Open EVSE

[Don]

Chris Howell has been working on an open source code EVSE for a couple years now. Each revision of it he develops is a more refined, more professional, easier to build and use product than the last one. You can read the history of it at this thread on the Leaf forum

http://www.mynissanleaf.com/viewtopic.php?f=26&t=6546

It's nearly 50 pages of posts, but if the topic intrests you at all, the history of how it all came to be is pretty interesting . . . . or at least it was to me

Chris maintains a website with all the latest information, revisions, downloads, links to sources for parts and all here

http://code.google.com/p/open-evse/

I decided to build me one and began collecting the parts about 3 months ago. I posted here about my charge handle with the built in LED light http://myimiev.com/forum/viewtopic.php?f=7&t=425&hilit=LED&start=10

Since these are mostly 'home made' they come in all shapes and sizes - You can build them with or without the LCD readout and you can make them fixed or portable, depending on what type of enclosure you build it in. I chose a small Pelican case for mine, because it's easy to open and I wanted to mount it on a wall. Many others use smaller, more rugged enclosures and use them as portable units. My portable unit is my EVSE Upgraded OEM Mitsu Panasonic unit which charges at 12 amps on both 120 and 240 volts

Here's the completed unit in the case

A view with the door open

Back view showing more of the components

Plugged in, ready to charge - The blue ring is the illuminated switch which selects charge current, etc

Charging the car

This unit is using the latest release firmware which gives you adjustable charge current. On L1 it will charge at 6, 8, 10, 12, 14, 15, or 16 amps. On L2 it can be adjusted to 6, 8, 10, 12, 14, 16 or 20 amps. Mine is using 20 amp fuses, so it probably won't do 20 amps without changing those - The iMiEV doesn't need 16 or 20 amps anyway

It also has Auto Detect of L1/L2, GFCI protection, a ground check, a diode check, a vent required check, and stuck relay protection - It's actually much more J1772 compliant than the factory EVSE

Depending on what parts you buy and where you source them, it's about a $350 project, give or take. I didn't want a long pigtail, so rather than spend a fortune on one and end up cutting it in half, I bought 10 feet of 7 conductor 16 gauge wire and used two strands for each charge conductor. That left one for ground, one for the pilot signal and I used the 7th one to power my charge handle LED from the unit's 5 VDC supply

Don

 

[MLucas]

I saw this and really wanted to build it. If I had more time, I would have definitely gone this route instead of buying the $800 dollar Square D Level 2 EVSE. I think the total price is about $650, so we still save a lot going this route and the builder gets to customize it the way they like.

I noted Chris had stopped accepting orders for the kit at the time I decided to buy the car to catch up on backorders. Between buying the car and having to drive it to work in a week, I just couldn't come up with the time to make this happen.

On a side note, at the low volume pricing of $650 you can see how we are getting ripped off buying the off the shelf EVSEs. With those companies buying power, the parts for them have to cost even less. The Square D is about as basic as you can get, a box, a PCB to sense the +9V pilot signal + GFCI, a big fuse and a relay. That is all that is inside of them things. The Square D doesn't even come with any monitoring capability like this one does.

 

[Don]

My build was less than $400 and if you opted not to have the display, it could be done for even less than that

Don

 

[MLucas]

My build was less than $400 and if you opted not to have the display, it could be done for even less than that.

What a deal! I forgot about opting out of the display, right - you don't really need that at all if you plan to monitor this from your computer or smartphone.

 

[evcar]

Chris told me I'm on waiting list - I have placed order about week ago...?
As I'm in Poland I like to have one - and I will try to build more by my friend-electrician....
Really excited to have it

 

[Don]

What a deal! I forgot about opting out of the display, right - you don't really need that at all if you plan to monitor this from your computer or smartphone

It has no provisions for monitoring with a smartphone or anything else. Without the display, it's much like the OEM EVSE after it's been upgraded by EVSE Upgrade.com - A fixed charge current for L1 and L2 and automatic switching between the two. The display and the front panel switch on mine allows the user to select whatever charge current they want for L1 and they can select a different charge current for L2. The unit automatically switches between L1 and L2 when you plug it into either 120 or 240 volts

Commercially made EVSE's must meet all sorts of codes and homebuilt units don't meet any of those, so it's natural I suppose that the cost is higher for the commercially produced units

It's really nice that Chris and the others at Open EVSE provide all the information that they do in the public domain for those of us who would like to do our own thing - I don't know of any other way you could get a unit as versatile as this one except to build it yourself - It's a rewarding project, but probably not something for those who have no electronics background at all and/or those who have never used a soldering iron to build anything. It's not an especially difficult job for someone with the appropriate background, but it's not something everyone could do

Don

 

[MLucas]

You are right again, Don. I was thinking of the Open Home Energy Monitor project. But, I'm sure with a little bit of ingenuity and few more parts this can be made to be read by a remote server serving up a web page which then would be accessible by any web enabled device.

I've been looking at the arduino projects and going to delve more into this field. I've read over on the Leaf forum Lincomatic has built an SOC gauge for the ODB port. They've figured out the wiring and the codes, looks really nice and gives more information than our instruments give us.

http://blog.lincomatic.com/?p=639

 

[Don]

Yes, they're headed into projects that can be monitored/controlled using cel phones and iPads and it won't be long before you can build something along those lines in your personal workshop . . . . or at the kitchen table in my case Pretty soon they'll have an EVSE that looks like a laptop power supply and is controlled by your laptop as well - Start, stop at any time and charge using whatever amp or kwh rate you like, with the results showing up in a spreadsheet

BTW - Lincomatic wrote much of the code that the version I built runs on. As I understand it, he's a real programming wizard and Chris is an expert at redesigning circuit boards and shrinking them to their minimum size - A great combination

There are so many more Leaf owners than we have at this point - Hopefully we'll one day have some talented engineers playing around with the software/hardware this car runs on and we'll have lots more options to make modifications and improvements

Don

 

[PV1]

Quick question, the OP says that the open EVSE can handle 16 amps at 120 VAC. Will the i charge at 16 amps at level 1, and if not, what is the max amperage (or wattage) of the onboard charger at 120 VAC?

 

[Don]

I looked high and low for some spec on what the car's charger is rated for L1 charging - Couldn't find a thing

I set my Open EVSE for L1, 16 amps, plugged it into my wattmeter and began charging the car. The wattmeter reads 1725 watts, 14.6 amps @ 118 volts. Don't know for sure, but I would guess this is the designed maximum for the charger when used on L1

Hope this helps,

Don

 

[PV1]

Thanks. Also, for those using a Kill a Watt, the Max rating on those is 15 amps. Above this, they'll either not read current correctly or get cooked. My meter just shuts off when I used my heater with it, which pulls 1,400 watts.

Are open EVSE's easy to build? Also, any idea for a near full recharge time at full power level 1? What can be soaked up in 8 hours after a 50 mile drive?

 

[Don]

Thanks. Also, for those using a Kill a Watt, the Max rating on those is 15 amps. Above this, they'll either not read current correctly or get cooked. My meter just shuts off when I used my heater with it, which pulls 1,400 watts

1400 watts is only 11.7 amps - Your meter should have handled that easily. Mine is not a Kill-a-Watt, but it too is rated at 15 amps (1800 watts) and it works fine with the EVSE

Are open EVSE's easy to build? Also, any idea for a near full recharge time at full power level 1? What can be soaked up in 8 hours after a 50 mile drive?

Well, Mitsu says 22 hours for a full recharge using the 960 watt EVSE they supply, so 1725 watts should get the same job done in about 12 hours

Building an EVSE is about as difficult as most other electronic projects - If you've never done anything like this before and you're you don't have good soldering skills, it's probably not the project you'd want to learn on, but if you have someone qualified looking over your shoulder, keeping you on the right track, it's not that hard. The display portion actually *is* a $25 DIY kit - You can give that a go and if it all turns out well, you're probably not going to have any problems with the rest of it - Chris sells the main board complete, so assembling and wiring it up isn't that difficult a job, once the display is completed

On the other hand, you can build it without the display . . . . the board has a tri-color LED on it which tells you the state of the EVSE. Green = Ready, Blue = Charging, Red = Fault, much like the Panasonic EVSE that comes with the car. You could build a portable version without the display in a very small box . . . . everything would fit into a standard outlet box, much smaller than the OEM EVSE - But you do need the display if you want to be able to be able to select different charging currents

You could also have the OEM charger upgraded - That will give you 12 amps at both L1 and L2 and it's very rugged and portable . . . . ideal for a charger to carry with you and use away from home. That's the way I went. My Open EVSE is mounted on the wall of the garage and the OEM one is mainly for back-up or travel

Don

 

[PV1]

Thanks. At work, I now have 20 amp 120 VAC outlets available, on their own circuit with nothing else. I have 8 hours the car will be sitting, so I was just seeing what can be soaked up in that timeframe. I have a 50 mile drive, 19 on the highway (65 MPH), the rest on main roads at 55 or below, with minimal HVAC. If I'm in a pinch, there's a Mitsubishi dealer close by that I can charge at after work before heading home.

It's a construction site temporary power pole that my work owns, so I can probably get a 220 plug put in without much hassle. We've already added them to three others.

I like that pelican case. What is it about transparent electronics that is so cool? I'll probably go with the screen because I need to be able to select charge rates, and I like to see what the thing's thinking.

 

[PV1]

Is it possible for you to post a parts list? Also, I've been looking at the open EVSE site, what is the LCD listed as? What all is involved with putting it together? The rest of the EVSE seems simple.

I've modified a power supply to add Bluetooth capabilities to my Roomba, so I'm fimiliar with soldering, not to mention my custom NiMH battery pack for my off grid PV system. It wasn't circuit board soldering, but wire-to-wire, which was more difficult.

http://home.earthlink.net/~timster
http://www.robotreviews.com/chat/viewtopic.php?f=4&t=16215&p=109232

 

[Don]

All of the parts info and build instructions are listed there on the Open EVSE site, though you do have to dig around a bit to find everything - It's not terribly well organized

This is the dispay that most people are using, though there are others which will work

http://www.adafruit.com/products/714

The advantage to the RGB display is that it changes color depending on the state of the EVSE, just as the tri-color LED on the board does

There are also a couple different versions of the EVSE main board available. Mine is one that isn't shown on the website . . . . I'm not certain Chris is building and selling any more of the one I got. It's based on a 5 volt power supply and it has a pair of 5 volt relays for the main contactors mounted directly on the board. This makes it the easiest version to wire up . . . . fewest connections since the relays are already on the board. I guess the only downside is with those relays it's limited to 20 amps, 120/240, but that's plenty if you're just building it for an iMiEV. Others are building this EVSE using relays up to 75 amps for use with the Tesla Model S with dual 10Kw chargers. Most using the 12 volt version of the board use a dual 30 amp 12 volt relay http://www.digikey.com/product-detail/en/T92P7D22-12/PB486-ND/365921?cur=USD

Chris is pretty good at answering e-mails, so when you think you know what you want, get with him to put your name on the list - There's usually a waiting period of 4 - 6 weeks to get a board . . . . he's building them as fast as he can

Don

 

[PV1]

Thanks. I've been digging some more, I guess the arduino shield is the display. My EVSE will probably only see an I and a Volt. My Dad's looking at a Volt, and it'll get a level 2 Voltec EVSE if he buys it. This will be an 'out and about' EVSE, for destination and opportunity charging. The plans I'm going to follow uses a 30 amp relay, which'll be plenty. I'm not building a Tesla Supercharger, :mrgreen: .

I found the tutorial for the display assembly, seems easy. Also, how does the EVSE handle a GFCI outlet?

 

[Wee John]

Is it possible for you to post a parts list? Also, I've been looking at the open EVSE site, what is the LCD listed as?

http://code.google.com/p/open-evse/wiki/OpenEVSEv1partslist

http://code.google.com/p/open-evse/wiki/OpenEVSEv2partslist

http://code.google.com/p/open-evse/wiki/OpenEVSEv4partslist

I got my display in last week-thanks Don. I also got the Leviton cable http://code.google.com/p/open-evse/wiki/J1772CableSources and got on the waiting list for the tested board and the advanced power supply http://code.google.com/p/open-evse/wiki/Ordering. I haven't had time to play yet.

 

[Don]

I found the tutorial for the display assembly, seems easy. Also, how does the EVSE handle a GFCI outlet?

It doesn't - Since the EVSE has built-in GFCI, it trips a standard GFCI outlet. This kinda through me for a loop when I first built it and was testing it on 120 volts in our kitchen . . . . once I moved it to an ordinary outlet, it worked just fine :lol:

Since my upgraded OEM EVSE came with an L6-20P twistlock pigtail on it, when I wired up my garage, I used a twistlock for my 240 volt socket, so when I went to build my Open EVSE I bought a cord with a molded L6-20P connector on it so it would plug into the same socket - Cut off the unneeded C19 socket and wire the cord directly into your EVSE

http://www.ebay.com/itm/Heavy-Duty-C19-to-L6-20P-10-ft-12AWG-Heavy-Duty-Power-Cord-250V-20A-/330776923653?pt=US_Power_Cables_Connectors&hash=item4d03d74e05

I like the twist locks because my outlet is mounted in the garage ceiling and the cord stays put in the socket. I also bought the optional pigtail from EVSE Upgrade for converting the twistlock to a standard NEMA 5-15P so using that either EVSE can be quickly plugged into a standard household outlet for L1 use. I have a standard NEMA 5-15 120 volt household socket right next to the 240 twistlock socket in my garage, so I can use either L1 or L2 when desired for recharging. Like the EVSE Upgrade, the OPEN EVSE is automatic switching, so it sets itself to either L1 or L2 depending on what you plug it into. With this arrangement, it's a snap to use it either way. EVSE Upgrade also sells a twistlock pigtail with nothing on the other end which you can use to plug into any dryer outlet or other 240 volt source . . . . just buy whatever plug you need and install it on the pigtail. The L6-20P cord makes all sorts of conversions quick and easy to do, so it's ideal for something you might want to plug into all sorts of outlets

If you were going to mount a 240 volt outlet on the pole outside your work (or at your house) the twistlock would be a good choice because it would keep anyone else from plugging into it . . . . most folks have no idea what a twistlock is for, or whether it's 120 or 240 volts. It can be used for either

Don

 

[PV1]

I'll need to do something about that. The 110 volt plug on the pole is GFCI, as is the dedicated in our garage. Does the stock Mitsubishi EVSE trip GFCI's? If it does, I'll definitely have to install 220 on the pole and a non-GFCI in our garage.

 

[Don]

The OEM EVSE works fine with GFCI - They recommend you use a protected outlet

Chris says it's possible to disable the GFCI on the Open EVSE - Think you'll need to add a switch to the front panel for that and you'll also need to turn off the ground check and the stuck relay check in the menu and it should work fine

When you buy the car, sending your OEM EVSE off to EVSE Upgrade would probably be a good investment for you - You'd then have a very rugged 120/240 12 amp portable unit for use away from home

Don