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I just purchased and installed the AVC2.r controller along with a J1772 inlet in my car this past weekend. I have no problems using it at home with an Aerovironment Turbocord240; it all works great. The problem I’m having is using it at work, which was the real reason I installed it.

The problem is that the EVSEs at work are offering a maximum of 8A, so when my Elcon PFC2500 charger demands 12A the EVSE shuts off. I emailed PowerFlex (who manages the EVSEs) and they tell me that, by the J1772 spec, my car is supposed to perform the load management. So now it seems I've installed J1772 for nothing -- I can no longer charge at work! (I would have been better off leaving the 120VAC inlet on there and hoping for access to the one standard outlet in the garage.) And I don't know what will happen at other public charging stations. Has no one run into this before me? It seems like it could be implemented in the ACV2 controller. Now, my particular charger doesn’t currently have any way to throttle back, but if I had some kind of signal coming from the ACV2 then I might be able to figure something out.
 

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I've attached the J1772 specs sent to me by PowerFlex. The last sentence at the bottom of page 14 says it:

"The EV shall use the pulse width to control the on-board charger input/output."

So it seems like I'd need a modified AVC2 which controls different outputs depending on the input pulse width from the EVSE. But again, seems like someone should have run into this already...
 

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The control pilot is half of the purpose of a J1772 EVSE. GFCI protection is the other. It's designed to prevent exactly what you tried to do, which is plug in a higher powered charger into a low power circuit.

In theory it should be rather simple to put a current limited buck converter between your inlet and your Elcon. The Elcon would have no problem accepting DC input as it recitfies the AC to DC anyway. You'd rectify the AC to a high voltage bus, use PWM to chop it and smooth it with an inductor. Use a shunt to measure the input current and set the PWM to keep it down to allowed current from the J1772 control pilot.

You probably won't see a ton of public L2 J1772 EVSEs that'll cause you problems. Most allow upwards of 30A of input current.

ga2500ev
 

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That's an idea. I think what I really want though, is a smarter AVC2, call it "AVC3". I've already gotten a response back from Elcon and for $45 (plus shipping) they will re-program my charger to accept a 2-5vdc analog input to control 0-100% of the DC output. So now what I need is something to replace the AVC2.r which actually pays attention to the PWM signal from the EVSE and then drives a 2-5 analog signal in response to that, to control my charger. I think I could probably make something like that myself. It seems a shame to start from scratch though, when Modular EV Power is 90% there with the AVC2. (They also replied, and recognized the problem, but didn't exactly offer to build me a modified controller.) Has anyone built their own AVC2-equivalent?
 

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You probably won't see a ton of public L2 J1772 EVSEs that'll cause you problems. Most allow upwards of 30A of input current.

ga2500ev

My experience (see some other posts about that) is that it actually causes more problems here in the NL over time. The reason is simple: the main feed of the EVSE is most of the time 3*32A. When having two cars plugged in ,it (EVSE) has to divide the 32A between the two causing the first EV that was connected to throttle down when a second EV connects.
Having a 'dumb' charger with a unit like the AVC doesnt work then.
Even my CP equiped Brusa chargers dont follow the exact CP specs as it seems causing all sorts of disconnect problems when using an EVSE with two EV's at the same time.
My solution was to manual throttle down with a switch causing the Brusa to limit AC current to 10A but even then it sometimes disturbs the EVSE's.
Some 'smart' EVSE's seem to do some challenge-response thing so see if the EV connected actually follows the CP signal so an manual switch doesnt work.
I'm looking into building something myself with active CP following and providing/generate an according PWM or Voltage output or even CANbus message.
 

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That's an idea. I think what I really want though, is a smarter AVC2, call it "AVC3". I've already gotten a response back from Elcon and for $45 (plus shipping) they will re-program my charger to accept a 2-5vdc analog input to control 0-100% of the DC output. So now what I need is something to replace the AVC2.r which actually pays attention to the PWM signal from the EVSE and then drives a 2-5 analog signal in response to that, to control my charger. I think I could probably make something like that myself. It seems a shame to start from scratch though, when Modular EV Power is 90% there with the AVC2. (They also replied, and recognized the problem, but didn't exactly offer to build me a modified controller.) Has anyone built their own AVC2-equivalent?
Looks like a job for an Arduino in my eyes. It could track the incoming PWM pilot signal using an opamp integrator and monitor the output current using a sensor like this one from SparkFun:

https://www.sparkfun.com/products/11005

The Arduino already has an analog out function that'll produce a PWM signal for your 2-5V to drive the charger. It would be a rather simple event loop to monitor to control pilot average voltage and set the Elcon control voltage to produce the output current required to meet the specification.

A circuit to monitor the control pilot can be found in the OpenEV project, which uses an Arduino to create an EVSE. Take a look at the CP read circuit on this page for details:

https://openev.freshdesk.com/support/solutions/articles/6000052070-theory-of-operation

Hope this gives you some ideas for your control circuit. The Arduino could easily replace all of the functionality of the AVC2 with a couple of helper circuits and a bit of programming.

ga2500ev
 
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