My Openevse build...

I need to get together with Chris and get the new dual EVSE board and build a 70A/30A version based on mitch672 's parts list.

 

I don't think it's a dual EVSE board he's working on, it's a fully integrated version, with the advanced power supply integrated with the OpenEVSE on a single PCB. I am finishing up my 75A OpenEVSE now, there is plenty of room in the enclosure to add a 2nd lower power EVSE, but it's going to require its own OpenEVSE, display and relay.. I'm feeding it with a 100A breaker, so you will have to manually adjust each EVSE so it's not possible to draw over 80A in total. There is nothing automatic yet, and they don't talk to each other yet, but it's certainly possible by connecting them together with the I2C buss and custom software

 

Hi Jimbo, thought I'd show you my 75A OpenEVSE, the NEMA enclosure I used is gigantic (12" X 16"), I had to go big to get one that could accomadate the 75A SquareD contactor which is 4.5" in height. the first 13-14 pictures show the 75A version. The 14-50 is a temporary connection until I have time to run the PVC and 3AWG wire to the 100A breaker, not important untl the Tesla Model S arrives, really.

OpenEVSE pictures by mitch672 - Photobucket

 

I used an Arduiono I had, plus the OpenEVSE shield I had, which is my test setup for testing new releases of the OpenEVSE code, I'm waiting for Chris to release the new integrated OpenEVSE for the permanent install, this is temporary and works for now, but it's not ideal and occasionally flakes out, it's not really designed to be used in an actual live install, but it mostly works. Seems my bigger issue is voltage spikes from the giant contactor engaging...

 

add some capacitors maybe?

 

Ye, the question is: where

I have the LCD displays I2C clock and data lines on 18" of unshielded wire, probably need to use a piece of shielded wire on that and ground the shield. I already had to ground the giant aluminum plate the LCD display and select switch are mounted to, as it was picking up static electricity and causing havoc with the Arduino.. This will probably wait until I get the actual OpenEVSE board to get done, I'm using it to charge the PiP and don't want to take it apart more than needed.

 

Jimbo, that threads pretty old, and it was a conceptual idea that could be done, but I don't think anyone has written any code to support the current sharing concept with multiple OpenEVSE boards - yet. Just an FYI, more work needs to be done, even when the hardware is available. I'd be thrilled to try it, I have the space to make my 75A OpenEVSE a dual unit, and it will be fed with a 100A breaker, so it could be tried.. when the code exists, for now you would need to manually set each one so the total doesn't exceed %80 of the total amperage available.

 

A multi-plug, amperage sharing, EVSE needs to become available for the home garage with multiple EVs but more importabtly to bring an affordable solution to workplace charging. Having a mix of plug-ins at the workplace able to intelligently share a single 200A supply/meter will accelerate the availability of workplace charging. Just imagine a row of 20 parking spaces, each with J1772 plugs and everyone getting their max charge rates off of one 200A panel.

One or two of them might be designated for 75A service, the bulk at 30A, and a few current monitored 50A RV outlets for Teslas.

 

You will need a varistor directly across the contactor coil. That will absorb the energy built up in the coil when the microcontroller drops the coil.

 

Thanks, any idea of the value or a DigiKey part # (even better)

 

What is the coil voltage? You should be able to pick out the correct device from this link.

http://www.mouser.com/catalog/catalogusd/645/693.pdf

 

The contactor coil runs on 240V line voltage...
I found both 250VAC and 275VAC at DigiKey, they don't clamp until 429V...
V250LT20AP Littelfuse Inc | F5598CT-ND | DigiKey

 

Great thread..

I have some students looking at multi EVSe as a project (first we have to get campus on board), because the real cost for install with will be running the new power service -- and we want to maximize the number of cars we can handel, even if they get down to only 2Kwh each.. We looked at the old thread and are going back and forth between this type of design and a bluetooth communication channel between independent openEVSEs. We want to look at bluetooth for other reasons (to allow mananging who is charging etc). Love to hear more from those who have already build them what is their view.. a stack or independent uints that talk to each other?

 

Get ahead of the curve and go with powerline communications, P1901. IEEE 1901 - Wikipedia, the free encyclopedia

You can add an off the shelf homeplug<->wifi bridge for your wireless connectivity to smartphones as well as bridge to an intra/internet connection.

I found that chargepoint has published their networking protocol as well, so using their network to check EVSE status would be a bonus if openEVSE talked chargepoint.

I am starting to lean toward standalone openEVSEs on a shared circuit talking to each other and to a TED 5000 monitoring the total load on the circuit. If the individual openEVSEs could log to the TED through the PLC protocol, that would be a plus.

Be sure to include provisions for monitoring a couple of raw RV outlets (Tesla) on the circuit, another way to leverage the TED 5000 perhaps.

I might have a sponsor for your class project. Austin Energy is thinking about adding a charging solution for the long term parking lot at the airport, maybe shared with the adjacent employee parking lot.

 

Can I get you out to our Ski Club to wire some baseboard heaters? Nice work!

 

What problem is the electrical noise causing? If it is hang up or reset of the microcontorller, you might try making the 1 mFd +5V supply capacitor as close to the micr as possible. ANd terminate unused microcontroller I/O. Or at least make sure they are set to outputs in the start routine. You can also contorl register watchdog routines in the program loop.