be of value to you. And, their products cover a wide spectrum of installations that yours don't.

Anyway, both of you guys are doing the members here a great service in solving the problems behind the SAE J1772 builds.

 

[chris1howell]

Phil I sent you a PM....

 

[fotajoye]

Chris:
How's the project going you haven't posted for awhile and I'm hoping things are good.

 

[chris1howell]

Fotajoye...
Things are good. I have been testing all the basic functions of the EVSE, so far no major issues. I have also spent some time working on the code again. I have another set of three Printed Circuit Boards with some minor changes on the way. The new boards are more universal, I have taken the power supply and relays off the main board. This makes it easier to test and smaller (they are also a lot less expensive). I have provided the schematics and source code to a couple members on this board, I will be giving them each a board to test as soon as they arrive and I get them built...

I am also working on a smaller version and an enhanced version...

I will try to put up a video of the current progress this weekend...

More to come...

Chris

 

[fotajoye]

Chris:
Excellent! I think you have a good thing going for yourself and the members. My old Cal teacher would be pleased; always said "The better engineers do the best worse-case analysis and empirical data gathering(testing)."