JeremyW wrote:CHAdeMO doesn't support a "dynamic" charge from a charger at least in the 0.9 spec. The protocol dictates that the charger tell the vehicle how much maximum current it supports, but that value is not suppose to change during the charge session. You will probably need some small amount of storage to make it work, or charge very slowly using less than the MPPT of the panels you have to provide some reserve.
I was afraid of that. Any idea of what would happen if the current varied during the charge? I guess the car would detect it and just shut everything down. Correct?
Yes, if the vehicle saw that the actual current differed by the CANbus reported value, the car would shut it down. The assumption is the charger is not controllable.
The CANbus data stream is in 100ms intervals.
You could write a program that varied the maximum charger current, because that's the only way it will make sense to the car, up to the max amps reported to the car from the charger.
So, the initial exchange would be the car saying it wants to receive up to 125amps, then the charger would respond with a 1 amp max message.
When the contactors close, you need to be able to ramp up at rate not to exceed 20 amps per second. The LEAF may or may not be ok with 20 amps instantaneously, that's why I picked 1 amp. That will take experimenting.
You could control the DC output with shutters on the panels, but I f you can't get the CANbus message and the current flowing within 100ms, it might not work. I am speaking from experience here by the way
Perhaps you could have an alternate load (like a battery) with similar impedance that would get the current flowing, then switch over at exactly the right moment
Then open your shutter VERY slowly to add extra amps, and make your CAN message follow the actual amps as the maximum allowed by the charger. The slower, the better, until you hit max power of 20 amps. By the way, the 2011-2012 LEAF might not be able to do this, but newer ones should.
Honestly, I think you'll find that you need a way to manage the DC output to make this work, but who knows? You might also be ok with ON / OFF at whatever amps are available with a 1 up to 20 amps initial ramp CANbus message, then immediately adjust the max amps from 20 to whatever is actually flowing, and adjust every 100ms.
Why not do this the EASY, far cheaper and simple way? Solar with a battery and off-grid inverter, then plug in with a normal J1772.
You will have to actively regulate the J1772 pilot signal to match the actual output of the solar, and the relatively small battery will give you some buffer.
The only real design work is the load regulator. We can help you with that. The rest is commercially available parts.
Do you want to plug in, or be a science experiment?